Flame Test Concept Inventory

MIAMI UNIVERSITY The Graduate School

Certificate for Approving the Dissertation

We hereby approve the Dissertation of

Ana V. Mayo

Candidate for the Degree:

Doctor of Philosophy

Director Dr. Stacey Lowery Bretz

Committee Chair Dr. Ellen J. Yezierski

Reader Dr. Neil D. Danielson

Reader Dr. Richard T. Taylor

Graduate School Representative Dr. Jennifer Blue ABSTRACT

ATOMIC EMISSION MISCONCEPTIONS AS INVESTIGATED THROUGH STUDENT INTERVIEWS AND MEASURED BY THE FLAME TEST CONCEPT INVENTORY

by Ana V. Mayo

One challenge of chemistry education arises from the limited experiences that students have with some abstract concepts first introduced during chemistry classes. The abstract concept of atomic emission is formally introduced during secondary education in the U.S. science curriculum. The topic is re-introduced in the first year of, and elaborated upon throughout, the undergraduate chemistry curriculum. Current chemistry education literature does not address students’ understandings of atomic emission. This study addresses this gap in the literature. Through interviews, this study investigated students’ understandings of atomic emission using flame test demonstrations and energy level diagrams. In both open-ended and flame test questions, ideas related to enthalpy, ionization, and changes in states of matter were common reasoning patterns when students builded explanations for atomic emission. The misconceptions found in interviews allowed the development of the Flame Test Concept Inventory (FTCI). The FTCI was administered to high school and undergraduate chemistry students. The results of 459 high school students across the U.S and 362 undergraduate chemistry students from a predominantly undergraduate institution shed light into diverse categories of misconceptions at different levels of student chemistry expertise. While the focus of this dissertation was students’ understandings of atomic emission, additional work was completed in analytical chemistry. This work is presented in Appendix A- Flow injection analysis (FIA) and liquid chromatography (LC) for multifunctional chemical analysis (MCA) systems. The large class sizes of first year chemistry labs makes it challenging to provide students with hands-on access to instrumentation because the number of students typically far exceeds the number of research grade instruments available to collect data. MCA systems provide a viable alternative for large scale instruction while supporting a hands-on approach to more advanced instrumentation. This study describes how the capabilities of MCA systems were extended to introduce FIA and LC in undergraduate laboratories. Two MCA systems, Vernier and MeasureNet, were used in two unique experiments demonstrating the detection of salicylate in aspirin tablets by FIA and the LC separation of a mixture of riboflavin and fluorescein. Both instruments are rugged and inexpensive permitting student construction, if desired. ATOMIC EMISSION MISCONCEPTIONS AS INVESTIGATED THROUGH STUDENT INTERVIEWS AND MEASURED BY THE FLAME TEST CONCEPT INVENTORY

A Dissertation

Submitted to the Faculty of Miami University in partial fulfillment of the requirements for the degree of

Doctor of Philosophy

Department of Chemistry and Biochemistry

Ana V. Mayo Miami University Oxford, OH 2012

Dissertation Director: Stacey Lowery Bretz

Ana V. Mayo 2013

Table of Contents

Table of Contents ...... iii

List of Tables ...... xi

List of Figures ...... xiii

List of Appendices ...... xvi

Dedication ...... xviii

Acknowledgements ...... xix

Chapter 1: Statement of the Problem ...... 1

Purpose of the Study and Research Questions...... 1

Boundary Conditions ...... 2

Chapter 2: Literature Review...... 4

Constructivism……………………………………………………..…...... 4

Ausubel’s and Novak’s Meaningful Learning…………...... 4

Johnstone’s Domains for Representation of Chemistry Concepts...... 5

Misconceptions Research...... 6

Misconception related to Atomic Emission...... 8

Concept Inventories ………………………...... 8

Chapter 3: Methodology ...... 12

Rationale for Mixed Methods Design……………………………………..….… …….12

Qualitative Method Analysis……………...... 12

Interview Setting………………..………...... 14

Flame test demonstration……..………...... 14 iii

Human subjects procedures...... 15

Interviewee recruitment…...... 16

High school classes…..………...... ,...... 16

High school participants………...... 16

Undergraduate classes………...... 16

Undergraduate participants………...... 17

Context of the study...... 17

High school...... 18

Undergraduate school...... 19

Interviews...... 19

Interview technique...... 19

Interview Analysis...... 21

Constant comparative method...... 21

Constant comparative method analysis...... 22

The mode node framework...... 22

The mode node framework analysis...... 23

Quantitative data collection and analysis...... 24

Concept inventory design...... 24

Writing items...... 24

Validity...... 24

Expert Alpha FTCI Content Validity...... 24

Alpha FTCI Participant Recruitment...... 25

Alpha FTCI Student Validation Interviews...... 25

Alpha FTCI Concurrent Validity...... 26

Alpha FTCI Student Validation Interviews...... 26

Alpha FTCI Scoring...... 26

FTCI Participant Recruitment...... 27

FTCI Participants...... 27

High school participants...... 27

Undergraduate participants...... 27

Test-retest participants...... 27

FTCI Student Validation Interviews...... 28

FTCI Scoring...... 28

FTCI Item Analysis...... 29

Item difficulty...... 29

Item Discrimination...... 29

Point Biserial...... 29

FTCI Test Discrimination...... 30

FTCI Test Reliability...... 30

Internal Consistency...... 30

Test-Retest Reliability...... 30

Chapter 4: Students’ Reasoning Patterns and Misconceptions about Atomic Emission……………………….……………………….……………..…...32

Mode Node Framework Analysis...... 32 v

Example MNF analysis #1...... 32

Drawing Nodes...... 34

Example MNF analysis #2...... 35

Reasoning Patterns about Atomic Emission in Open-Ended Questions...... 37

Atoms release energy in the form of heat and light/radiation/photon...... 38

Exothermic reactions are used to explain how atoms release energy...... 38

Mixing substances (compounds/molecules/atoms/ions) produces a reaction……………..…………………………………………………..38

Breaking bonds releases energy...... 38

Forming bonds releases energy...... 39

Atoms release energy by filling orbitals/shells to obtain an octet in order to become stable...... 40

Electrons move to higher energy orbitals causing electrons to be lost/gained hence the release of energy...... 40

Reasoning Patterns about Atomic Emission using the context of a flame test...... 42

Atoms in the flame release energy when they go from solid to liquid to gas,and when they collide and speed up in the flame...... 43

The flame causes substances to melt and bonds to break to form individual atoms...... 44

Flame color depends on atoms’ temperature/ kinetic energy/movement……...... 45

Flame color is due to the lost or gained of electrons which cause the release of energy...... 46

Comparing GC and UD students in Phase I…………………………………...... 47

Comparing GC and UD students in Phase II……………………….…………...... 48

Misconceptions of Atomic Emission...... 48

Misrepresentations of atomic emission...... 48

Symbols and conventions……………………………………...... 48

Students who chose only the “up-arrow” energy level diagram…...... 52

Students who chose only “down- arrow” energy level diagram...... 54

Students who chose both energy level diagrams...... 54

Atomic properties ...... 57

Excess energy multiple color flames……………………………..…….……57

Location of elements in periodic table...... 57

Ionic Radii...... 59

Effective nuclear charge…………...... 60

Number of valence electrons………………………………...... 60

Different inner energy shells affecting energy release...... 61

Terminology used out of context………...... 62

Flame as a catalyst ...... 62

Flame as overcoming the activation energy...... 62

Flame as an indicator...... 63

Forming/breaking bonds in the flame test releases energy...... 63

Forming bonds in the flame ...... 64

Breaking bonds in the flame ...... 65

Lose electrons lose energy...... 67

Gained electrons gained energy...... 68

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Splitting subatomic particles...... 70

Summary...... 72

Chapter 5: The Flame Test Concept Inventory as a Tool to Measure Prevalent Misconceptions of Atomic Emission…………………………….……74

Validating FTCI...... 74

Expert content validation...... 74

Confusing items………………………………………...... 75

Items that best represent the concept of atomic emission...... 76

Omitted aspects of atomic emission...... 76

Concurrent Validity...... 78

Student validation interviews...... 78

Expert validation Alpha FTCI...... 82

Alpha FTCI Results...... 83

GC Descriptive Statistics...... 83

Normality Test...... 84

Item Analysis for Alpha FTCI...... 84 Item difficulty...... 84

Discrimination Index...... 85

FTCI Administration...... 86

HS Chem Descriptives...... 87

Test of normality for HS Chem...... 88

AP Chem descriptives...... 88

Test of normality for AP Chem...... 88

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GC Descriptives...... 89

Test of normality for GC...... 89

Test Discrimination...... 90

Reliability...... 90

Internal Consistency per student sample...... 90

Test-retest reliability...... 91

Item Analysis...... 93

Item Difficulty...... 93

Item Discrimination...... 95

Point Biserial ...... 98

Atomic Emission misconceptions...... 99

Misconceptions with representations...... 100

Atomic properties...... 103

Breaking and forming bonds...... 103

Losing or gaining electrons...... 104

Process related...... 105

Heuristics...... 105

Terminology used out of context...... 106

Misconception Categories within the FTCI items...... 107

Summary…………………………………………………………………………...... 109

Chapter 6: Conclusions, Implications and Future Work...... 110

Conclusions...... 110

Common Reasoning Patterns...... 110

Common misconception categories...... 111

Potential Limitations...... 113

Implications for Teaching...... 114

MNF and Class Discussion...... 114

MNF and Representations...... 115

FTCI and Assessment...... 115

FTCI and Representations...... 115

Flame Test and Student Engagement...... 116

Implications for Chemistry Education Research...... 117

Future Work...... 118

Students’ Building of Scientific Explanations...... 118

Teachers’ misconceptions about Atomic Emission...... 118

Teaching Applications...... 119

References ...... 120

List of Tables

Table 1 Undergraduate students who participated in interviews...... 17

Table 2 High school teachers’ background……………………...... 19

Table 3 HS Chem, AP Chem, and GC participant information...... 27

Table 4 Dynamic Mental Construct analysis of Phase I open-ended questions for Samuel (GC)...... 33

Table 5 Common drawing nodes (with representative examples) in Phase I...... 34

Table 6 Dynamic Mental Construct analysis of Phase II flame test questions for Lucy (UD)...... 36

Table 7 Dynamic Mental Constructs (DMC) about atomic emission...... 37

Table 8 Dynamic Mental Constructs in flame tests…………………………….....43

Table 9 Students’ choice of energy level diagram(s)...... 52

Table 10 Faculty’ teaching and area of expertise...... 75

Table 11 Descriptive Statistics for 1-tier and 2-tier GC Alpha FTCI scores...... 84

Table 12 Test of Normality for Alpha FTCI GC Distribution...... 84

Table 13 Alpha FTCI Item difficulty…………………...... 85

Table 14 Alpha FTCI Item discrimination……...... 86

Table 15 Descriptive Statistics for 1-tier and 2-tier HS Chem FTCI scores...... 87

Table 16 Test of Normality for HS Chem Distribution …...... 88

Table 17 Descriptive Statistics for 1-tier and 2-tier AP Chem FTCI scores...... 88

Table 18 Tests of Normality for AP Chem FTCI Distribution...... 89

Table 19 Descriptive Statistics for 1-tier and 2-tier GC FTCI scores...... 89

Table 20 Tests of Normality for GC FTCI Distribution...... 89 xi

Table 21 Test Discrimination Power (δ) by student sample...... 90

Table 22 HS Chem, AP Chem and GC internal consistency...... 91

Table 23 Descriptive Statistics for the 1-tier and 2-tier FTCI Test- retest Sample...... 92

Table 24 Tests of Normality for 1-tier and 2-tier Test- retest FTCI Distribution …....92

Table 25 Correlations for Test-retest...... 93

Table 26 Student Correlations for Test-retest...... 93

Table 27 FTCI item difficulty (p) by student sample...... 94

Table 28 FTCI item discrimination by student sample...... 95

Table 29 FTCI Item Reliability (ρbis) by student sample...... 99 . Table 30 Misrepresentation category...... 102

Table 31 Atomic properties category ………………...... 103

Table 32 Breaking and forming bonds category ……...... 104

Table 33 Losing or gaining electrons category …...... 104

Table 34 Process related category...... 105

Table 35 Heuristics category ……………...... 106

Table 36 Terminology used out of context category...... 106

Table 37 Misconception categories next to its assigned FTCI items...... 107

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List of Figures

Figure 1 Johnstone’s Domains…………………………...... 6

Figure 2 Student executed flame test demonstrations...... 15

Figure 3 Energy level diagrams used in interview...... 21

Figure 4 Representation of two different Modes...... 23

Figure 5 Enthalpy diagrams to explain energy release in bond Breaking (Ringo, UD)……………………...... 39

Figure 6 Formation of a compound releases energy (Samantha, UD)………….……..39

Figure 7 Energy level diagram as staircase (Samuel, GC)…………….……………...40

Figure 8 Losing electrons as part of atomic release of energy (Rachel, UD)………...41

Figure 9 Gained/loss of electrons as part of atomic release of energy (Liz, GC)…...... 42

Figure 10 Particulate representation of flame test (Ann, GC)...... 44

Figure 11 Particulate representation of the flame test (Matt, GC)...... 45

Figure 12 CuCl2 in flame test (Michael, GC)...... 45

Figure 13 Ionization during flame tests (Rachel, UD)………………………………...46

Figure 14 Atomic absorption and release of energy, (Rachel, GC)...... 47

Figure 15 Energy level diagram used in Phase III …………………………..…….…..49

Figure 16 Energy level diagrams used in Phase IV...... 51

Figure 17 Flame Test of copper (II) chloride breaks compound apart (Michael, GC)...54

Figure 18 Color of flames in flame tests of Lithium Chloride and Copper (II) chloride (Regina, GC)...... 57

Figure 19 Atomic radii related to different colored flames (Lucy, UD)………………..60

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Figure 20 Atomic representations of metals from copper (II) chloride and lithium chloride (Alex, HS Chem)……… ………………………...... ….………..61

Figure 21 Activation energy overcome by flame (Arthur, AP Chem)...... 63

Figure 22 Formation of ionic compound (Alex, HS Chem)...... 64

Figure 23 Bond formation causes release of energy (Samantha, UD)...... 64

Figure 24 Breaking ionic bonds releases energy (Arthur, AP Chem)...... 66

Figure 25 Representation of how atoms in the flame release energy (Nick, HS Chem)……………………………………………………………….……....66

Figure 26 Dissolving as release of energy (Jason, AP Chem)…...... 67

Figure 27 Losing electrons as atomic release of energy (Larry, HS Chem)…..…...... 68

Figure 28 Absorption of energy by gaining an electron (Samantha, UD)...... 69

Figure 29 Absorption of energy by losing electrons and subshells (Samantha, UD...... 69

Figure 30 Atomic shrinkage by release of energy (Annie, HS Chem)...... 70

Figure 31 Lithium atoms when electrons are gained and lost (Marina, AP Chem)……70

Figure 32 Splitting subatomic particles release energy during flame tests (Darren, HS Chem)……………………………...... …71

Figure 33 Atoms releasing energy by collision (Elizabeth, HS Chem)...... 71

Figure 34 Subatomic particles splitting (Susan, AP Chem)...... 72

Figure 35 Modification of item based on expert commentary...... 75

Figure 36 Modified diagram based on expert feedback to improve the validity...... 76

Figure 37 Item added to Alpha FTCI per expert suggestion (1)...... 77

Figure 38 Item added to Alpha FTCI per expert suggestion (2) ……………………...77

Figure 39 Item modified based on student feedback...... 79

Figure 40 Modified item based on student’s feedback (1)………………………….….80 xiv

Figure 41 Modified item based on student feedback (2)...... 81

Figure 42 Modification of an item based on expert commentary...... 82

Figure 43 Item added based on students’ written responses...... 83

Figure 44 Distribution of GC total scores on Alpha FTCI (n=222)...... 84

Figure 45 Alpha FTCI Discrimination and Difficulty Plot...... 86

Figure 46 HS Chem distribution for 1-tier and 2-tier scores...... 87

Figure 47 AP Chem distribution for 1-tier and 2-tier scores...... 88

Figure 48 GC distribution for 1-tier and 2-tier scores...... 89

Figure 49 HS Chem FTCI Discrimination and Difficulty Plot………………………..97

Figure 50 AP Chem FTCI Discrimination and Difficulty Plot……………………..…97

Figure 51 GC FTCI Discrimination and Difficulty Plot...... 98

Figure 52 Item with Bohr atomic model in FTCI...... 100

Figure 53 Limitations of the Bohr atomic model item in FTCI ……..……………....101

Figure 54 Item with energy level diagram used in FTCI...... 101

Figure 55 Reason-tier item for energy level diagram representation ……..………...102

Figure 56 Percent HS Chem students with number of misconception categories...... 107

Figure 57 Percent AP Chem students with respective number of misconception categories…………………………………………………………...……...108

Figure 58 Percent GC students with respective number of misconception categories.108

List of Appendices

Appendix A- Cognate Manuscript for Journal of Chemical Education...... 132 A.1- Supplementary Materials FIA student ...... 143

A.2- Supplementary Materials FIA teacher ...... 154

A.3- Supplementary Materials LC student...... 166

A.4- Supplementary Materials LC teacher...... 177

A.5- Permission to use MeasureNet Website Pictures...... 191

A.6- Permission to use book diagram...... 192

Appendix B- Flame Test Demonstration...... 194

Appendix C- IRB 1st approval...... 195

Appendix D- IRB 2nd Approval...... 197

Appendix E- Student Informed Consent Form...... 198

Appendix F- High School Principal Consent...... 199

Appendix G- Parent Consent Form...... 200

Appendix H- Informed assent script for minor student participant...... 201

Appendix I- Exempt from Undergraduate IRB Review...... 202

Appendix J- Exempt from High school IRB Review...... 203

Appendix K- Interview Guide...... 204

Appendix L- Interview Transcript...... 209

Appendix M- Coding sample...... 223

Appendix N- Sample MNF analysis of Samuel, a GC student during Phase I...... 224

Appendix O- Sample MNF analysis of Lucy, a UD student during Phase II……...... 226

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Appendix P- Sample Writing of an Item……………………………………..……...... 228

Appendix Q- Inventory Expert Validation Informed Consent Form...... 233

Appendix R- Expert Alpha Flame Test Concept Inventory...... 235

Appendix S- Alpha Flame Test Concept Inventory (Alpha FTCI)...... 240

Appendix T- Think Out-loud Protocol ………………………………………………….…...... 244

Appendix U- Instructor’s signed permission for administering inventory (Sample)….…..…...... 252

Appendix V- Invitation to participate in Chemistry Concept Inventory Project…...... 253

Appendix W- Final version of FTCI...... 255

W.1- Color Handout of FTCI...... 261

Appendix X- Instructor’s directions for administering concept inventory…...... 262

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Dedication

For Ashly and Cristior

xviii

Acknowledgements

They are many people who have influenced and supported me through this dissertation. I will be forever grateful to Dr. Stacey Lowery Bretz, my advisor and mentor, for believing in me at all times and for imparting the tools I need to stand on my own as a researcher and as an instructor. I would like to acknowledge Dr. Neil Danielson; our many discussions taught me a different way to see research and mentoring, and his passion for science is always transparent in his work. I would like to thank Dr. Ellen Yezierski, for her advice and support. I will try to emulate her energetic outlook towards work. I would like to acknowledge Dr. Jerry Sarquis for being an advisor through his many discussions about the field of CER. His views towards teaching and research have also allowed me to form my own. I would like to extend thanks to Dr. Richard Taylor and Dr. Jennifer Blue, members of my committee, for their genuine interest and support of this work.

I would also like to thank the former and present members of the Bretz’s and Yezierski’s CER groups, for their helpful insights during group meetings, in practice talks and even outside of the office. Thanks to Dr. Mary Emenike, Dr. David Sanabria Rios, Dr. Kim Linenberger, Dr. Lakeisha McClary, Brittany Christian, Allie Brandriet, Cynthia Luxford, Jana Jensen, Michael Bindis, Kelli Galloway, Justin Carmel, Jordan Harshman, and Sara Nielsen. I would like to give thanks to Dr. Gabriela Szteinberg for her support and friendship. I also would like to give thanks to Lucy Manley, and Ann Showalter for helping me improved my writing skills. I would like to thank the students I had the privilege to teach whom by sharing their struggles and resilient spirit inspired me to switch careers from chemistry to education. Lastly, I would like to thank my family, Ashly and Cristior, my children, your presence is my motivation to do the best I can and for whom I become a better person. And, thanks to Daniel, my husband. Your support is immense, and your love for science, I admire. Thank you for being my best friend.

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CHAPTER 1: STATEMENT OF THE PROBLEM

One challenge of teaching and learning chemistry arises from the limited experiences that students have with many of the abstract concepts to be learned prior to formal instruction in chemistry (Johnstone, 2000). The abstract concept of atomic emission is formally introduced during secondary education in the U.S. science curriculum. According to the National Science Education Standards (Council, 1996) the concepts of atomicity, energy transfer, types of radiation, and the absorbance and scattering of light by objects are introduced to students in 5th- 8th grades. In the secondary science curriculum, students learn about multi-atomic models (Harrison & Treagust, 2000) and energy level diagrams (College Board, 2012). Quantum principles are taught more extensively in the first year of undergraduate chemistry and physics classes (Taber, 2005) and elaborated upon throughout the undergraduate curriculum. Chemistry education research regarding ideas related to atomic emission, such as orbitals (Cervellati & Perugini, 1981; Taber, 2005; Tsaparlis & Papaphotis, 2009) and Bohr atomic models (McKagan, Perkins, & Wieman, 2008), has revealed student misconceptions about representations in particular. The study of teaching with external representations has discussed a variety of challenges in student learning (Pintó & Ametller, 2002; Schnotz, 2002), including, for example the occurrence of cognitive dissonance when students encounter multiple representations (Linenberger & Bretz, 2012). For example, Orgill and Crippen (2010) recently gave students chemistry problems that could be solved using either equations or energy level diagrams, both of which were provided. The majority of students preferred to use equations to arrive at solutions, rather than the representations of energy level diagrams (Orgill & Crippen, 2010). The chemistry education literature is silent, however, with regard to students’ understandings of atomic emission. This study addresses this gap in the literature.

Purpose of the Study and Research Questions The purpose of this study was to investigate students’ ideas of atomic emission in interviews using flame test demonstrations and energy level diagrams. This study also aimed to develop a concept inventory grounded in qualitative analysis of student interviews. Lastly, the misconceptions found in this study were examined by means of the analysis of the Flame Test

Concept Inventory (FTCI) at different levels of student expertise, namely high school and first year undergraduate chemistry classes. Below, there are the specific research questions explored:

1. What reasoning patterns develop in students’ explanations of atomic emission a) during open-ended questions? b) in the context of explaining flame test phenomena? 2. What prevalent student misconceptions exist about atomic emission?

Boundary Conditions This study examined students’ understanding of how light interacts with matter. Specifically, it targeted the students’ insights into the behavior of electrons in atoms and how atoms give off characteristic colors of light. This is investigated by analyzing if a student could explain that (a) electrons exist only in certain energy levels and that energy can be absorbed or release by atoms only in discrete amounts. Planck gave the name ‘quantum’ (fixed amount) to the smallest quantity of energy that can be absorbed or emitted as electromagnetic radiation; (b) energy must be absorbed for an electron to move from a lower energy level (ground state) to a higher energy level (excited state). And energy is emitted when an electron moves from a higher energy level to a lower energy level. This assumes that the electron cloud ‘jump’ (postulated by Bohr) happens from an allowed energy state to another by absorbing or emitting photons whose energy corresponds exactly to the energy difference between the two states; (c) the energy difference between the two states correspond to the wavelength of light (visible color) emitted in the flame test (d) the understanding of representations commonly used in textbooks such as energy level diagrams, and Bohr atomic models; (d) the representation of electronic transitions (arrows) using Bohr atomic models and energy level diagrams; (e) understanding the limitations of the Bohr atomic model: this model offers a representation for H-like atoms but cannot explain multi-electron atoms, and often representations of the Bohr atomic model shows energy levels that are equidistant to each other. This study does not include the following: (a) understanding of the relationships between energy, frequency, and wavelength of electromagnetic radiation; (b) the wave properties of matter, and the knowledge that it is impossible to determine simultaneously the exact position and exact motion of an electron in an atom (Heisenberg’ uncertainty principle); (c) the electron

2 arrangement within atoms that can be described by quantum mechanics in terms of orbitals and quantum numbers; (d) the representation of orbitals; (e) the understanding of orbital energies; or (f) electron configurations.

CHAPTER 2: LITERATURE REVIEW

This chapter reviews the literature relevant to this study. Five areas were included: (1) Constructivism; (2) Ausubel and Novak’s theory of meaningful learning; (3) Johnstone’s domains for representation of chemistry concepts; (4) Misconception Research, and (5) Concept inventories.

Constructivism From a constructivist perspective, a student’s prior knowledge is considered one of the most significant factors in teacher planning (Ausubel, 2000; Fensham, White, & Gunstone, 1994). The constructivist view of personal knowledge assumes that all knowledge is acquired in relation to the learner’s prior knowledge, experiences, and events (Bodner, Klobuchar, & Geelan, 2001). This prior knowledge needs to be elicited by instructors before instruction takes place; and the new information can be assimilated and accommodated in the mind of the learner. This accommodation is possible if the learner is made aware of any differences between his/her prior knowledge and the new knowledge (Baviskar, Hartle, & Whitney, 2009; Bodner et al., 2001). Chemistry Education Research (CER) borrows from the constructivist view that the pursuit of how students are aware of these differences between what they know and what the need to know in chemistry classes. The constructivist view shifts the idea of a teacher just lecturing in front of class to a teacher facilitating learning by taking into account students’ prior understanding. Constructivist CER also requires that the student is an active participant in his/her learning, constructing and modifying knowledge (Bodner, 1986). In keeping with the constructivist approach, this study searched for the differences between students’ constructed knowledge, understanding and misconceptions about atomic emission after class instruction and curriculum based understanding of this concept. Student interviews were used to elicit misconceptions and misunderstanding of representations of atomic emission.

Ausubel’s and Novak’s Meaningful Learning According to Ausubel, learning will be meaningful only when the new idea or concept to be learned can be purposefully connected to the student’s relevant concepts and ideas which have

4 been acquired previously (Ausubel, 1968; Bretz, 2001). This framework is consistent with a constructivist approach to learning, namely that students construct meaning through the lens of their prior knowledge, adjusting and rebuilding their knowledge as they learn. Novak’s human constructivism indicates that students need to have experiences across the cognitive, psychomotor, and affective learning domains to be able to construct knowledge that is meaningful as Ausubel indicated (Bretz, 2001; Novak, 1984). Novak’s theory describes these experiences within the cognitive, psychomotor, and affective learning domains as: the cognitive domain includes what a learner knows and rationalizes about a topic, the affective domain includes how a learner feels (attitudes) about the topic, and the psychomotor domain includes what a learner does with his or her knowledge. That is learning chemistry meaningfully should integrate across these domains. As students construct their knowledge, misconceptions are likely to arise from this process. One way that misconceptions arise comes from Driver’s studies in which students were often unable to see that the results of an experiment should have refuted their ideas about what was going on; instead they recorded what their pre-conceptions told them what was going on in the experiment (Driver, Guesne, & Tiberghien, 1985). The meaningful learning domains of Novak were incorporated into the research methodology of this study. The methodology investigated not only what students thought about the behavior of atoms as the release energy (cognitive), it also allowed students to conduct flame tests demonstrations to visualize how three different salts of chloride emit energy (psychomotor).

Johnstone’s Domains for Representation of Chemistry Concepts According to Johnstone, chemistry concepts are represented by three domains, namely a macroscopic domain (the tangible or visible), a particulate domain (the invisible), and a symbolic domain (representations) (Johnstone, 2009). Johnstone states that in formal science classrooms, students are expected to understand the connections between all the domains, but this understanding is challenging for students (Johnstone, 1991). The domains for a concept, such as atomic emission, can be represented with a triangle in which each corner corresponds to a domain and the connections between domains are represented by the sides of the equilateral triangle (Figure 1). The triangle is also a useful tool for estimating the load being placed on students’ working memory during teaching and learning. This is due to the multiple macroscopic,

5 particulate, and symbolic representations of chemistry concepts. A commonly agreed source of student misconceptions is the inability of students to make connections among the different levels of representations in Johnstone’s domains (Gabel, 1999; Gabel & Bunce, 1994; Kozma & Russell, 1997). Many studies have used one or more of Johnstone’s domains with the intention to help students overcome these difficulties, for example a recent study that created computer animations as means to develop a concept inventory (Wei, Liu, Wang, & Wang, 2012). Another recent study analyzed student cognitive dissonance produced while using similar representations for the same concept (Linenberger & Bretz, 2012). The present study applied Johnstone’s domains to the choice of prompts used in the interviews, namely flame tests and energy level diagrams, which represent two of the three domains. The students’ explanations gathered during interviews provided a means to document misconceptions about atomic emission at the macroscopic, symbolic, and particulate levels of understanding.

Figure1. Johnstone’s Domains. Adapted from Johnstone, A.H (2009).

Misconceptions Research Many terms have been assigned to this type of research, among them: naïve beliefs, preconceptions, alternative conceptions, erroneous ideas, multiple private versions of science, and prescientific conceptions (Wandersee, Mintzes, & Novak, 1994). In this study, the term

‘misconception’ has been adopted because it has meaning to the layperson, and in science education it conveys the concept of an idea that differs from the one accepted in science. Misconceptions can be found by studying learners’ ideas prior to formal science instruction. For example, Rosalind Driver’s studies focused on children’s preconceived notions (Driver et al., 1985). Children behaved as scientists in the way they searched for patterns and formed assumptions to explain these patterns. The problem was the way children treated data. Driver found that children were unable to see that the results of an experiment should have refuted their ideas about what is going on; in fact they recorded and reported results in accord with their preconceived ideas (Driver, 1983). Literature shows that novice learners make some sense of what they are told, and use whatever resources are available in terms of existing conceptions in order to interpret information into something meaningful (Taber, 2001). A large portion of misconception research investigates student understanding of concepts after they have been formally introduced and assessed at school because this reveals deeply rooted misconceptions that remain even after instruction. Chemistry misconception studies cut across cultural boundaries. For example, Tan et al conducted a cross cultural study on ionization energy misconceptions in students from the U.K., Singapore, the U.S., China, New Zealand, and Spain. The study showed that all six sample populations from different countries and education systems had similar misconceptions about the concepts assessed (Tan et al., 2007). The widespread occurrence of misconceptions across diverse populations and cultures suggests that these misconceptions might be caused by common cultural experiences such as the direct observation of nature, the use of language, the portrayal of science by the media, and the use of prevalent instructional practices (Wandersee et al., 1994). Misconceptions also arise from historical models that continue to be used today in chemistry because they provide some type of instructional value (Taber, 1995). For example, models such as the Bohr atomic model (McKagan et al., 2008) and orbitals (Tsaparlis & Papaphotis, 2002) are introduced to illustrate the nature of science and show how scientific ideas are revised with new data. While these models have historical value, once students are introduced to them, they have difficulties understanding new models. The acquisition of so many chemistry-specific ideas, such as atoms and electrons, are likely to have occurred through formal chemistry teaching. Therefore, teachers could have held many misconceptions that they then transfer to students (Mulford & Robinson, 2002). An

example of this is found in a Singapore study about ionization energy that compared and showed that pre service high school teachers and high school students’ misconceptions highly matched (Tan & Taber, 2009).

Misconceptions related to Atomic Emission Currently, there are no studies on atomic emission misconceptions, but studies related to the topic of atomic emission are found in science education literature. Among misconceptions related to atomic emission such as the topic of orbitals, research suggests that students at college level have difficulties learning about quantum-mechanical models of the atom with electrons ‘located’ in orbitals, which are defined in terms of probability, and are not subject to well- defined boundaries (Cervellati & Perugini, 1981; Taber, 2005; Tsaparlis & Papaphotis, 2009). A study done with 12th grade Greek students recommends the omission of teaching the concept of orbitals to secondary chemistry students because of the critical thinking required to understand their probabilistic nature (Tsaparlis & Papaphotis, 2002). Other studies showed that learners have difficulties in developing scientific models of chemical structures, atoms, molecules, and lattices (Taber, 2001; Tsaparlis, 1997). Another study, conducted with college physics students, presents that teaching the Bohr model is not an obstacle for learning the Schrödinger model of the atom. The Bohr model, De Boglie, and the Schrödinger models were taught to students in the study. The results showed that students’ descriptions of atoms lack understanding of the limitations of each model (McKagan et al., 2008). To add to the research and practice in the field, concept inventories are research based tools that instructors can use to elicit student misconceptions in an efficient manner in class.

Concept Inventories A concept inventory (CI) can be defined as a multiple-choice assessment ideally designed for learner focused purposes (Libarkin, 2008). CI design could include items with one or more tiered questions. Single-tier CIs work well with questions that require understanding of abstract concepts (Adams & Wieman, 2011; Bretz & Linenberger, 2012). Two-tier CIs are appealing because they separate a factual knowledge (Tier 1=facts) from reasons for choosing a particular fact (Tier 2= mechanism and beliefs). This works well for simple concepts when students’ understanding might only be rote-memorization (Anderson, Fisher, & Norman, 2002;

Chandrasegaran, Treagust, & Mocerino, 2007; Treagust, 1988). CIs with more than two tiers, have added confidence scale tiers to each of the first and second tier items. The confidence scales asks students to appraise his or her performance on each item in order to distinguished correct answers based on guessing and correct answers based on genuine understanding (Caleon & Subramaniam, 2010; McClary & Bretz, 2012). A limitation of a multiple tier test that includes a confidence scale is that it requires a longer test time for administration and it could produce fake student responses influenced by social pressure (Lundeberg, Fox, & Brown, 2000). There are many CIs that assess multiple chemistry concepts. The Concept Chemistry Inventory (CCI) includes topics of bonding, intermolecular forces, acids and bases, electrochemistry, equilibrium, and thermochemistry (Mulford & Robinson, 2002). The Nature of Solutions and Solubility Diagnostic Inventory (NSS-DI) includes various concepts related to solution chemistry (Adadan & Savasci, 2012). Othman’s inventory investigates how the understanding of the particulate nature of matter influenced the understanding of chemical bonding (Othman, Treagust, & Chandrasegaran, 2008). Some CIs focus on a particular concept or narrow theme, among them, a computer modeling instrument to assess macroscopic, submicroscopic, and symbolic representations of matter (Wei et al., 2012). The Enzyme– Substrate Interactions Concept Inventory (ESICI) measures student understanding of enzyme– substrate interactions in biochemistry courses (Bretz & Linenberger, 2012). McClary and Bretz developed an inventory to identify organic chemistry students’ misconceptions related to acid strength (McClary & Bretz, 2012). Finally, the Implicit Information from Lewis Structures Instrument (IILSI) determines whether students are making essential connections between structures and their properties while using Lewis structures (Cooper, Underwood, & Hilley, 2012). When students construct a coherent understanding of phenomena after formal instruction that does not match acceptable scientific views, then misconceptions are formed. These misconceptions, if not challenged in class, become integrated into students’ cognitive structures and interfere with subsequent learning of new concepts (Treagust, 2006). Instructors can elicit misconceptions by implementing CIs as a formative assessment of students’ understanding of a concept or multiple concepts. Formative assessment occurs during teaching; it is a way of assessing students’ progress, providing feedback, and making decisions about instructional activities (McMillan, 2011).

A CI can also measure aspects of student thinking; this information allows instructors to distinguish between novice- and expert- like thinking in their classrooms. It also provides a way to compare instruction across institutions in a calibrated manner (Adams & Wieman, 2011). A CI developer’ goal is to make a reliable instrument that is easy to use, administered in a short period of time, and can accurately identify students’ misconceptions (Krause, Birk, Bauer, Jenkins, & Pavelich, 2004). Chemistry CIs have been developed from misconceptions already published in the literature where the developers craft their own questions using existent qualitative results, for example, the phase equilibrium concept test (Azizoglu, Alkan, & Geban, 2006). Other CIs have been developed from student interviews, among them: a written inventory to diagnose misconceptions about covalent bonding and structure from student-drawn concept maps, student interviews, and free-response questions (Peterson, Treagust, & Garnett, 1989). The ESICI utilizes student interviews and student-drawn representations (Linenberger & Bretz, 2012). The National Research Council’s study of assessment recommends the use of student interviews in the development of CIs (National Research Council, 2001). Interviews provide qualitative data that developers can use to formulate attractive distractors written in the natural language of students, thus ensuring that the test elicits common students’ ideas and their difficulties with reasoning (Sadler, 1998). Concept inventories that use student interviews to develop distractor-driven multiple choice tests are said to have a mixed-method design. A mixed-method design (Towns, 2008) combines the advantages of qualitative research with the benefits of quantitative assessment, which allows the generalization of misconceptions to a greater population. In this dissertation, the methodology employed was a mixed-method design. This study included the analysis of student interviews and student-drawn representations from diverse populations: high school, first year, and upper division chemistry students. The inventory developed by the researchers, the Flame Test Concept Inventory (FTCI), has mixed-style format items that include both 1-tier and 2-tier items. It focuses on a specific chemistry concept: atomic emission in the context of flame tests demonstrations. Chemical Education Research (CER) has two main perspectives: the social perspective of the process of learning and the analytical perspective of the content of chemistry. This marriage between a social science (learning process) and a physical science (chemistry) facilitates the

10 emergence of experiments where it is difficult to control all variables that can affect the achievement and performance in chemistry (Herron & Nurrenbern, 1999). These two perspectives are woven within this dissertation as shown in the following chapters: Methodology (Chapter 3), Students’ Reasoning Patterns and Misconceptions about Atomic Emission (Chapter 4), FTCI as a Tool to Measure Prevalent Misconceptions of Atomic Emission (Chapter 5), and Conclusions, Implications and Future Work (Chapter 6).

CHAPTER 3: METHODOLOGY

This chapter presents the mixed-method design chosen for the study. Then, a discussion of the qualitative research methods use for the analysis of student interviews is presented. Lastly, a description of the quantitative method used for the development of the Flame Test Concept Inventory (FTCI) is shown.

Rationale for Mixed-Methods Design As with all research, there are certain limitations to using either a qualitative or quantitative design approach. One limitation of a qualitative research method is that the qualitative analysis results are based on local conditions which represent only a limited number of participants. It would take multiple studies of this kind to construct generalizable conclusions. On the other hand, qualitative research can provide a comprehensive and exhaustive examination of data and provides a means by which to interpret and make conclusions about the phenomena under investigation. In this study, a qualitative approach is used by obtaining student interviews. If used alone, quantitative research methods prohibit a deeper understanding of students’ ideas. However, a quantitative approach allows searching for correlations in students’ responses among different populations. In a very general sense, a measuring instrument, in this case a concept inventory, is valid if it does what is intended to do (Nunnally, 1967). A measuring instrument is said to have a high reliability if it produces similar results under consistent conditions. In this study, a quantitative approach is used to see if the findings in students’ interviews can be applied to a larger student population. This generalization will strengthen the validity of the data generated by the concept inventory. Every item in the concept inventory contains one best answer and three incorrect answers or distractors that came from student interviews. Therefore a mixed- method design was used to balance the inherent strengths and weaknesses of each research methodology (Towns, 2008).

Qualitative Research Method Analysis A goal of qualitative research is to allow the researcher to gain access to the perspective of the research subject, by allowing the meanings of participants to surface (Bretz, 2008). In this

study, the source of the perspective’s participants was obtained by conducting clinical interviews at a secondary and a post-secondary school. A clinical interview is defined as a “one-on-one encounter between an interviewer, who has a research agenda, and a subject. The interviewer proposes usually problematic situations, or issues to think about and the interviewee is encourage to engage these as best he/she can” (diSessa, 2007). Clinical interviews generate qualitative data and are commonly used in chemistry education research (CER) (Oliver-Hoyo & Allen, 2006; Phelps, 1994). Although interviews have been an invaluable tool in education research, they have also been the target of criticism for their use in constructivist approaches to research (Halldén, Haglund, & Strömdahl, 2007) and for their qualitative nature (Phelps, 1994). diSessa summarizes three such major criticisms: the white room investigation, the coercive and/or seductive practice, and the questionable invariance of knowledge (diSessa, 2007). First, the white room investigation refers to interviews taking place with subjects removed from their “native habitat,” creating a threat to ecological validity. The second criticism is the coercive and/or seductive practice of the interviewer’s questions leading to the recall of non-existent knowledge (Loftus, 1980), which occurs when the concept asked is unfamiliar to the student or when students are led to retract or revise an answer because of leading interview questions. The third criticism, questionable invariance of knowledge, refers to knowledge that may be situation specific, but may not be representative of the individual. For example a student’s answer may vary according to the type of question, open-ended ‘what can you tell me about atomic emission?’ or contextual ‘what happens to the atoms in the flame test’. diSessa continues to respond to each criticism by providing suggestions from his experience doing science education research. For example, the research setting might be unfamiliar, but if the cognitive task proposed is familiar to the interviewee, the interview may have a degree of ecological validity. This familiarity with the task is important for the establishment of mutual engagement; an understanding that provides grounds for inquiry during interviews, where the interviewee allows the interviewer to choose the manner of how the interview will be approached. Interviews in education research aim to establish understanding of student knowledge, by proposing open-ended questions, providing 2-D and 3-D prompts, or demonstrations to elicit student responses (Linenberger & Bretz, 2012). Qualitative researchers are cautious about generalizing their findings, so they draw conclusions using some form of triangulation (Nyachwaya et al., 2011; Oliver-Hoyo & Allen, 2006), e.g. comparing

what students said in interviews to an analysis of student-generated drawings in order to better understand students’ responses. In light of exercising good practices, interviews in the present study have three main characteristics: they were conducted in a laboratory setting at the students’ institution (ecological validity), used a semi-structured protocol that permitted the researcher to ask probing questions only when needed to clarify students’ explanations (non-coercive questioning techniques), and used both open-ended and context questions by allowing students to experience flame tests demonstrations.

Interview Setting The “the white room” investigation criticism warns social cognitive studies against taking human beings out of their “native habitat”. When subjects are taken into exotic context to investigate cognitive processes that are supposed to operate in school, there is a room for creating inappropriate attributions to subjects and lack of ecological validity (diSessa, 2007). In this study, ecological validity is retained by interviewing students in a familiar instructional laboratory at their own school or in a natural setting (Creswell, 2007). Both, high school and undergraduate school facilitated the use of an instructional laboratory for interviews.

Flame Test Demonstration The limited experiences that students have with many of the abstract concepts to be learned prior to formal instruction in chemistry is one of the challenges chemistry educators face (Johnstone, 2000). Educators look for ways to intrigue and engage students, and one of these ways is the use of in-class demonstrations. Demonstrations can be useful for creating cogent mental links between chemistry concepts and real world applications, initiating class discussions while creating personal relevance to the topic at hand, and encouraging collaboration between students and instructors to ask questions and seek ad-hoc solutions (Meyer, Panee, Schmidt, & Nozawa, 2003). The flame test is a demonstration used as a visual representation of atomic emission in chemistry classes. While there are many versions of the flame test that provide clear procedural instructions (Ager, East, & Miller, 1988; Dragojlovic & Richard, 1999; Gouge, 1988; McKelvy, 1998; McRae & Jones, 1994), connections to the concept of atomic emission, are not typically discussed within these papers.

In this study, the flame test demonstration was chosen as a prompt during student interviews because of its popularity and rapid results while executing it. Students were given three compounds in their powder form, copper(II) chloride, lithium chloride, and sodium chloride. The procedure followed was simple (Appendix B), a student used wet wooden sticks to gather some of the compound to be put under the flame of a Bunsen burner. The results were seen immediately as the flame changes color according to the compound used (Figure 2).

copper (II) chloride lithium chloride sodium chloride

Figure 2. Student executed flame test demonstrations.

Human Subjects Procedures This study was approved by the Miami Institutional Review Board (IRB) for Human Subjects Research. The purpose for obtaining an IRB is to ensure that the rights of all human subjects are protected in accordance to federal regulations. A key requirement is to ensure that all participants provide an informed consent. This informed consent includes important aspects of the study such as confidentiality of student responses, voluntary participation, consent to audio/video recordings and secure storage records. IRB approvals for student interviews during the qualitative data collection, administration and validation interviews of concept inventory, were obtained at two different times (Appendices C and D). A sample of the undergraduate student informed consent for interviews is shown in Appendix E. Also, since the researcher interviewed minors at a high school, first the school principal’s consent was obtained in order to have access to teachers and students (Appendix F). Minors, students under 18 years of age, cannot give informed consent therefore parental permission was requested and obtained. The parental permission sample is shown in Appendix G. Also, all minors were asked to verbally assent consent before interviews took place; a sample of student assent is found in Appendix H. IRB exemptions were obtained for undergraduate and high school institutions when administering the final version of the concept inventory (Appendices I and J). These IRB exemptions were obtained because the concept inventories given to high school and

undergraduate students were anonymous and did not solicit student demographic information, only their responses to the concept inventory.

Interviewee Recruitment High School Classes High school classes were selected given their coverage of the concept of atomic emission. The recruitment of high school students was a challenge. Logistic issues arose from scheduling interviews without disrupting student class schedules. The majority of interviews took place after school dismissal times with students who had parental permissions and a ride home. For recruitment purposes small incentives were offered. A small incentive does not affect results according to a study done on different types of incentives for research purposes (Grant & Sugarman, 2004). The incentives offered, for both the student and teacher, were approved by Miami University Institutional Review Board (IRB). In this study, high school teachers who participated received a $100 gift card for the Flinn store as an incentive to help the researchers recruit students from their classes. Students who participated in interviews received a $15 gift card for the i-Tunes store. During recruitment the researcher visited the high school classrooms to explain the purpose of the study to all students. This explanation was presented to students as an opportunity to participate in chemistry education research, and the incentive was offered as a token of gratitude for their participation.

High school participants There were fifty-two chemistry student interviews. The high school sample was composed of 12 Chemistry I (HS Chem I) and 14 Advanced Placement Chemistry (AP Chem) high school students from a large suburban public high school in the midwestern United States (U.S.) during spring 2011 semester. All volunteers secured parental permission and verbal assent to consent to be interview and audio/video tape. No demographic information was collected from high school interviewees.

Undergraduate Classes Undergraduate classes were selected given their coverage of the concept of atomic emission. The researchers obtained instructor’s consent to gain access to undergraduate students

16 enrolled in their classes. Undergraduate students who volunteered to participate in the study needed to be at least 18 years old and did not receive any incentives to do so. All volunteers signed the student inform consent form and provided demographic information.

Undergraduate Participants The college population was composed of 14 general chemistry (GC) students and 12 upper division (UD) chemistry students enrolled at a large, public and predominantly undergraduate institution in the midwestern U.S., during the fall 2010 and spring 2011 semesters. UD students were enrolled in either an instrumental analysis or an analytical chemistry class. Demographic information was collected from volunteers (Table 1).

Table 1. Undergraduate students who participated in interviews

Demographics GC UD Total

Male 5 8 13 Gender Female 9 4 13 Caucasian/White 10 11 21 Ethnicity Asian/Pacific Islander 3 1 4 African American/ Black 1 0 1 Freshman (first year student) 14 0 14 Year Sophomore (second year student) 0 2 2 Junior (third year student) 0 10 10 Chemistry 0 10 10 Zoology 9 0 9 Undergraduate Biochemistry 1 2 3 Major Engineering 3 0 3 Undeclared 1 0 1 High school Yes 13 12 25 chemistry No 1 0 1

Context of the Study One-on-one interviews were conducted with two distinct student samples, high school and undergraduate chemistry students. For this, the educational context of each is presented below.

High school The high school in this study required teachers to obtain five graduate credits hours every five years to maintain teacher certification in the state; the eligible credit hours can be obtained from education or science classes. High school students interviewed were enrolled in a one-year class named Chemistry I (HS Chem I), during their 10th grade year. Advanced Placement chemistry students interviewed were enrolled in a one-year class named AP high school Chemistry (AP Chem), during their 11th grade year. The school required all students to a take a one-year Biology class in the 9th grade year and a one-year physical science class in the 10th grade year (this could be a Chem-Physics class or Chem I or Honors Chemistry or any other physical science elective). Algebra II was a co- requisite for HS Chem I. Then students at this school needed to take a one-year of an elective science class in the 11th and 12th grade years. The most popular choices were HS Chem I and Physics classes because of college admissions requirements and the honors diploma consideration for this school. The high school teachers provided information about their teaching experience, (Table 2) HS Chem I students were instructed about electronic configuration, Aufbau diagrams, electron arrangement in atoms, ground state, excited state, quantum numbers, atomic spectra, hydrogen spectrum including the Lyman, Balmer and Paschen series, and they executed a laboratory named the “flame test lab.” AP Chem students were instructed about electronic configuration using Aufbau diagrams, Hund’s rule, and the Pauli Exclusion Principle, writing electronic configuration for elements and ions, orbitals: shape, degenerate energies, number per energy level, absorption and emission of light, ground and excited states, visible and non-visible emission of light, equations associated

with atomic structure, writing quantum numbers for elements (n, l, ml, ms), and the Bohr atomic model. They also performed flame tests of Li, Na, K, Ca, Sr, Ba and Cu in the laboratory.

Table2. High school teachers’ background HS Chem I teacher AP Chem teacher Education -B.A Science Education -B.S.Ed. Comprehensive Certification Background -Master in Biological sciences (secondary education) -Master in Biology Teaching 15 years teaching HS Chem I 14 years of teaching HS Chem I classes experience classes 11 years of teaching AP Chem classes (Overall 17 years of teaching chemistry)

Undergraduate School The undergraduate school is located in the midwestern United States. It is considered to have high research activity and a predominantly undergraduate student population (Carnegie, 2012). GC chemistry students were lecture about atomic spectra, wave particle duality, quantum theory, the hydrogen spectrum, the Bohr Model, quantum numbers, electron spin, the sizes and shapes of atomic orbitals, multi electron atoms, the Aufbau principle, electron configurations, sizes of atoms and ions, and ionization energies. UD chemistry students in the Instrumental Analysis classes were taught several spectroscopy techniques, such as atomic absorption, atomic emission, UV-Vis absorption, as well as molecular, infrared, fluorescence and Raman spectroscopies. UD chemistry students in the Analytical Chemistry class were taught the fundamentals of spectrophotometry and atomic spectroscopy.

Interviews Interview technique A post- Piagetian interview technique was used in this study The interviews followed a four-phase, semi-structured protocol (Appendix K) that permitted the researcher to ask probing questions when needed to clarify students’ explanations. The interviews took place in an instructional laboratory. The high school student interviews were obtained during the fall 2010 and spring 2011 semesters, and each lasted an average of one hour. The undergraduate student interviews were obtained during fall 2010, spring and fall 2011, and each lasted an average of 45 minutes.

Enrolled high school and undergraduate chemistry students were asked both open-ended and context questions as a means to elicit student misconceptions. The context questions focused on student responses about flame test demonstrations using the Predict-Observe-Explain (POE) questioning techniques (White & Gunstone, 1992). The interviews consisted of four Phases: (1) Phase I featured open-ended questions about atomic emission. Students were also asked to create representations that included explanations of how atoms release energy. This Phase gave students time to think about the topic openly. They were provided with a periodic table, a digital pen (Livescribe Pulse ™ Smartpen (Livescribe, 2012) and paper to draw if desired (Linenberger & Bretz, 2012). (2) Phase II included student directed Flame Test demonstrations where students predicted, observed and then explained what happened to the atoms of three salts of chloride, copper(II) chloride, lithium chloride and sodium chloride, during their respective flame test. The flame test prompts were used to elicit student misconceptions about atomic emission at the level of the macroscopic domain of Johnstone’s triangle. The prompts also serve to elicit student connections, if any, between the macroscopic and particulate domains of the target concept. (3) In Phase III, students were given an energy level diagram (a) (Figure 3). With this diagram students were asked about conventions and symbols most likely found in an energy level diagram; for example, the meaning of n (principal quantum number), and the horizontal lines (energy levels). This phase informed the researcher as to how students interpret the conventions most commonly used in an energy level diagram. This phase corresponded to the symbolic domain of Johnstone’s triangle.

(a) (b) (c) Figure 3. Energy level diagrams used in interview. Adapted from Chemistry: The Molecular Nature of Matter and Change, page 257 (Silberberg, 2006).

(4) In Phase IV, two additional energy level diagrams (b) and (c) (Figure 3) were shown to students. Students were asked to explain if one, both, or none of the diagrams represented the Flame Tests that they executed in Phase II of the interview. This phase’s goal was to elicit misconceptions and any cognitive dissonance (Linenberger & Bretz, 2012) related to the connections between the symbolic-macroscopic representations and symbolic- particulate domains of the concept of atomic emission.

Interview Analysis Two methods were used to analyze student interviews: (1) The Constant Comparative Method (CCM) analysis of all interviews for misconceptions; and (2) The Mode-Node Framework (MNF) analysis comparing how GC and UD students build explanations.

Constant Comparative Method The CCM is an inductive data coding process used for categorizing and comparing qualitative data for analysis purposes (Creswell, 2007). It is usually associated with the methodology of grounded theory, but it is also used with other research (Freeman, 2005). In CCM, a unit of data (i.e. a transcript interview) is analyzed and broken into codes based on emerging themes, which are then organized into categories that reflect a logical

understanding of the codes. Ideally in CCM, each interview is analyzed and systematically compared with a previously collected and analyzed interview data before conducting more interviews. A goal of CCM is to reach theoretical saturation, which occurs when no new categories or new information emerge from subsequent interviews. Purposeful sampling (Creswell 2007) is usually employed for this iterative process to solicit data variations that exhaust all angles of the given topic, and have reached saturation.

Constant comparative method analysis. The interviews were transcribed verbatim using audio and video tape recordings. A sample interview transcript is shown in Appendix L. The interviews were analyzed for misconceptions categories using the CCM. The coding of the data was facilitated using software QSR NVivo8 (QSR, 2012). Appendix M shows a sample coding of a student interview. The purposeful sample used in this study included a diverse range of student expertise: High school, first year, and upper division undergraduate chemistry students with the goal to reach theoretical saturation.

The Mode-Node Framework MNF aims to capture students’ understanding by analyzing the knowledge that students draw upon to generate answers, as well as subsequent shifts in their reasoning during an interview (Sherin, Krakowski, & Lee, 2012). MNF focuses upon this explicit analysis of shifts in interviewees’ thinking as they draw on and recombine various knowledge resources. For example, as a student is explaining how atoms release energy, he might explain that atoms release energy because of exothermic reactions, and then shift to an alternative unrelated explanation that atoms loose or gain electrons in the process of releasing energy. MNF analyzes the shifts in interviewee’s thinking known as conceptual dynamics (Sherin et al., 2012) that occur throughout an interview using three major constructs: (1) Node: MNF assumes that knowledge consists of a large number of elements, each of which is depicted as a Node (Sherin, Lee, & Krakowski, 2007). A Node can represent a simple statement at the macroscopic level such as “it will change color,” or a node can represent a more abstract idea, such as a mental representation of an atom. (2) Mode: a recurring pattern of Nodes that is activated during a particular cognitive task in an interview. Figure 4 depicts two different Modes that a student might have in his/her

working memory. The colored circles represent activated Nodes within the Mode (Sherin et al., 2012), and the connections among activated Nodes are depicted using arrows. Ancillary Nodes are activated nodes, but in isolation and disconnected from other Nodes. Mode 2 includes two ancillary nodes in Figure 4. Note that the same activated Node may participate in more than one Mode, as can be seen by comparing Mode 1 vs. Mode 2. (3) Dynamic Mental Construct (DMC): the interviewee’s explanation or reasoning produced within a Mode. It can be short-lived, or context-specific, or even stable, throughout the entire interview.

Figure 4. Representation of two different Modes, showing both connections amongst Nodes and ancillary (isolated) Nodes. (Revised and adapted from (B. L. Sherin et al., 2007).

Mode Node Framework Analysis. The interviews were transcribed verbatim using audio and video tape recordings. A sample interview transcript is shown in Appendix L. Each student interview was analyzed for Nodes and Modes using MNF framework. The nodes’ organization was facilitated using software QSR NVivo8 (QSR, 2012). A sample of Nodes and Modes that captures how a student, Samuel, build explanations about atomic emission during Phase I is shown in Appendix N. A sample of Nodes and Modes that captured how a student, Lucy, build explanations about the behavior of atoms in flame tests during Phase II is shown in Appendix O.

Quantitative Data Collection and Analysis

Concept Inventory Design The misconceptions found during the qualitative analysis of student interviews were used to create the questions and respective distractors in the form of multiple choice items. At this point in the research, qualitative analyses of student interviews merge to become part of a quantitative tool, a concept inventory. The goal of creating the flame test concept inventory (FTCI) was to test if the misconceptions found in 52 student interviews could be generalized to a broader population.

Writing Items The items for the FTCI came from the analysis of student interviews. Some items asked about the connections between the macroscopic, particulate, and symbolic levels of Johnstone’s Domains (i.e. Item 9. “A student drew this model of an atom to represent the flame test. Which arrows best represent what happens to the electrons in the flame test?”). Other items asked about the process of absorption and/or emission of energy (i.e. Item 5. “In the flame test of CuCl2, what must happen to the compound before it can release energy?”). A sample of how an item was written including the stem of an item and distractors with accompanying students’ quotes are found in Appendix P. Validity The next step in the design of the concept inventory was to evaluate its validity. Validity is defined as the extent to which any instrument measures what it is intended to and then to give evidence of that measurement (Carmines & Zeller, 1979). In this study the goal was to measure student understanding of atomic emission for HS Chem, AP Chem, GC and UD chemistry populations.

Expert Alpha FTCI Content Validity An invitation to participate in the content validation of the Expert Alpha FTCI was send electronically to twelve faculty members at the researcher’s institution. The Inventory Expert Validation Informed Consent Form is shown in Appendix Q. The Expert Alpha FTCI was a paper-and-pencil inventory with 18 multiple choice questions (Appendix R). Content validity

depends on the extent to which a measurement reflects a specific domain of content and if it is an adequate sample of the domain of content (Carmines & Zeller, 1979). In this study, Expert Alpha FTCI (the Alpha FTCI version given to experts) was content validated with seven faculty members who had several years of experience teaching general chemistry courses and/or held a doctorate in the field of Analytical Chemistry. They were asked to answer the three questions below: 1) Which question(s), if any, do you find confusing? Why? 2) Which question(s) best represent atomic emission? Why? 3) Which topic(s) were omitted that you feel need to be included to best represent atomic emission? Why? Experts’ responses are discussed in Chapter 5. After content validation of the Expert FTCI, two items were added to the inventory. The twenty-item FTCI was called Alpha FTCI (Appendix S).

Alpha FTCI Participant Recruitment GC and UD instructors signed a consent letter previous to administering the Alpha FTCI in their classes. This letter also allowed the researcher to recruit students for validation interviews. A sample of an instructor’s signed permission is found in Appendix U. Students took Alpha FTCI (Appendix S) after they had been introduced and assessed on the topic of atomic emission. The researcher administered the FTCI in GC and UD classes during fall 2011 semester. Four hundred thirty seven GC students and fifty two UD students from analytical chemistry and instrumental analysis classes took the Alpha FTCI. Two hundred twenty-two GC students and 40 UD students answered all 20 items and consented to have their results use in this study.

Alpha FTCI Student Validation Interviews Validation interviews served to identify problems or ambiguities in the content clarity of items that might lead to the loss of comprehension for students (Leighton, Heffernan, Cor, Gokiert, & Cui, 2011). Student validation interviews were conducted three weeks after the written administration of the Alpha FTCI. This waiting period was chosen because research has

shown that explicit memory does not affect responses in a test-retest situation if they are obtained at or any time after a three-week interval (McKelvie, 1992). The validation interviews followed a think-aloud protocol (Appendix U) in which students answered all 20 items of Alpha FTCI. A think-aloud protocol requires the participant to read questions and say aloud everything going through his/her mind as they respond to the item. This protocol in itself causes an interaction, even if slight, between the interviewee and the interviewer. This type of protocol may encourage respondents to read words and phrases that they may have passed over more quickly or perhaps skipped altogether if left to read silently at their own pace (Presser, 2004). In this study, the purpose of validation interviews was not to look for how consistently the student responded to both administrations, but rather to see if the student understood the intention of the question in the same manner that it was intended by the researcher. Students were asked to read the stem item out loud and to provide an answer of their own. Then the answer choices were uncovered and the student read the choices provided either out loud or in silence, they proceeded to choose an answer. Students were also asked to inform the researcher if they have trouble understanding a question or an answer choice. The interview analyses also provided information about which strategies (elimination, guessing, etc.) students used to choose an answer. After the analysis, some items were modified or eliminated; the discussion of these items is addressed in Chapter 5.

Alpha FTCI Concurrent Validity Concurrent validity is a measure of whether a test is able to successfully distinguish between populations with different expertise (Trochim, 2006). A t-test was used to examine any significant difference between the means of the GC and UD scores (Chapter 5).

Alpha FTCI Scoring A 20-multiple choice item inventory named Alpha FTCI (Appendix S) was piloted at a post-secondary institution in the fall 2011 semester with five different GC classes and two different UD classes at the same post-secondary school where the interviews were conducted. Twenty-five UD students from Analytical Chemistry, 19 UD students from Instrumental Analysis and 222 GC students took the Alpha FTCI. This version had a maximum score of 20

points. All students took the inventory after they were formally assessed on the topic of atomic emission by their respective instructors during the semester.

FTCI Participant Recruitment Student recruitment started with an invitation directed to both high school and undergraduate instructors. Appendix V shows the invitation sent to GC, AP Chem, and HS Chem instructors. Table 3 shows the demographics of the schools where recruitment took place.

Table 3. HS Chem, AP Chem, and GC participant information. HS Chem AP Chem GC U.S. State OH (4), MI (3) , OH (2), NY, NJ, OH NY, WI, IN MI, CO School location 4 urban 2 urban Suburban 6 suburban 4 suburban Type of school 5 public 5 public Public 5 private 1 private # of classrooms 10 6 6 Instructors’ Min=1 year Min=1 year years of Max=21 years Max=33 years experience Mean=11 years Mean=19 years

FTCI Participants High school Participants Nine hundred and forty-four high school chemistry students from 15 schools across the U.S took the final version of the inventory, the FTCI (Appendix W), during spring 2012 semester. Three hundred and eight HS Chem students and 151 AP chemistry students gave permission to have their responses used for research and were included in this study.

Undergraduate Participants Four hundred fourteen students took the FTCI during spring and fall 2012 semesters. Only 362 students consented to have their results used for research and completely responded to all 19 items in the FTCI.

Test-retest participants One-hundred first semester GC students (52% male, 84% Caucasian) took the first administration of FTCI during spring 2012 semester. The academic majors most represented in this test-retest population were 25% engineering, 18% kinesiology, 14% zoology and 13% chemistry majors. A second administration of FTCI was conducted exactly three weeks later in the same classroom. Exactly 80 students took both the first and second administrations of the FTCI and were included in the test-retest sample.

FTCI Student Validation Interviews Three weeks after the first administration of FTCI, three GC student validation interviews were conducted. The analysis of interviews did not reveal any student uncertainty about the items in the inventory, therefore no further changes were deemed necessary. These three interviewees were excluded from the test-retest score analysis.

FTCI Scoring The FTCI has 19 items, which included four 2-tier items. Therefore the scoring of the FTCI was done both as a 1-tier FTCI with 19 items and a 2-tier FTCI with 15 items. In the scoring of 1-tier FTCI, ‘0’ and ‘1’ was assigned when the item was correct or incorrect, therefore it could have a maximum score of 19 points. In the scoring of 2-tier FTCI ‘1’ was assigned when both responses were correct, and ‘0’ when either or both items were incorrect. Therefore the 2- tier FTCI had a maximum score of 15 points. Excel 2010 was used to generate templates and SPSS version 18 (SPSS, 2012) was used for statistical tests. The analysis of the overall test and items was done using Classical Test Theory. This method assumes that every element has a true score and some random error and it is symbolized by: X= t + e, (where X represents the observed score, t is the true score, and e is the random error). This equation suggests that every observed score on any measuring instrument is made up of two quantities: the true score that would be

obtained if there were no errors of measurement, and a certain amount of random error (Carmines & Zeller, 1979). This error assumption gives rise to statistical analyses to inform the researcher about the reliability and discrimination of the measure, i.e., the concept inventory (Ding & Beichner, 2009).

FTCI Item Analysis Item analysis involved three calculations: item difficulty level (ρ), discrimination index

(D) and point biserial coefficient (ρbis).

Item Difficulty Item difficulty (p) is defined as the proportion of students answering that item correctly.

The value of p for each item was measure by the equation: ρ = Nc /N (where Nc is the number of correct responses, and N is the total number of students taking the test. Hence, a high value of ρ actually means an item was relatively easy, while a low value of p means the item was more difficult. The acceptable values of p are between 0.30<ρ<0.80 (Ding & Beichner, 2009). A high value of ρ (ρ>0.8) may indicate that the item was too easy for the test’s intended population and may not be appropriate for inclusion in an inventory designed to elicit student misconceptions. A low value of ρ does not necessarily indicate a malfunctioning item. Rather, a good item can be answered incorrectly by a majority of students because it actually addresses a deep-rooted misconception.

Item Discrimination The discrimination index (D) measures how well an item differentiates between students who score relatively high or low on the entire inventory (Crocker & Algina, 1986). The top and bottom 27 % of student scores were used to measure item discrimination (Cureton, 1957). D

value for each item was measured using the equation: D= Nt − Nb / 0.27N (Where Nt and Nb are the numbers of correct responses in the top 27% and bottom 27%, respectively, and N is the total number of students). Discrimination index values of D>0.3 are considered ideal (Ding & Beichner, 2009). A low item discrimination index indicates that an item is either too difficult because both the top

and bottom students find it difficult, or too easy because both the top and bottom students find it relatively easy.

Point Biserial

Point biserial (ρbis) is a measure of individual item reliability and represents the correlation between the item score (correct=‘1’or incorrect=‘0’) and the overall test score. A satisfactory ρbis value is greater or equal to 0.2 (Ding & Beichner, 2009). The ρbis value for each

item was computed using the equation: ρbis = X1 - X0 / σx SQR (p (1- p)) (Where, X1 is the average

total score for those who correctly answer an item, X0 is the average total score for those who incorrectly answer the item, σx is the standard deviation of total scores, and p is the difficulty index for the item in question).

FTCI Test Discrimination The discriminatory power of the entire inventory was measured by Ferguson’s delta (δ). Ferguson sustained that if the test’s goal is to serve as an instrument that allows the observation of difference in abilities between testers, then measuring the discriminatory power of the 2 2 instrument is necessary (Ferguson, 1949). δ value was computed using the equation: N - ∑ fi / N2 – N2 / (K +1) Where, N is the total number of students taking the test, K the number of test

items, and fi is the number of students whose total score is i. δ values of 0.9 or greater indicates that there is a broad score distribution and good discrimination among all students (Ding & Beichner, 2009).

FTCI Test Reliability Reliability refers to the consistency or repeatability of a measure. In this study, two types of reliability were measured: Internal consistency and test-retest reliability.

Internal Consistency Internal consistency is an estimation of correlation among items and the number of items in the assessment (Nunnally, 1967). It is measured by Cronbach alpha (α), and α values of 0.7 or greater are considered acceptable and thus indicate that all items closely measure the same construct (Cronbach, 1951). Although it is common to present internal consistency coefficients

in the literature for an assessment, it may not be appropriate for a concept inventory (Adams & Wieman, 2011). A chemistry concept inventory would fail the assumption of unidimensionality required by coefficient alpha because of the nature of chemistry concepts where ideas interconnected (McClary & Bretz, 2012).

Test-Retest Reliability Test-retest reliability is obtained by giving the same test to the same people at two distinct points in time. The correlation or stability coefficient can then be obtained between scores on the two administrations of the same test. The assumption is that the responses to the test will correlate across time because they reflect the same true variable. This type of reliability has some limitations in terms of its interpretation. For example if the correlation between scores is low, it may be because the understanding of the target concept(s) has changed. The longer the time interval between administrations, the more likely the concept has changed, because it might be relearn in class. Another limitation is referred as the ‘reactivity’ problem due to the fact that sometimes the very process of measuring a phenomenon twice can induce change in the phenomena itself (Carmines & Zeller, 1979). In this study, the second administration was given within a 3-week interval. It has been demonstrated that in a 3-week interval explicit memory does not affect responses in a test-retest situation (McKelvie, 1992).

CHAPTER 4: STUDENTS’ REASONING PATTERNS AND MISCONCEPTIONS ABOUT ATOMIC EMISSION

This chapter contains the qualitative findings subdivided in two parts. In part one, reasoning patterns were analyzed using the Mode-Node Framework (Sherin et al., 2012) with first-year and upper division undergraduate chemistry students. Specifically, this analysis sought to answer the following research questions: • What reasoning patterns developed in students’ explanations of atomic emission during open-ended questions? • What reasoning patterns developed in students’ explanations of atomic emission in the context of explaining flame test phenomena? In part two, the interviews were analyzed once again, this time using the Constant Comparative Method (Creswell, 2007), in order to answer the question: • What student misconceptions exist about atomic emission?

Mode Node Framework Analysis An example of Mode Node Framework (MNF) analysis focusing on Nodes and Modes was provided in Appendix N. This analysis corresponds to Phase I of the interview with Samuel, a general chemistry (GC) student. Below, the explanation of the Modes found in Samuel’s analysis, and his Dynamic Mental Constructs (DMCs) summarized in Table 14.

Example MNF analysis #1 (Samuel, GC, Phase I). During the interview, Samuel mentioned exothermic and endothermic reactions to explain atomic emission (Mode A). He then created (Mode B) a staircase drawing (Appendix N), explaining that “step 1” was a “big drop” (in energy) going from the n=2 to n=1 energy levels and that energy increased as “you go up the levels.” Samuel then proceeded to mention a list of ideas that might be relevant, without fitting them together (Mode C). This is known as a skimming mode. Mode C included Samuel explaining how electrons go up in energy levels to increase stability by obtaining a noble gas configuration, full octet, or full orbitals. Lastly, Mode D was prompted by a question from the interviewer. As Samuel created a second drawing (Appendix N), he explained graphically how energy decreased in energy state 1. No other

32 student produced a similar representation. Samuel is a student who skimmed through a few Modes, then chose which ones to focus upon. Other GC students with a mode similar to Samuel’s Mode A added the idea of enthalpy changes. Table 4 summarizes Samuel’s Modes, conceptual dynamics (Dynamics) and the Dynamic mental constructs (DMCs) he used in his explanations.

Table 4. Dynamic Mental Construct analysis of Phase I open-ended questions for Samuel (GC). Nodes within Mode Dynamics Current DMC

• Atoms release energy in two Skimming mode: Student Endothermic and brought up two related concepts, exothermic ways

A • Energy is absorbed in an then focused on one, namely an reactions concepts endothermic reaction exothermic reaction, for the were used to release of energy. explain atoms Mode • Energy is released in an exothermic reaction releasing energy.

• Drawing Node: Energy levels Shifting mode: Shift among Student drew a as staircase (Appendix N) active nodes, leading to a change staircase diagram to st in DMC. Other nodes were show the difference • Large energy gap between 1 B & 2nd energy levels, in activated when interviewer in energy gaps st comparison to other levels asked for a representation of between the 1 and nd

Mode atomic release of energy. 2 levels, in comparison to the other steps/levels.

• Atoms move towards stability Skimming mode: Student Atoms tend towards

• Atoms move towards noble gas considering ideas related to how stable states (noble C configuration atoms obtain stability gas configuration, • Atoms want full octets full octets, full Mode • Atoms want full orbitals orbitals).

• Drawing Node: First energy Shifting mode: When First energy level level represented by log interviewer probed for additional can be represented function graph (Appendix N) features such as electron in a graph where

D • Gap between energy levels transitions or energy gaps energy dampens decreased going up levels. between levels, student used log with time. • function graph to represent the Mode Used term ‘Atomic emission’ first energy level, with energy decreasing as electrons return to a stable state

Drawing Nodes. In order to identify the Nodes, Modes, and DMCs for each student, their drawings were coded as Drawing Nodes and grouped accordingly to shared components (Table 5). For example, ‘Bohr atomic models’ all had a center for a nucleus, circles/ellipses as shells or orbitals, and electrons. Table 5 depicts common, representative Drawing Nodes and the number of students who created a version of each. Twelve (100%) UD students and seven (50%) GC students created drawings to show the release of energy by atoms during Phase I of the interviews.

Table 5. Common drawing nodes (with representative examples) in Phase I. Category GC students (N=14) UD students (N=12) (A) N=2 N=8 Energy Level Diagrams (ground state, energy levels and arrows/electrons)

(B) N=1 N=3 Orbital/Bohr atomic models (nucleus, orbitals, shells, electrons)

(D) N=2 N=0 Chemical Reactions

(E) N=2 N=0 Particulate representations

An example of Mode Node Framework (MNF) analysis focusing on Nodes and Modes was provided in Appendix O. This analysis corresponds to Phase II of the interview with Lucy, an upper division (UD) chemistry student. Below, the explanation of the Modes found in Lucy’s analysis, and her Dynamic Mental Constructs (DMCs) summarized in Table 6.

Example MNF analysis #2 (Lucy, UD, Phase II) The second example came from phase II of an interview with Lucy, an upper division (UD) chemistry student (Appendix O). Again, the Modes found in Lucy’s analysis are explained below, and her DMCs are summarized in Table 6. In Mode A, Lucy focused on the salt and the wooden stick, describing how the salt separated into individual atoms in the flame. This last Node included a shift to particulate features as individual atoms were excited in the flame to cause a color change. In Mode B, Lucy mentioned that the metal atoms caused the change in color. Then she focused her attention upon electrons in the d orbitals of copper atoms, recognizing that chloride does not have d orbitals. In Mode C, Lucy made a prediction about the atoms of sodium chloride in the flame test. She used the Node that metal atoms cause changes in the color of the flame. (This is an example of how Nodes are reused in different Modes) Then Lucy added a new Node to Mode C, attributing the flame color to differences in atomic size. Mode D appeared in response to the interviewer’s question. Lucy skimmed through some Nodes: the Bunsen burner flame is blue, sodium chloride produces an orange flame, and metal atoms are responsible for the change in color of the flame. In Mode E, Lucy created atomic models of sodium and copper to represent differences in their atomic radii (appendix O). Lucy used a Bohr atomic model with three specific components: a nucleus, circles or orbits for energy levels, and electrons. Lucy’s Bohr atomic model included arrows to represent the movements of electrons from ground to excited states. Table 6 summarizes Lucy’s Modes with their associated Nodes, conceptual dynamics and DMCs. Repeating nodes are included, providing confirmation that these ideas were prevalent in her DMCs. Note that many of Lucy’s DMCs, in the completed analysis of Phase II, were similar because she explained all three flame tests in a similar manner.

Table 6. Dynamic Mental Construct analysis of Phase II flame test questions for Lucy (UD). Nodes within Mode Dynamics DMC • Compound dissolved in water Skimming mode: Multiple nodes Dehydrated salt • Water evaporates in flame related to visible features while breaks into atoms in

• Salt separates into individual conducting the flame test. flame. Atoms atoms in the flame Shifting node: particulate feature moved into excited appeared as individual excited states. Mode A • Individual excited atoms move into excited states atoms moved into excited states.

• Individual metal atoms are Shifting mode: Flame color Electrons in metal d responsible for the change in caused by the copper metal orbitals get excited color of the flame atoms, specifically by the in the flame, • Metal (copper) atoms have d electrons in d orbitals. producing a change Mode B orbitals, but chloride does not in flame color.

• Metal atoms were responsible Interviewer asked for prediction. Amount of energy for the change in color of the Student applied previous nodes released (color of

flame of sodium chloride from Mode B that the metal flame) due to ionic/ • Different ionic/atomic radii caused the flame color. atomic radii. cause different color flames Shifting mode: Difference in

Mode C atomic radii caused difference in flame colors.

• Bunsen burner flame is blue Interviewer probed observations. Observation of

• Sodium chloride produces an Student noticed blue flame of ‘blue’ Bunsen orange flame Bunsen burner, then returned to burner flame. • Metal atoms/ions are metals as causing the change in Recurrent mode

Mode D responsible for the change in flame color. explains the change color of the flame in flame color is due to metal atoms. • Sodium atom is smaller than Interviewer driven mode, student Energy gap related copper atom moved through the Bohr models, to energy release. • Drawing Node: Bohr models this caused the emergence of a Differences in of copper and sodium atoms fledging mode, excited electrons energy gap depend

• Electrons move up to excited relaxed back to ground state. on different atomic states Energy gap corresponds to the radii. • Different ionic/atomic radii atomic/ionic radii. Mode E cause different color flames • Energy gap corresponds to atomic/ionic radii • Excited electrons relax back to ground state

Reasoning Patterns about Atomic Emission in Open-Ended Questions The open-ended questions in Phase I generated a wide variety of responses. Student Mode analysis lead to the identification of DMCs. On average, general chemistry (GC) students used three DMCs while upper division (UD) students averaged five. These averages were calculated by tallying each student’s DMCs and adding them up and divided by the total number of either GC or UD students who participated. The minimum number of DMCs for GC students was one and the maximum number was five, in the other hand the minimum number of DMCs for UD students was two and seven was the maximum number. The most common DMCs are presented in Table 7 for both GC and UD students.

Table 7. Dynamic Mental Constructs (DMC) about atomic emission. DMCs in Phase I GC UD 1. Atoms release energy in the form of heat 10 6 2. Endothermic and exothermic reactions explain how atoms release energy 7 1 3. Atoms release energy in the form light/radiation/photon 6 10 4. Mixing atoms/compounds/molecules/ions produces a reaction. If the reaction 4 1 causes bond breakage/forming, then energy will be released 5. Atoms moving/speeding/vibrating/colliding to release energy 3 0 6. Atoms release energy when they change state, e.g. evaporation, melting 2 0 7. Atoms release energy by filling orbitals/shells to obtain an octet to become 2 1 stable 8. Electrons in higher energy orbitals return to ground state to release energy 1 6 9. Electrons move up to excited states in a quantized manner 1 4 10. Electrons move to higher energy orbitals causing electrons to be lost/gained, 1 2 hence the release of energy 11. Electrons must absorb energy to be promoted into excited states 0 8 12. Excited electrons return to ground state because of more stability 0 6 13. Energy gap between excited and ground states corresponds to amount of energy 0 5 released 14. Bonds forming/formation of ionic compounds causes release of energy 0 2 15. Fluorescence/phosphorescence is a form of atomic release of energy 0 2

Atoms release energy in the form of heat and light/radiation/photon The ideas that atoms release energy in the form of heat and light (DMCs 1 and 3) were commonly used by both GC and UD students.

Exothermic reactions are used to explain how atoms release energy Exothermic reactions as atomic release of energy was a prevalent DMC for GC students and typically was the first to arise during the interviews. Consider Samuel (GC) who responded to the first question about how atoms release energy with a drawing found in category (C) Enthalpy in Appendix N where he noted that a reaction with a negative change in enthalpy (∆H) represented atoms releasing energy:

“if you are given a balanced equation and you have Delta H that was a negative number that would imply that it was an exothermic reaction and so you can tell that heat was giving to the surrounding, whether there was a chemical reaction or whether it was added to element A and B.” (Michael, GC)

Mixing substances (atoms/compounds/molecules/ions) produces a reaction. If the reaction causes bond breakage (or bond forming), then atoms will release energy When students were asked to explain how atoms release energy, in the absence of any particular context, they spontaneously evoked a framework of bonds breaking (and/or forming) to release energy. This was particularly common for GC students. Consider these representative examples of both bond breakage and bond forming being invoked to explain how atoms release energy:

Breaking bonds releases energy. Kat (GC) explained that atoms released energy when bonds between atoms were broken: I don’t really know that much about it actually. I do know that atoms do release energy when they are moving or whenever bonds break. Other than that I don’t really have a lot of experience with atomic chemistr. (Kat, GC)

Only one UD student evoked this DMC, using enthalpy diagrams (Figure 9) to explain:

When a bond is broken or formed, atoms release energy. (Ringo, UD) Ok, can you represent in a diagram or picture how atoms release energy? (Interviewer) Ummm there is for bond breakness (sic), there is like an initial state and how rate goes, it could be like that (left side of Figure 5). This is going from a less to a more stable state (left side of Figure 9) and this is going from more (stable) to a less stable state (right side of Figure 9)

Figure 5. Enthalpy diagrams to explain energy release in bond breaking (Ringo, UD)

Forming bonds releases energy. Another UD student, Samantha, spoke of the idea that forming a compound released energy, explaining as she drew Figure 6:

…just like Na is plus (+) and Cl is minus (-), when they combined together they became neutral and then they give off energy. (Samantha, UD) Ok, do both give out energy? Or what’s going on? (Interviewer) I would assume they both (ions) give out energy. (Samantha, UD) So the process of coming together, combining releases energy? (Interviewer) Yeah. (Samantha, UD)

Figure 6. Formation of a compound releases energy (Samantha, UD)

Atoms release energy by filling orbitals/shells to obtain an octet in order to become stable The idea that electrons move into higher energy levels to become more stable and to fill octets is shown in Samuel’s quote: Can you draw a representation of an atom releasing energy? (Interviewer, probing for a representation) I think, you would have a staircase type picture (Figure 7) and then one big drop here, this would represent the first level of energy and then you will go up, the energy would be increasing when you are trying to go to the second level of energy because of a… I forgot what it’s called, but it is because of the idea of becoming a noble gas, where you are wanting a full octet or a full energy orbital and later on, goes to the third energy level, fourth energy level and so on, where the energy needed would be decreasing as you are going up the levels of energy. (Samuel, GC)

Figure 7.Energy level diagram as staircase (Samuel, GC)

Electrons move to higher energy orbitals causing electrons to be lost/gained hence the release of energy Three students spoke of the idea that ionization occurs when atoms release energy. For example, Rachel (UD) sustained that when an atom loses an electron, it induces other electrons to return back to lower energy levels thus releasing energy (Figure 8):

This is the nucleus (pointing at the center) and then you have your energy levels up here (pointing at circles). You are going to have the electrons there (dots on circles) and then, this is like ground state (points at circle closest to center), but if one of this, umm if you

get an electron to come out here (pointing at circle farthest away from center) that would be the excited state, but then once you lose this electron (adds an X over one electron), it (the other electron) has to go back down to ground state right there. (Rachel,UD) Where is the release of energy happening? (Interviewer) The release of energy will be happening right here (adds an arrow), when it comes back down to the ground state. (Rachel, UD)

Figure 8. Losing electrons as part of atomic release of energy (Rachel, UD)

Then when asked for an explanation for absorbance of energy to test if the same idea was held in the student’s mind, Rachel’s DMC was explained in reverse:

When does absorbance happen? (Interviewer) Absorbance happens when it (atom) has to attract an electron, whenever an electron just attaches to it, to come into the outer energy levels. (Rachel, UD)

Liz (GC) had the same DMC and explained it by drawing the movement of electrons between orbitals, as well as the losing and gaining of electrons (Figure 9):

They (electrons) will change orbitals. And maybe like sodium. May I (drawing)…Sodium releases 2, 3, 3s1 not 3p1 to 3s1, yeah, it will change the orbitals. (Liz, GC) Can you redraw this one again? Can you explain what you mean by this? (Interviewer) The orbital changes (Liz, GC) How can the orbital change? (Interviewer)

Because I think the sodium will join some compound and then stay in the compound as an ion or cation, so its orbital maybe it’s this (pointing at [Ar]3p1) and then if we treated like a combustion, it changes orbitals (pointing at [Ar]3s1) because it will lose or gain electrons (Liz, GC) So ‘the orbital changes’ happen because it will gain or lose electrons? (Interviewer) Yes, it (atom) will lose or gain electrons, maybe at the same time the energy, the enthalpy will transfer or something (Liz, GC) What’s going to happen to the enthalpy? (Interviewer) The enthalpy, if it is endothermic, the delta H will be positive and the enthalpy will increase (Liz, GC)

Figure 9. Gained/loss of electrons as part of atomic release of energy (Liz, GC)

Liz (GC) utilized two DMCs to explain how atoms release energy: Electron movement between orbitals causes some electrons to be gained or be lost within the atom, and those electrons being lost or gained within an orbital affects the enthalpy of reaction.

Reasoning Patterns about Atomic Emission using the context of a flame test GC students used an average of three DMCs, and UD students averaged four DMCs during the flame tests in Phase II. DMCs are summarized in Table 8. GC and UD students explained the flame tests of copper(II) chloride, lithium chloride and sodium chloride were in a very similar manner.

Table 8. Dynamic Mental Constructs in flame tests. DMCs in Phase II GC UD 1. Color of flame is due to a different cation in the compound, and its location in 6 7 the periodic table 2. Atoms go from solid to liquid to gas, they collide and speed up in the flame 5 0 3. The flame is the source of energy to excite electrons/atoms 4 7 4. The flame causes substances to melt, bonds to break, rearranging and forming 3 1 new compounds or individual atoms 5. Color of flame depends on atoms’ temperature/ kinetic energy/movement 3 0 6. Color of flame is due to the loss or gain of electrons that causes the release of 2 2 energy 7. Compound undergoes an exothermic reaction that causes the release of energy 2 0 8. Flame acts as an indicator, the flame permits to see a change in color for the 2 0 different elements. It is similar to acids and bases indicators 9. Flame acts as a catalyst. The flame starts up that allows the reaction to happen 2 0 quickly 10. Excited electrons move down to more stable states, lower levels releasing 1 10 energy in the form of photons, light 11. Color of flame corresponds to energy gap between excited and ground states. 0 10 This gap correspond to valence electrons electronic transitions 12. Color of flame due to the different orbital energy requirements (s,p,d and f 0 5 orbitals)

Atoms in the flame release energy when they go from solid to liquid to gas, and when they collide and speed up in the flame Some students, such as Ann (GC), described a ‘kinetic theory of particles’ to explain what happens to atoms in the flame test. Even though the interviewer prompted Ann to think about the changes in the color of flame, she did not provide a different DMC. Consider Ann’s generation and subsequent discussion of Figure 10:

So I’m drawing a bunch of circles that are very rigid and aligned (Ann, GC) What does that represent? (Interviewer) The solid form of the compound, the solid, and then it passes to liquid phase too, which I’m not going to draw, but the gas state of it, it will just be a bunch of randomly placed atoms that are kind of free to move around and interact not as rigidly as the solid and that will be the same for all of those compounds. (Ann, GC) Ok, would it be a difference if you see one color, green versus the red, for how these atoms behave? (Interviewer) The atoms as a whole, go through the same change and the particles will act similarly but the speed at which they are moving or I guess the interactions with one another, might change a little bit base on the compound that they are in, so I that’s what I mean. (Ann, GC)

Figure 10. Particulate representation of flame test (Ann, GC)

The flame causes substances to melt and bonds to break to form individual atoms Below is a representative drawing node (Figure 11) and explanation from Matt (GC) after he was asked to explain what happens to lithium chloride in the flame test:

What I have here, I basically do the same thing for all of them (other flame tests), because they are all solids and as you put it (sic) in the flame, they started to disorganize, every atom (sic). Even, mmm because they all have different colors I feel that something different is what determines the color of the flame. The flame disintegrates every single atom, they separate. Like I drew here, the solid have them (atoms) all together but the flame pulls them apart from each other. (Matt, GC)

Figure 11. Particulate representation of the flame test (Matt, GC).

Another student, Michael (GC), invoked this DMC using an equation (Figure 16):

The copper chloride plus the heat yield the copper solid and the chlorine will go away. The chlorine will go away pretty fast and the copper will still burn in the blue/green flame after the copper was gone. And there’ll be 2 moles of chlorine for every copper because the chlorine is -1 and the copper is +2 so you have to have two chlorines to even out the electrons so they bond correctly. And then when you put the heat in, that makes the electrons change err jump to a different orbital and the atoms break apart and the same will happen to the lithium chloride except there is only 1 mole of chlorine because lithium is only +1, which you know from the periodic table. But still the same thing when you put in the heat, the chlorine and lithium will separate and you will have just a lithium solid left on the popsicle stick. (Michael, GC)

Figure 12. CuCl2 in flame test (Michael, GC)

Flame color depends upon atoms’ temperature/ kinetic energy/movement Consider Rose’s (GC) response that describes how the movement of atoms causes the change in color of flame: The different elements that are formed to make the different (salts of) chlorides, make different colors when placed in flame because the atoms not necessarily give off colors but their (atoms) movement give off colors. (Rose, GC)

You said the movement? (Interviewer) I said maybe the movement of the atoms or the release of energy. (Rose, GC)

Flame color due to the loss or gain of electrons, causing the release of energy As in Phase I, the idea that ionization happens during atomic release of energy again appeared again as a DMC in explaining the flame tests. Like her earlier drawing node (Figure 13), Rachel (UD) drew a similar representation to explain Phase II (Figure 8): Yeah, it’s a horrible drawing (Figure 13) but, because lithium when it loses its electron, it becomes excited, it’s only going to have this energy level to fall back upon, then when sodium, when it loses its electron when it becomes excited, it already has two complete full energy levels to fall back upon, so the sodium atom is still going to have more energy since it has more of full electron orbitals. (Rachel, UD) Would you please draw a diagram representing an atom gaining energy? (Interviewer) Alright, (drawing Figure 13) gaining energy, I think it is (atom) going to gain energy when it loses electrons, so can it be the same thing with this sodium here. (Rachel, UD)

Figure 13. Ionization during flame tests (Rachel, UD)

By comparing her explanations in both Phases I and II, Rachel clearly believes the release of energy happens as a consequence of ionization. When asked to clarify her ideas, Rachel provided yet another representation (Figure 14) to depict atomic absorption and release of energy: Can you draw another one (picture)? (Interviewer) Yeah, ok. The nucleus, it’s unstable, I think is going to gain energy when you lose that electron (Figure 14). (Rachel, UD) Can you label that here (pointing at the atomic model on left, Figure 14), so in what case would that happen? (Interviewer)

Kind of like in an instance, if the flame just absorbs a lot of energy this (the electron with arrow on left atomic model, Figure 14) is going to leave. (Rachel, UD) Ok, would you please draw a diagram representing an atom releasing or losing energy? (Interviewer) Sure (right atomic model, Figure 14). (Rachel, UD)

Figure 14. Atomic absorption and release of energy, (Rachel, GC)

Comparing GC and UD students in Phase I During Phase I, GC students most commonly explained how atoms release energy in terms of : (1) exothermic reactions; (2) bond breakage; (3) atoms moving; (4) atoms changing their state of matter; and (5) their tendency to achieve an octet and gain stability (DMCs 2, 4- 7 in Table 17). These explanations were used more frequently by GC students than UD students. DMCs 5 and 6 (atoms moving and changing states of matter) were exclusively used by these students; in other words, no UD students used these DMCs to explain how atoms release energy. UD students in Phase I described how atoms release energy mostly in terms of (1) excited electrons returning back to the ground state; (2) electrons getting excited in a quantized manner; (3) ionization; (4) a required absorbance step; (5) excited electrons returning to ground state to achieve atomic stability; (6) the energy gap between excited and ground states corresponding to the amount of energy released; (7) bond breakage in ionic compounds; and (8) fluorescence or phosphorescence (DMCs 8-15 in Table 17). These explanations were used more frequently by UD students than GC students. DMCs 11-15 (a required absorbance step, excited electrons returning to ground state to achieve atomic stability, the energy gap between excited and ground states corresponding to the amount of energy released, bond breakage in ionic compounds, fluorescence and phosphorescence) were exclusively used by UD students. In other words, no GC students used these DMCs to explain how atoms release energy. The ideas that atoms release

energy in the form of heat and light (DMCs 1 and 3) were commonly used by both student samples.

Comparing GC and UD students in Phase II During Phase II, GC students described what happened to atoms in the flame tests using explanations such as (1) atoms changing their state of matter; (2) bonds breaking; (3) atoms’ temperature/movement determining the color of flame; (4) exothermic reactions; (5) flame as an indicator and as a catalyst for a reaction (DMCs 2, 4, 5, 7-9 in Table 18). These explanations were used more frequently by GC students than UD students. DMCs 5, 7-9 (atoms’ temperature determining the color of flame, exothermic reactions, flame as an indicator and as a catalyst for reaction) were exclusively used by GC students. In other words, no UD student used these DMCs to explain the flame test. UD students described what happens to atoms in the flame test as (1) excited electrons moving down to lower energy levels; (2) the energy gap between excited and ground state corresponding to the color of flame; and (3) color of flame caused by different orbitals energy requirements (DMCs 10- 12 in Table 6). These explanations were used more frequently by UD students than GC students. DMCs 11 and 12 (energy gap between excited and ground state corresponding to the color of flame, and color of flame caused by different orbitals energy requirements) were exclusively used by UD students. In other words, no GC student used these DMCs to explain the flame test. Ideas such as the color of flame being due to the different cations, the flame as the source of energy to excite electrons, and the color of flame being due to ionization (DMC’s 1, 3 and 6) were appealing for both groups of students during Phase II.

Misconceptions of Atomic Emission

Misrepresentations of atomic emission Symbols and conventions. During Phase III of the interview, students were given the energy diagram in Figure 15. Phase III explored the students’ understanding of the symbolic domain.

Figure 15. Energy level diagram used in Phase III. Adapted from Chemistry: The Molecular Nature of Matter and Change, page 257(Silberberg, 2006).

Students were asked to explain their understanding of the conventions and symbols found in Figure 15. They were told that ‘In chemistry we use different types of diagrams to represent what is going on in the atomic level, please take a look at this diagram (Figure 15), and I am going to ask you questions about it’.

When students were asked, what does this zero energy mean? The following were representative student responses:

Luke, an AP Chem student, thought that zero energy was the ground state, ‘the ground state, it is the most stable state, it is not excited. The atom is in its ground state, the most stable.

Samuel, a GC student, thought that zero energy represented the stability of an atom, ‘the atom is in a stable state’.

Arthur, an AP Chem student, expressed this stability as, ‘zero, it is kind of like helium or neon, or argon, something that is very stable something that it is unlikely to gain or lose energy, by creating bonds with others atoms.’

Students also related zero energy to either, no energy per atom is needed to get there. (Rose, GC) or that the energy level has no energy, ‘it (Zero energy) means that there is not energy in that energy level, that the atom is neutral possibly. (Jewel, HS Chem)

Only HS Chem students explained zero energy as related to the lack of atomic movement:

It either means that all of the atoms had come to a complete stopped or like the atom doesn’t have any more potential or kinetic energy. (Alex, HS Chem)

It means that no energy exist at that level and that atoms are solid, not moving, they are just solid I guess. (Meredith, HS Chem)

When students were asked, what does the n mean? The following are representative student responses: Some students thought that ‘n’ meant the number of atoms, electrons or particles.

n is corresponding to the number of electrons, I think n is the number of electrons, is either that or energy sublevels. (Rachel, UD)

The n value is like the number of electrons in the atoms. (Samantha. UD)

The number of atoms or particles. (Alice, GC)

Some students thought that ‘n’ meant the orbitals. n is the orbital in which the electron is sitting in. (Alyssa, GC) The n means that orbital that the electron is in. (Darren, HS Chem)

Some students used similar definitions for ‘n’ that are also used in chemistry,

Moles, because that’s how we used to represent moles in class. (Elizabeth, HS Chem)

I remember that when we are doing equations that n stood for mass, I’m not sure that makes sense in this situation. (Alex, HS Chem)

When students were asked, what do the numbers next to the energy axis mean? Some students explained that it represents that energy release from an exothermic reaction:

It gives the person the amount of energy being release and the negative numbers is going back to the exothermic energy being release. (Samuel, GC)

Jewel, a HS Chem student, related the negative numbers on the energy axis to the electrons in the atom. It means that the atoms have more electrons in the atom than positive particles. (Jewel, HS Chem)

During Phase IV of the interview, students’ were given the energy level diagrams (Figure 16) and asked: Would either or both of these diagrams be connected to the flame test you just did? The intent of Phase IV was to elicit conceptions related to connections between the symbolic and the macroscopic domains.

Figure 16. Energy level diagrams used in Phase IV

Table 9 shows a tally of students’ choices. Not everyone who chose both diagrams (Figure 16) was able to offer a scientifically correct explanation.

Table 9. Students’ choice of energy level diagram(s) Diagram ↑ ↓ Both ( ↑↓) Neither Total HS Chem 3 2 5 2 12 AP Chem 0 0 12 2 14 GC 4 2 5 3 14 UD 1 1 10 0 12 Total 8 5 32 7 52

Students who chose only the “up-arrow” energy level diagram. Darren, a HS Chem student, thought the “up-arrow” diagram best represented the flame test because he believed that the atoms were increasing in energy and generating more energy. When Darren was asked about the down-arrow diagram, he thought that it represented atoms that got colder or that were taken out of the flame, and as such, the diagram does not represent the flame test:

I think this one (up-arrow diagram) will represent the flame test and this one (down-arrow diagram) will represent if they got cold…..They are related because flame heats up the atom which produces more energy, so it would have the increase of energy, without having to lose any. (Darren, HS Chem)

Kat, a GC student, also chose the up- arrow diagram because there was an overall increase in energy in the atoms. This increase in energy was ‘expressed’ by the visible color flame she observed which indicates a release of energy:

I think this one (up-arrow diagram) will be related, because it’s like expressing a release of energy since the atoms were really seeing energy in the form of light it would more than likely have an arrow pointing up in this diagram. (Kat, GC)

Another GC student, Liz, also chose this diagram because she focused on the energy created by the combustion of the gas that produced the flame. She thought that the atoms in the compounds were absorbing the energy released by the flame.

Because if you combusted the methane (in the Bunsen burner), you will give energy to the atoms. The atoms will gain energy and so they will go to the upper level….This arrow means it wants energy to form and the flame provides that energy. (Liz, GC)

Samantha, a UD student, also focused on the flame of the Bunsen burner as a source of energy. She explained that as the elements in the compound were heated, their energy increased:

the flame is giving off heat, which is heating the elements which is giving off energy, so I would assume the energy would increase, so that’s why I picked this one. (Samantha, UD)

Michael, a GC student, chose the up-arrow diagram because he focused on multiple inputs of energy necessary to break apart the compound, in this case copper(II) chloride. Michael was prompted to redraw the diagram so he could add features contained in his explanation. (Figure 17):

The arrow going from one to fourth (up-arrow diagram) I ‘m not really sure what the product or the reactants will be like but like one would be copper chloride and then arrow shows you how much, you can say that you added heat and then the fourth reaction that will give you the products, say this is

reaction 1 will say like CuCl and then number fourth will have a copper plus chlorine and it will show the energy trying to break down all the copper and chloride. (Michael, GC)

Figure 17. Flame Test of copper(II) chloride breaks compound apart (Michael, GC)

Students who chose only “down- arrow” energy level diagram. Alex, a HS Chem student, chose the down- arrow diagram because he believed that electrons were lost from the atoms to increase stability, and therefore the energy decreased overall:

In the flame test, the valence electrons on the substances were lost to make them (substances) more stable that’s why the (visible) color of the flame stopped and when back to normal (color) after a while, so this chart (the down-arrow diagram) shows that after a while, after the flame test, it (substance) loses electrons it becomes more stable the energy decreases. (Alex, HS Chem)

Alice, a GC student, chose the down-arrow diagram because she recognized that atoms released energy but they do not absorb energy.

Probably this one (down-arrow) because I don’t think any of the reactions pull energy from the flame, it just used it as a mean of reacting… When they react energy is released into the flame, so the release of energy from the atoms. (Alice, GC)

Students who chose both energy level diagrams. Annie, a HS Chem student thought that the up- arrow diagram represented electrons that are added to the atoms as energy is also being added to atoms. Also, the down-arrow diagram represented the decrease of energy.

In the first, the arrow going up, energy is being added, more electrons are being added and the second one (diagram) energy is being released so the energy is going down. (Annie, HS Chem)

Rachel is another student who thought that both arrows were required. The first arrow depicted the energy and the electrons gained by the atoms; the second arrow was there to represent the atoms returning back to ground state, and the released of electrons.

The flame test is going to be a source of energy so when they (atoms) are in the flame they are going to get excited but after they are excited they are going to have to come back down to the ground state and they are going to lose the electrons that they gained and they are going to release those and then return. (Rachel, UD)

Billy, a GC student, believed both diagrams were needed to represent the flame test. He focused on the action of putting the compound into the flame representing the up-arrow diagram, and taking the compound out the flame, representing the down-arrow diagram.

This one (up-arrow diagram) will represent when an atom was heated and this one (down-arrow) will represent the atom was taken out of the flame. (Billy, GC)

Matt chose both diagrams in order to represent what gains and what loses energy. In his explanation, the salt gained energy, and the flame lost energy by giving energy to the salt:

… I feel that the salt gained some sort of energy which made it change the state of it, not necessarily the state of it but maybe the color and atoms have to gain some energy to disintegrate and stuff like that… The flame will be this right here (down-arrow diagram) and the salt will gained energy here (up- arrow diagram) (Matt, GC)

Regina, a GC student, chose both diagrams and assigned the diagrams to different compounds according to which compound was absorbing or releasing energy. In the case of lithium and sodium salts, the up-arrow diagram would be appropriate to represent these compounds because these compounds absorbed energy. In the case of copper(II) chloride, down-arrow diagram represented this compound because it released energy.

Since I based it off from energy being release or absorbed, then I would say that, with like the copper chloride then that is going to be releasing more energy and so it is going to be in a lower energy level (down-arrow diagram), the other two will be higher… I think this one (up-arrow diagram) will represent the other two (lithium chloride and sodium chloride) because is going up. (Regina, GC)

Regina, the same student from above, represented the red flame and green flames produced by lithium and copper(II) chlorides. Again, her choice of arrows, applied to atoms depicted by circles, in Figure 17, reflected her choices of energy level diagrams as explained above.

The red flame is absorbing the energy because, I‘m guessing, because it doesn’t have the energy in it to make everything happen, it is like in the surrounding atoms around it have to make the reaction happened, and then the green flame, the atom in that one, it has the energy and it is actually acting on the reaction so it is doing the work. (Regina, GC)

Figure 18.Color of flames in flame tests of Lithium Chloride and Copper(II) chloride (Regina, GC)

Atomic properties Some students focused on certain atomic properties, such as the availability of atomic orbitals, location in periodic table, ionic radii, ionic charges. Then students related these atomic properties as having an effect on atomic emission or causing atomic emission. These ideas are discussed below.

Excess energy multiple color flames. Olivia, an AP Chem student explained that electrons have a limit of how much energy can be absorbed during a flame test. She attributed seeing only one color per substance instead of multiple colors, because the flame was constant. This student assumed that if we were to add more energy we could get electrons to absorb more energy and release multi-color flames:

If the flame would get hotter, then the (color) flame that is created as the element burns that would change color because the electrons would be changing even more, gaining a lot more energy, so yeah, there is a limit of why we would get multiple colors from one substance. (Olivia, AP Chem)

Location of elements in periodic table. Students were asked to explain the difference in the color of flame of compounds provided. Some students attributed this phenomenon to their close location of Lithium and Sodium in the periodic table, which created similar colors, red and orange. For example:

These two (lithium chloride and sodium chloride) are more similar than the green (copper(II) chloride)… because they (lithium chloride and sodium chloride) did not have the sparks like the green, they were more solid, and not as bright as the green flame; this is because their electron configurations (lithium chloride and sodium chloride) are more similar because they are both period one, so each one, lithium and a chlorine, you basically lumped them together, they are going to have some full inner shells of eight electrons and then in their outer shell there is only an electron and so as that (electron) jump.. it (the jump)is a significant difference from copper which, on the other

hand, copper is going to have, I’m not quite sure how many valence electrons is going to have looking at the formula on the bottles (containers for salts of chloride). (Olivia, AP Chem)

Some students attributed the differences in the color of the flame to the type of metal in the compound:

….they are different, copper is a metal, metalloid? (looking at the periodic table), and this is an earth metal (referring to Lithium), so they burned different. (Eleonor, GC)

Both the white powders were alkaline metals and the green powder was like a transition metal, so I see that has to do with the different colors (of flame) we see. (May, AP Chem)

Another student, Samantha, attributed the differences in the color of the flames to the atomic number of the metal in the compound:

…sodium is lower in the periodic table of elements, even though they are in the same column they are in different rows. I think it is because the difference structures and how sodium has more, a higher number than lithium does. Sodium is 11 so the atomic number is higher than lithium. (Samantha, UD) What does the atomic number has to do with it? What is the effect of the Atomic number, can you explain? (Interviewer) I would say with a higher atomic number it gives off a greater energy than a lower atomic number (Samantha, UD)

Ionic Radii. A HS Chem student, Meredith, sustained that in the salt of chloride, the bigger element in the compound will produce the flame color in the flame test:

What determines the color of the flame that you see in the flame test? (Interviewer) that would be which element in the compound is more prominent or has maybe the more orbitals. (Meredith, HS Chem) can you explain that a bit more? (Interviewer) it would be which atoms are the most complex or the biggest, which has or it is closest to a noble gas maybe, that one will stand out with the color more. (Meredith, HS Chem)

An AP Chem student, Waldo, explained that the larger atoms in copper(II) chloride released more energy in comparison to lithium chloride that contained smaller atoms:

Lithium just has an s orbital, and the copper has a much larger atom, it has the p and d orbitals as well, so I think because those atoms and those electrons are further from the nucleus so when they are broken (sic) they will emit a different wavelength of energy versus the lithium which is much closer to the nucleus, so it gives of a different amounts of energy, different wavelengths. (Waldo, AP Chem)

Even an UD student, Lucy, invoked this idea. She provided a representation that used the reasoning of how ionic sizes might be proportionally related to the length of the arrow that represents atomic emission (Figure 19):

sodium is definitely smaller than copper, um, these are not actually what the shells look like, and so the electrons here, if they go onto an excited state they have less room to relax back down, whereas in copper they can go to a higher state and they have more energy to give off when they relax back, so yeah because the copper electrons have more room, I guess to relax back down to the ground state, so greater energy. (After seeing the other flame tests, gives prediction of what would happen next) the same thing, probably not the same

color change cause the atoms are different size but different color of the flame because of the metal ion. (Lucy, UD)

Figure 19. Atomic radii related to different colored flames (Lucy, UD)

Effective nuclear charge. A student explained that similar color flames of lithium and sodium chloride, red and orange colors, were produced due to same effective nuclear charge present in both lithium and sodium. Even though Olivia did not explain what effective nuclear charge, she related these atomic properties to the colors of flames.

I ‘m not sure if it is more or less energy, but that it is going to account for the (flame) color changed because the energy, see this one is going to be orange (flame) and the other gives you red (flame) because is so much closer to lithium (nucleus) so if you do effective nuclear charge, they both have an effective nuclear charge of one, but since this one (electron) is so much further away (from nucleus), is not exactly the same, that’s why they are close in color, you have the red and the orange as suppose to the green but it is still very different (Olivia, AP Chem)

Number of valence electrons. When students were asked what determined the color of flame, many students attributed the color of the flame to certain reactions that take place during the flame test. Students who thought that the number of valence electrons that were involved in these reactions determined the color of the flame.

This is the copper atom (left diagram, Figure 20), it has a lot more electrons and protons than lithium atom does, this is the lithium atom (right diagram, Figure 20), they have different number of valence electrons too, so when they burned, takes a different amount of electrons to start the reaction and they react different with the flame. (Alex, HS Chem)

Figure 20. Atomic representations of metals from copper(II) chloride and lithium chloride (Alex, HS Chem)

Different inner energy shells affect energy release. Olivia, an AP Chem student, maintained that the differences in the inner shells of the metals caused the release of differing amounts of energy because electrons have to drop into these different inner shells to release energy.

The flame test is going to be the energy release once it goes back to the ground state so that is going to be different for each of these (substances) because of the different energy levels, even though lithium and sodium they both have only one electron in the outer shell, they have different amounts of inner shells so these have different energies that it has to drop and release that energy. (Olivia, AP Chem)

Terminology used out of context When students were asked about the role of the flame in the flame test, their responses mostly indicated that the flame acted as a source of energy but a few students provide unexpected answers, as shown below:

Flame as a catalyst. Annie, a HS Chem student described the flame to be acting as a catalyst. The attribute given to the flame was that it accelerated the reaction, thus acting as a catalyst.

The flame is acting as a catalyst for the reaction to occur, if it is not going to be able to heat, then the reaction, it is going to happen very slowly, so the flame is heating up the elements so they can let off the bright color. (Annie, HS Chem)

Arthur, an AP Chem student, also described the flame as a catalyst, which causes bonds to break:

The role of the flame is almost like a catalyst, it’s what breaks the bond. (Arthur, AP Chem)

Flame as overcoming the activation energy. Arthur, an AP Chem student, described how the flame plays a role in overcoming the activation energy required for the reaction to take place:

….there is something you call activation energy so in something that is losing energy, something that is exothermic like the flame test, you have, you put in energy before you lose it and this area from here to here (pointing at dotted line on Figure 21) represents the energy that you are putting in, in order for the reaction to occur, that can be in the form of a catalyst. (Arthur, AP Chem)

Figure 21. Activation energy overcome by flame (Arthur, AP Chem)

Carmen, an AP Chem student described the flame’s role as the initiator of the reaction, similar to the activation energy needed to break bonds:

The flame acts as, I can’t think of the specific word, but it kind of initiate the reaction, maybe it might be like the activation energy, if you consider the heat, in Joules, of how much it might take to break those bonds, it could be the activation energy in order for the reaction to take place. (Carmen, AP Chem)

Flame as an indicator. Alice, a GC student, explained that the flame acted as an indicator. She pointed out that the flame offered a visual representation of what it is going on at the atomic level.

Besides giving heat for the reaction to take place. It works as an indicator. It changes color for the elements that are on the flame… the flame works as an easy indicator if there is a reaction or not without having to look at the atomic level trying to burn atoms, so you can look up different things in short period of time. (Alice, GC)

Forming/breaking bonds in the flame test releases energy

Forming bonds in the flame. Some students described the formation of bonds by atoms to achieve a noble gas configuration and producing atomic release of energy. A HS Chem student explained that the transition from charge ions to neutral compounds caused this release of energy (Figure 22):

…this is an atom, this is the nucleus, and the outer layer has the valence electrons, say this one (left diagram) has 7 valence electrons, and this one (right diagram) has only one valence electron, so it will bond to the first one and give it its electron, then energy will be released. (Alex, HS Chem)

Figure 22. Formation of ionic compound (Alex, HS Chem)

Likewise, Samantha, a UD student, explained, as she drew Figure 23, that the formation of neutral compounds produced the release of energy.

…just like Na is plus (+) and Cl is minus (-), when they combined together they became neutral and then they give off energy I guess. (Samantha, UD)

Figure 23. Bond formation causes release of energy (Samantha, UD)

‘Atoms achieving a noble gas configuration’ was an appealing idea to explain how atoms exchanged electrons:

Atoms can either shared or exchanged electrons and they do that because they want to become like a noble gas, the metals will give away electrons and become positive, and the non- metals will intake the electrons and become more negative….(Meredith, HS Chem)

Breaking Bonds in the flame. Arthur, an AP Chem student, communicated the idea that bond energy is released when bonds are broken, and as a result light of different wavelengths are emitted. Arthur represented LiCl and NaCl with a dash in between the atoms of Li and Cl (Figure

24). He then inferred that NaCl has greater bond energy than LiCl from the wavelengths of the colors he saw:

…there is a certain level of attraction within the bond and therefore when it breaks, lithium chloride emitted a reddish color so the wavelength is longer and that wavelength is associate with it being red, that is what you see, because red, the color red that we see, is a longer wavelength as oppose to the sodium chloride, so when that breaks (referring to the sodium chloride) it releases a shorter wavelength and that is associate with the yellow- orange color that we saw. Now when you have a shorter wavelength that means that there is more energy being release so we can assume that within sodium chloride, the bond energy, the bond enthalpy, is greater than that of lithium chloride, and that can be determine by the wavelength. (Arthur, AP Chem)

Figure 24. Breaking ionic bonds releases energy (Arthur, AP Chem)

Another AP Chem student, Carmen attributed that the color of the flame is related to the bond strength that gets broken during the flame test.

I think depends on how strong the bond is, it releases different wavelengths of light…. I think, that the strength of the bonds will determine like the color of the flame. (Carmen, AP Chem)

Nick, a HS Chem student, provides a similar explanation as he draws Figure 25.

I think that the same thing is basically happening except that it is burning, but it is the different make up that it is burning the different (flame) colors, so

there is the copper chloride, CuCl2, in it has the chloride part too, and when the flame burns it, it could split off the copper, which would make the green color instead of the lithium chloride, which was red (Nick, HS Chem)

Figure 25. Representation of how atoms in the flame release energy (Nick, HS Chem)

Michael, a GC student, invoked that the flame caused the breaking of bonds and also the electronic transitions in the atoms.

I think the true color comes from when the reactions (sic) are broken. The flame is required to have the reaction take place and to break the bonds apart and to make the electrons jump. (Michael, GC)

Some students added to their explanations that the flame caused the breakage of bonds and that new substances were formed:

What is happening to the atoms? (Interviewer) They are rearranging, becoming different, bonding again. (Alex, HS Chem)

Jason, an AP Chem student, though of dissolving of an ionic compound as atomic release of energy, he explained as he drew Figure 26, the following:

I basically draw sodium chloride bonded together with this little line and then maybe it is put into some water and it is dissolved and that turns NaCl into sodium ions and chloride ions and the bond between the NaCl is broken, that can release energy. (Jason, AP Chem)

Figure 26. Dissolving as release of energy (Jason, AP Chem)

Lose electrons lose energy The idea that losing electrons was part of how atoms release energy was found in many students. Larry, a HS Chem student, expressed and represented this idea in Figure 27 (Right diagram).

There are like two atoms and this atom (Right diagram) has certain amount of electrons but one of them (atoms), this one (atom on left) wants this electron, so this one (left one) is taking (an electron) from this atom to this one (pointing right to left atom); so this one (right atom) is the atom that releases energy, or the electrons going up to this level (drawing arrow between levels on right atom) they can go out of the atom. (Larry, HS Chem)

Figure 27. Losing electrons as atomic release of energy (Larry, HS Chem)

Gained electrons gained energy The opposite idea that absorbance of energy occurs when electrons are gained was offered by Samantha, a UD student (Figure 28):

..so that’s my atom, I guess, and here are electrons (small circles on ellipses), and another electron will attach here (drawing arrow). By gaining the electron through the outside of the cloud, so more electrons need more energy. (Samantha, UD)

Figure 28. Absorption of energy by gaining an electron (Samantha, UD)

The same student, Samantha, included in her explanation that during the atomic release of energy, atoms may lose a subshell that would affect the size of the atom:

If the electron comes off of the electron cloud, then the electron cloud will probably lose one of those orbits and will looked like that (lower picture on right hand side) compare to that (upper left picture in Figure 29).

Figure 29. Absorption of energy by losing electrons and subshells. (Samantha, UD)

Annie, a HS Chem student, explained that atoms shrink as they release energy. And as she explained she drew Figure 30.

It starts kind of normal and as it releases energy, it gets smaller, it is the same atom but it is not the same size. (Annie, HS Chem)

Figure 30. Atomic shrinkage by release of energy (Annie, HS Chem)

Marina, an AP Chem student, draws two atoms of lithium (Figure 31); one of them has gained electrons and therefore more energy, the other one has lost electrons and hence lost energy.

This one (Lithium, on left Figure 31) has two electrons, and if it gained another electron, it would have more electrons and protons and neutrons, so it (lithium atom) would have more electrons and more energy in its outer shell, it

would be moving quicker…….This is Lithium (right diagram Figure 32), it had lost its outer shell so it lost energy that it had in it. (Marina, AP Chem)

Figure 31. Lithium atoms when electrons are gained and lost (Marina, AP Chem)

Splitting subatomic particles Some students explained that atoms release energy when subatomic particles split. Darren, a HS Chem student, explained that the more subatomic particles were split from the compounds during the flame test the more energy is also released (Figure 32).

I drew the green flame (Left diagram in Figure 32) has less protons and neutrons going, like leaving the atom itself, and for the red flame (Right diagram in Figure 32) I drew more neutrons and protons flying out of the nucleus, because red has a higher wavelength so I would think that more particles are leaving to give that wavelength. (Darren, HS Chem)

Figure 32. Splitting subatomic particles release energy during flame tests (Darren, HS Chem)

Below, Elizabeth, another HS Chem student, used the analogy of the atomic bomb and its depiction in Figure 33 to explained how atoms released energy:

This is a little atom, this is a little nucleus (smaller circle) and it is in an object zooming around, and they are hitting off of each other making energy, isn’t it like how they make the atomic bomb?, atoms hitting each other to make energy, and they hit off each other and they bounced of each other. (Elizabeth, HS Chem)

Figure 33. Atoms releasing energy by collision (Elizabeth, HS Chem)

Susan, an AP Chem student, drawed a similar depiction of sub atomic particles splitting in Figures 34.

this is an atom and its nucleus is over here (Figure 34), it’s got the electrons floating but I think what they do is that they split the nucleus apart and that’s how it releases energy (Susan, AP Chem)

Figure 34. Subatomic particles splitting (Susan, AP Chem)

Summary When asked about conventions of an energy level diagram, UD, GC and AP Chem students were more familiar than the HS Chem students. Still, many students had little knowledge of what n (principal quantum number), the negative numbers next to the energy axis, and the zero energy meant in the diagram provided. This finding has allowed the researcher to know that any energy level diagram to be use for the concept inventory should be simpler than the one use for these interviews. Also, when students were asked to chose which diagrams represented atomic emission, the all UD students chose both up and down arrows diagrams, and the majority of them provide aceptable expalnations, such as, I think both of them will be, because in each flame test that we did, we excited and relaxed electrons, the arrow up and the arrow down respectively. The different incorrect ideas that students held about the behavior of atoms were diverse. The common misconceptions found among all student samples were: forming/breaking bonds in the flame test releases energy, atoms lose electrons to lose energy, and atoms gained electrons to gain energy. The explanations that atoms release energy by splitting subatomic particles was exclusively seen in high school students, none of the GC and UD students expressed this idea. Only one high school student applied this idea to explain what happens to the atoms in the flame tests. The terminology used out of context, such as the flame acted as a catalyst, or indicator, and the flame provided the energy necessary to overcome the activation energy were expressed by some high school and GC students. The idea that the flame acted as a catalyst attributed the flame as an initiator of a reaction. The flame in the flame test was also compared to an enzyme’s activity, acting as initiator of reactions. In conversations outside the interview time, high school students mentioned that they did an ‘unknown salt’ laboratory experiment using the flame tests to identify the unknown salt. Even in these conversations a few students referred to the flame as an indicator, but only three high school students used the term indicator during interviews. During interviews, 48 out of 52 students reported being familiar with the flame test. All high school students were familiar with the flame tests. Two GC and two UD students were not familiar with the flame tests.

Below is a quote of Tatiana, an AP Chem student, that contained many of the ideas that students used to explain how atoms release energy:

Everything in the universe always wants to go to its lowest state of energy, so it will decompose and that will release energy sometimes, or like when heat is giving off through a chemical reaction, we learned a lot about how electrons kind of go together and how atoms would want to complete their octet and that’s how they go to a different energy level or they break off , how much energy it takes to break those bonds too, we talked about how much energy we need to put into it for that to happen, and how much energy is giving off when that happens too, like ionization energy, electron affinity, stuff like that. (Tatiana, AP Chem)

CHAPTER 5: THE FLAME TEST CONCEPT INVENTORY AS A TOOL TO MEASURE PREVALENT MISCONCEPTIONS OF ATOMIC EMISSION

This chapter presents data analyses to answer the following questions: • Is the data from the Flame Test Concept Inventory (FTCI) valid? • Is the data from Flame Test Concept Inventory (FTCI) reliable? • How prevalent are students’ misconceptions of atomic emission? This chapter is divided into five main parts. The first part of the chapter addresses the first question dealing with FTCI data validation. The second part of the chapter addresses the administration, descriptive statistics and discrimination of the FTCI. The third part of the chapter addresses the second question by discussing the reliability of the FTCI data. The fourth part of the chapter provides the item analysis for FTCI. The last part of this chapter discusses the prevalent atomic emission misconceptions across HS Chem, AP Chem and GC student samples in a quantitative manner.

Validating FTCI Expert content validation The first version of the concept inventory was the18-item FTCI, hereafter referred to as the Expert Alpha FTCI. It was developed based on the misconceptions identified in the qualitative interviews (Chapter 4), and written as shown in Appendix P. The ‘Expert Alpha FTCI’ (Appendix R) was given to six experts who were experienced general chemistry instructors and have an area of expertise in the fields shown below (Table 10). The experts were asked to answer three questions about these items: (1) Which question(s), if any, do you find confusing? Why? (2) Which question(s) best represent atomic emission? Why? (3) Which topic(s) were omitted that you feel need to be included to best represent atomic emission? Why? The experts’ comments are addressed in three sections: (1) Confusing items; (2) Items that best represent the concept of atomic emission; and (3) omitted aspects of the concept of atomic emission.

Table 10. Faculty’ teaching and area of expertise Expert 1: General chemistry instructor/PhD in Analytical chemistry Expert 2: General chemistry instructor/PhD in Inorganic chemistry Expert 3: General chemistry instructor/PhD in Analytical chemistry Expert 4: General chemistry instructor/PhD Bio/inorganic chemistry Expert 5: General chemistry instructor/PhD Molecular Biology Expert 6: General chemistry instructor/PhD Chemical Education research

Confusing items. The wording in some items was considered confusing and therefore was modified appropriately. For example the wording in the stem of item 3 (Figure 35) was indicated as confusing because it said that atoms gain energy by exciting valence electrons, which it is not the case; a more correct statement was suggested by the expert ‘when atoms absorb energy the valence electrons are excited.’

Original item: In the flame test of copper(II) chloride, atoms gain energy, by____ A. losing valence electrons B. gaining valence electrons *C. exciting valence electrons D. forming bonds

Modified item:

In the flame test of copper(II) chloride, what happens to the valence electrons as the compound gains energy?

A. Valence electrons are lost. B. Valence electrons are gained. *C. Valence electrons move to higher energy orbitals. D. Valence electrons form new bonds.

Figure 35. Modification of item based on expert commentary.

Another confusing item was found in one of the choices (choice C) from item 13. The stem of item 13 reads as ‘Which diagram best represents the appearance of color in the flame test?’ An expert suggested modifying the representation in choice C to be less correct. The original diagram in Figure 36, it showed the absorbance and emission of light correctly. But

75 since the question in the stem is asking for the representation of emission only, and new item that has different electronic transitions for both absorbance and emission will be less correct. Item 13C was modified as shown below (Figure 36).

Original Modified

Figure 36. Modified diagram based on expert feedback to improve the validity.

Items that best represent the concept of atomic emission. Ten out eighteen items (items 3-6, 8, 10- 11, 13-15 in ‘Expert Alpha FTCI’ (Appendix R). were considered good representations of the target concept. Items 11 and 13 were unanimously chosen as the best representations of atomic emission. These items contained a Bohr atomic model and an energy level diagram. Item 11 included a Bohr atomic model where the process of absorbance and emission were assessed. Item 13 included an energy level diagram that assessed the usage of a different representation, and specifically emission of light.

Omitted aspects of atomic emission. There were two experts’ suggestions about omitted aspects of atomic emission. One of the experts suggested to compare two to three elements of the same family that have the same number of valence electrons with the objective to emphasize how the ∆E of transitions results in different colors of emissions. Item 5 of the ‘Expert FTCI’ did compare these electronic transitions using two elements from different families, copper vs. sodium. A new item was added that compare elements of the same family, sodium and lithium (Figure 37).

A flame test for NaCl produces an orange flame, while a flame test for LiCl produces a red flame because Na+ and Li+ ______.

A. have different ionic radii B. have different ionic charges C. have different energy gaps between ground state and excited state D. are both alkali metals producing colors of similar wavelengths

Figure 37. Item added to Alpha FTCI per expert suggestion (1)

Another expert expressed a concern about item 11 that shows the Bohr model representation. The expert indicated the need to teach students that the Bohr model is really only valid for H or H-like elements. His concern was that students may be confused by the multi-electron examples used in the Expert Alpha FTCI. A new item (Figure 38) was added to Alpha FTCI with the purpose to address the limitations of the Bohr model used in the Expert Alpha FTCI (item 11).

Another student looked at the drawing in question 11 and pointed out two possible problems with the model:

i. The model works only for single electron atoms. ii. The energy levels drawn are equidistant from one another.

Which of these possible problems are limitations when interpreting the flame test? A. i B. ii C. Both are limitations D. Neither is a limitation

Figure 38. Item added to Alpha FTCI per expert suggestion (2)

The 18-item‘Expert Alpha FTCI’ was revised and modified with the addition of two new items discussed above. One of the items uses elements of the same family to assess the energy gap differences and the other item assess the limitations of the Bohr atomic model. The modified inventory, ‘Alpha FTCI’, contained 20 items and was administered to GC and UD students.

Concurrent Validity Alpha FTCI was piloted in an undergraduate institution in the fall 2011 semester in the laboratory that had GC students enrolled in five sections of the first semester of chemistry course. The Alpha FTCI was also piloted in two different UD classes, an analytical chemistry and instrumental analysis classes. A total of two hundred twenty-two GC students (M=6.61 SD=2.77), 25 UD students (M=12.56 SD=3.15) from analytical chemistry class and 19 UD students (M=12.31 SD=3.13) from instrumental analysis class took the Alpha FTCI. This version had a maximum score of 20 points. Both GC and UD students took the inventory after they were formally assessed on the topic of atomic emission during their third exam of the semester. As discussed in chapter 3, concurrent validity is a measure of whether a test is able to successfully distinguish between student samples (Trochim, 2006). The results from two one-tailed t-test demonstrated that the two UD classes were equivalent and subsequently merged together for analysis (Lewis & Lewis, 2005). A t-test indicated that UD Alpha FTCI scores were significantly higher than the GC scores (t (264) = -11.50 p=0.01), and eta square showed a large effect (η2=0.33), with 33% of the variability due to differences between groups. GC mean scores were significantly lower than the overall UD mean score (combined UD courses; M=11.5, SD=2.83) and provided a form of concurrent validity. Even though the GC and UD student samples could be distinguished, UD scores were still low with an overall mean of 11.5, which represented 57% in a 20 point-scale.

Student validation interviews In order to obtain students’ feedback and improve the way questions were asked, GC and UD student interviews were conducted. These students took the Alpha FTCI during class and gave permission to contact them with the purpose to schedule a potential interview outside class time. Five GC and two UD student validation interviews were conducted three weeks after the first administration of the Alpha FTCI. The interviews required students to solve out loud all 20 items in the Alpha FTCI. Students were asked to inform the researcher if they had any trouble understanding the terms of the inventory. They were asked to read the stem item out loud and to provide an answer of their own. Then the answer choices were uncovered, and they proceeded to choose an answer; this was done an item at a time. Students would usually choose an answer that

matched their own, unless their answer was too vague, or they could not provide an answer. Students who could not provide an answer used guessing techniques, such as elimination of the most unlikely answer, or choosing the most scientific sounding choice. Students usually did not guess the correct answer. Most comments from students suggested that they did not have problems understanding the questions. Below are the most interesting student comments that facilitated improvements in the way items were worded. A GC student thought that choice D in item 5 was the correct answer because of the term ‘wavelength’ that relates to color unlike the other terms ‘energy gaps, ground state and excited state.’ After the analysis of the student’s comments, the distractor was modified to remove the word ‘wavelength’ as shown below (Figure 39):

A flame test for sodium chloride produces an orange flame, while a flame test for lithium chloride produces a red flame because sodium and Lithium______.

Original: A. have different ionic radii B. have different ionic charges C. have different energy gaps between ground state and excited state D. are both alkali metals producing colors of similar wavelengths

Modified: A. have different ionic radii B. both form ions with +1 charges, producing similar colors C. have different energy gaps between ground state and excited state D. are both alkali metals

Figure 39. Item modified based on student feedback

Item 11 (Figure 40, left side ‘original’) provides a Bohr atomic model representation of absorption and emission of light. A UD student explained that arrow C and arrow A represented the absorption and emission of light, respectively, but he realized that ‘C then A’ was not an answer choice. The same student indicated that choice C ‘D then B’ was the best answer to item 11. Based on the student’s confusion, the representation of subshells was improved by moving the arrows inside the model, as seen in the ‘Modified’ diagram in Figure 40. To answer this item correctly, a student is expected to recognize the location of the valence electrons in n=2 as they get excited to n=3, and relaxed back down to ground state n=2.

Original Modified A student drew this model to represent the A student drew this model to represent the flame test. Which arrows best represent what flame test. Which arrows best represent what happens to the ions in the flame test? happens to the electrons in the flame test?

A. A then B A. B then A B. A then C B. C then D C. D then B C. D then B D. D then C D. C then A

Figure 40. Modified item based on student’s feedback (1)

Item 13 in Alpha FTCI (Figure 41) asked about a representation for the appearance of color in the flame test. The item was modified significantly, after a UD student explained how the distractors were confusing and how he got to the best answer. First he eliminated choice A because it did not show relaxation to the ground state. Then choices B, C and D, were considered possible answers because all of them showed relaxation of electrons. The student understood that the most accurate answers could be choices C and D because they also included the absorption step. Then the student debated between choice C and D, while comparing between emission n=4 to n=2 and n=4 to n=1: …with (choices) C and D, it looks like D doesn’t start, that’s the thing it doesn’t have to go from energy level one, you know, it doesn’t have to start in one. It could start at two and so that really is confusing, and at the same time emission 4 to 2 or 4 to 1 also they both emit something, so if that is the case, maybe I should go with B, because C and D are both saying the same thing, and B has an

exclusive kind of relaxation, and the bold in ‘appearance of color’, maybe I should go with B. (Student)

The intention of the item was to assess if a student could recognize the correct arrow representing the appearance of color in the flame test, and not to eliminate diagrams in the manner the student explained. Item 13 was not intended for students to overthink which diagram was most correct. Therefore the item was modified to only one representation instead of the original four diagrams (Figure 41).

Original Modified Which diagram best represents the appearance of color in the flame test?

A B

The red color appears during the D flame test of Lithium chloride due C to___and it is best represented by arrow__in the diagram above.

A. A A. Atomic absorbance, X B. B B. Atomic absorbance, Y C. C C. Atomic emission, X D. D D. Atomic emission, Y

Figure 41. Modified item based on student feedback (2)

Items 1 and 9 were also flagged during validation interviews because students had a hard time providing an answer of their own before the answer choices were revealed. These items assessed the symbolic representation of the flame test using written and symbolic reactions (Appendix S).

Expert Validation Alpha FTCI One expert reviewed the items of the Alpha FTCI and indicated two main concerns. The first concern was in the stem of item 15 (Figure 42) that says that the flame of another gas will be four times hotter. The expert indicated that such a flame would be about 7200K and the correct answer would be choice B ‘multiple colors including red will be seen.’ Item 15 was given in its original form to 25 UD students with an added reason tier that read ‘the reason for my answer in question (item) 15 is because…’ and two lines were provided in order to collect student written responses. Item 15 responses included: thirteen students chose A (52%), nine students chose B (36%), three students chose C (12%) and no student chose D. The results showed that approximately half the UD students chose the intended correct answer.

Original: If we replace the gas of the Bunsen burner with another gas that is 4 times hotter, will lithium chloride change into a different compound? What color will the flame(s) be?

Will lithium chloride change What color will the flame(s) be? into a different compound?

A No red B No multiple colors, including red C No single color other than red D Yes single color other than red

Modified: If we replace the gas of the Bunsen burner with another gas that is slightly hotter, will lithium chloride change into a different compound? What color will the flame(s) be?

Figure 42. Modification of an item based on expert commentary.

The stem of item 15 was modified as shown in Figure 42 (Modified). The correct answer was maintained as before because if there were only a slight increase in temperature, the emission would not be affected. A new item was added to the final version of the inventory based on the written reasons provided by UD students for item 15 (Figure 42). In the final version item 15 was renumbered to item 13, and its reason tier is item 14. This new item, item 14, is shown in Figure 43.

14. The reason for my answer in question 13 is____. A. any increase in temperature will cause ionization and change the identity of the substance B. the compound can absorb and release only certain amounts of energy C. a higher energy state will be filled, producing a different colored transition D. the compound will absorb more energy so more wavelengths will be emitted Figure 43. Item added based on students’ written responses

The second concern was found in both Items 1 and 9 of Alpha FTCI. These items assessed the symbolic representation of the flame test using written and symbolic reactions. The expert identified several multiple choice answers as correct such as the formation of oxides during the flame could be possible as shown in item 1 choice C and item 9 choices C and D (Appendix S). Given these comments and students’ difficulties in answering these questions during validation interviews, both items 1 and 9 were omitted from Alpha FTCI. Starting with the 20-item Alpha FTCI (Appendix S), given the omission of items 1 and 9 and the addition of one reason tier produced the final version of the inventory that contained a total of 19 items. Overall, the final version of the FTCI (Appendix W) had four 2-tier items and eleven 1-tier items.

Alpha FTCI Results GC descriptive statistics The 20-item Alpha FTCI (Appendix S) was administered to N=222 GC students. The responses were scored where each question was worth one point (“1-tier” scoring) and scored a second time where each of the two-tier items were worth one point together – that is, the student had to answer both the question and the reason correctly to earn the point (“2-tier” scoring). Therefore, the total possible for 1-tier scoring was 19 points while for 2-tier scoring it was 15 points. Histograms for both 1-tier and 2-tier scoring are shown in Figure 44. The score ranges, means, standard deviations, and medians are summarized in Table 11.

Figure 44. Distribution of GC total scores on Alpha FTCI (n=222)

Table 11. Descriptive Statistics for 1-tier and 2-tier GC Alpha FTCI scores

FTCI N Mean Standard Median Min. Max. Skewness Kurtosis Scoring Deviation 1-tier 222 6.61 2. 774 6 1 17 0.550 0.350 2-tier 222 5.27 2.336 5 0 14 0.478 0.418

Normality test The Kolmogorov-Smirnov (KS) test of normality was used to assess normality of the distribution of scores in this study. The KS test was chosen because the student samples sizes are above 50 (Razali & Wah, 2011). In the KS test, a significant result corresponds to p-values of more than 0.05, indicating normality. A non-significant result corresponds to p-values less than 0.05 suggesting a violation of the assumption of normality. GC results for the KS normality tests indicate that both the 1-tier and 2-tier FTCI were non-normally distributed (Table 12).

Table 12. Test of Normality for Alpha FTCI GC Distribution Kolmogorov-Smirnov Statistic Df p-value 1-tier 0.120 222 <0.001 2-tier 0.119 222 <0.001

Item Analysis for Alpha FTCI Item difficulty. Item difficulty, ρ, is defined as the proportion of students answering that item correctly. The acceptable range of item difficulty is 0.30> ρ <0.80 (Ding & Beichner, 2009). A high ρ-value (ρ > 0.8) may indicate that the item was too easy for the test’s intended student sample and may not be appropriate for inclusion in an inventory designed to elicit student

84 misconceptions. However, a low ρ -value (ρ < 0.3) does not necessarily indicate a faulty item as much as prevalent student misconception. For the purpose of this study, a well-functioning item can be answered incorrectly by the majority of students because it addresses a deep-rooted misconception. An analysis of Alpha FTCI items shows 50% of the items fell within a desired item difficulty range, and the other 50% of the items are considered difficult items (Table 13). No items were found in the easy item difficulty range. Overall the inventory was very difficult for the GC student sample. Table 13. Alpha FTCI Item difficulty Difficulty Number of Items (ρ) (%)

Difficult Items 10 (50) (< 0.30) Desired range Items (0.30-0.80) 10 (50) Easy Items (> 0.80) 0 (0) Total Items 20

Discrimination Index. Item discrimination measures how well an item differentiates between students who score relatively high or relatively low on the entire inventory (Crocker & Algina, 1986). The top and bottom 27% of scores of the entire inventory were used to measure item discrimination. The discrimination index values of D>0.3 are considered ideal (Ding & Beichner, 2009). A low item discrimination index is measured when an item is either too difficult (ρ-value <0.3) or too easy (ρ-value >0.8). The discrimination index for 60% of the Alpha FTCI items fell within the acceptable ranges of good and very good discrimination (Table 14). Meanwhile, 40% of the items did not discriminate between the top 27% of students with the highest scores and the bottom 27% of students with the lowest scores.

Table 14. Alpha FTCI Item discrimination Discrimination Number of Items (D) (%) Very Good Items > 0.40 6 (30) Good Items 0.30-0.39 6 (30) Marginal Items 0.20-0.29 5 (25) Poor Items < 0.19 3 (15) Total Items 20

Both the discrimination and difficulty were put together in Figure 45 to aid visualizing that only six items were located in both a low (marginal and poor values) discrimination and difficult range of difficulty.

Figure 45. Alpha FTCI Discrimination and Difficulty Plot

FTCI Administration

As discussed previously, the 20 item Alpha FTCI was modified to a 19 item FTCI after content validation and validation interview analyses. The FTCI (Appendix W) was administered to high school (HS Chem and AP Chem) and undergraduate (GC) chemistry students. UD students did not participate in this part of the study. Nine hundred and forty four high school chemistry students from 15 schools across the U.S took the FTCI. FTCI was administered in the students’ classrooms after directions were given to students by the instructors. These directions included voluntary participation and student consent for the use of results in research (Appendix X). As before, the FTCI was administered to

students after the target concepts were formally introduced and assessed in their own classrooms. The findings that follow include only the N=459 high school students who answered all 19 items and consented to have their results used for research. Also, GC students (N=464) from a midwestern institution took the FTCI. It was administered in the laboratory, prior to beginning an experiment. The findings that follow include only the N=362 GC students who answered all 19 items and consented to have their results used for research.

HS Chem Descriptives The HS Chem student sample histograms for both 1-tier and 2-tier scoring are shown in Figure 46. The score ranges, means, standard deviations, and medians are summarized in Table 15.

Figure 46. HS Chem distribution for 1-tier and 2-tier scores

Table 15. Descriptive Statistics for 1-tier and 2-tier HS Chem FTCI scores

FTCI N Mean Standard Median Min. Max. Skewness Kurtosis Deviation 1-tier 308 6.01 2.910 6 1 15 0.719 0.560 2-tier 308 4.29 2.344 4 0 8 0.801 0.449

Test of normality for HS Chem. HS Chem results for KS normality test indicates that both the 1- tier and 2-tier FTCI were non-normally distributed (Table 16).

Table 16. Test of Normality for HS Chem Distribution Kolmogorov-Smirnov Statistic Df p-value 1-tier 0.121 308 <0.001 2-tier 0.144 308 <0.001

AP Chem descriptives Histograms for both 1-tier and 2-tier scoring are shown in Figure 47. The score ranges, means, standard deviations, and medians are summarized in Table 17.

Figure 47. AP Chem distribution for 1-tier and 2-tier scores

Table 17. Descriptive Statistics for 1-tier and 2-tier AP Chem FTCI scores

FTCI N Mean Standard Median Min. Max. Skewness Kurtosis Deviation 1-tier 151 8.87 5.008 7 0 18 0.472 -1.167 2-tier 151 6.79 3.888 5 0 14 0.447 -1.201

Test of normality for AP Chem. AP Chem results for KS normality test indicates that both the 1- tier and 2-tier FTCI were non-normally distributed (Table 18).

Table 18. Tests of Normality for AP Chem FTCI Distribution Kolmogorov-Smirnov Statistic Df p-value 1-tier 0.170 151 <0.001 2-tier 0.181 151 <0.001

GC Descriptives Histograms for both 1-tier and 2-tier scoring are shown in Figure 48. The score ranges, means, standard deviations, and medians are summarized in Table 19.

Figure 48. GC distribution for 1-tier and 2-tier scores

Table 19. Descriptive Statistics for 1-tier and 2-tier GC FTCI scores

FTCI N Mean Standard Median Min. Max. Skewness Kurtosis Deviation 1-tier 362 7.48 3.45 7 1 18 0.483 -0.231 2-tier 362 5.48 2.73 5 0 14 0.533 -0.10

Test of normality for GC. GC Chem results for KS normality test indicates that both the 1-tier and 2-tier FTCI scores were non-normally distributed (Table 20).

Table 20. Tests of Normality for GC FTCI Distribution Kolmogorov-Smirnov Statistic Df p-value 1-tier 0.102 362 <0.001 2-tier 0.111 362 <0.001

Looking at the three distinct sample means from HS Chem, AP Chem, and GC; HS Chem students obtained the lowest scores in comparison to the AP Chem and GC students. These results also provided a form of concurrent validity to the FTCI.

Test Discrimination Ferguson‘s δ values for all FTCI by student sample (Table 21) were found within the acceptable value greater than 0.9 (Ferguson, 1949) indicating that FTCI scores had broad score distributions and good discrimination among students samples.

Table 21. Test Discrimination Power (δ) by student sample Sample 1-tier FTCI 2-tier FTCI HS Chem 0.94 0.92 AP Chem 0.95 1.0 GC 1.0 0.95

Reliability Internal Consistency per student sample As discussed in Chapter 3, internal consistency, as measured by the Cronbach alpha (α) indicates how closely the questions measure the same construct. The acceptable values are equal and greater than 0.70 (Cronbach, 1951; Ding & Beichner, 2009). The AP Chem student sample showed α values greater than 0.70, which felt within the acceptable α range (Table 28). The FTCI α values for both HS Chem and GC student sample measured less than 0.70 (Table 28), suggesting that the data were not found reliable. Although, it is common to present internal consistency coefficients in the literature for an assessment, it may not be appropriate for a concept inventory that assesses incomplete and fragmented understanding (Adams & Wieman, 2011). A chemistry concept inventory also fails the assumption of unidimensionality required by coefficient alpha because of the nature of chemistry concepts where ideas are interconnected (McClary & Bretz, 2012). In this case, the FTCI does not meet the unidimentionality assumption. It is foremost important to recognize that this study focused on student misconceptions which are fragmented as was shown in the reasoning patterns found and discussed in Chapter 4. The researcher also presents a second form of reliability, test- retest, with the purpose to show that results remained stable and consistent at two separate times. Test-retest results were found reliable under these conditions. The Kuder-Richarson (KR-20) indices were also obtained (Table 22) because KR-20 measures internal consistency taking into account a dichotomous scoring in a multiple choice test, either right or wrong, and its accepted criterion value is 0.7 or greater for group assessments. All results found with the KR-20 mirrored the results found with Cronbach alpha tests.

Table 22. HS Chem, AP Chem and GC internal consistency.

HS Chem results

1-tier FTCI 2-tier FTCI N 308 308 α 0.553 0.499 KR-20 0.554 0.502

AP Chem results

1-tier FTCI 2-tier FTCI N 151 151 α 0.868 0.829 KR-20 0.869 0.830

GC results

1-tier FTCI 2-tier FTCI N 362 362 α 0.675 0.609 KR-20 0.686 0.610

Test-Retest Reliability

Test-retest reliability was obtained, as suggested by Adams and Wieman (Adams & Wieman, 2011), with a representative sample of GC students. This was done to verify if the scores of the FTCI stayed consistent over time. First semester GC students (N=100) who took the 1st administration of FTCI during spring 2012 semester were used to determine a different type of reliability, the test-retest. This sample was composed of 52 % male and 84 % of the participants were Caucasian. The academic majors most represented in this sample were 25 % engineering, 18% kinesiology, 14% zoology and 13% chemistry majors. FTCI took students an average time of 10-15 minutes to complete. Only N=80 students responded completely to the second administration of the FTCI and were included in the test-retest evaluations below. Table 23 shows the descriptive statistics for both administrations of the FTCI. Table 24 shows that the KS tests of normality for both 1-tier and 2-tier FTCI for both the first (test) and second (retest) administrations indicated the scores to be normally distributed.

Table 23. Descriptive Statistics for the 1-tier and 2-tier FTCI Test- retest Sample 1-tier FTCI Test- Retest Administration N Mean Standard Median Min. Max. Skewness Kurtosi s Deviation

1 80 8.53 4.081 8 1 18 0.143 -0.785 2 80 8.68 3.871 9 1 17 0.210 -0.610 2-tier FTCI Test- Retest Administration N Mean Standard Median Min. Max. Skewness Kurtosi s Deviation 1 80 6.08 3.352 6 0 14 0.254 0.658 2 80 6.18 2.647 6 0 12 0.0009 0.705

Table 24. Tests of Normality for 1-tier and 2-tier Test- retest FTCI Distribution 1-tier FTCI Kolmogorov-Smirnov Administration Statistic Df p-value 1 0.091 80 0.097

2 0.084 80 0.200 2-tier FTCI Kolmogorov-Smirnov Administration Statistic Df p-value 1 0.093 80 0.086

2 0.121 80 0.005

Test-retest allows the calculation of the stability coefficient, a measure of consistency that has a recommended value of 0.70 (Adams & Wieman, 2011). The stability coefficient was obtained by measuring the Pearson correlation (Table 25) for the 1-tiered FTCI showed a strong correlation of 0.591.While the 2-tier FTCI showed a medium correlation of 0.379. The results were not as high as the recommended 0.70 value. It is possible that the three week time interval between test and retest might have influenced the slight increase in test and retest mean values by some learning gain, and subsequently lower stability coefficient.

Table 25. Correlations for Test-retest 1-tier FTCI 2-tier FTCI Pearson Correlation Pearson Correlation Statistic p-value Statistic p-value 0.591 <0.001 0.379 <0.001

Because there were two scores at two different times per student, a paired sample t-tests was measured for each the 1-tier FTCI and the 2-tier FTCI scores (Table 26). The results indicated that there was no statistically significant difference between the 1-tier and 2-tier FTCI test-retest scores.

Table 26. Student Correlations for Test-retest 1-tier FTCI 2-tier FTCI Paired samples t-tests Paired samples t-tests 2 2 Statistic df Sig. η Statistic Df Sig. η (p) -0.373 79 0.710 0.008 -0.264 79 0.793 0.005

Item Analysis Item Difficulty Item difficulty, ρ, is defined as the proportion of students answering that item correctly. The acceptable range of item difficulty is 0.30>ρ< 0.80 (Ding & Beichner, 2009). A high ρ-value (ρ> 0.8) may indicate that the item was too easy for the test’s intended population and may not be appropriate for inclusion in an inventory designed to elicit student misconceptions. However, a low ρ -value (ρ<0.3) does not necessarily indicate a faulty item as much as prevalent student misconception. For the purpose of this study, a well-functioning item can be answered incorrectly by the majority of students because it addresses a deep-rooted misconception. The majority of the FTCI items were found to be within the ideal difficulty range for all student samples (Table 27).

Table 27. FTCI item difficulty (ρ) by student sample Item HS Chem AP Chem GC N=308 N=151 N=362 1 0.37 0.56 0.36 2 0.36 0.59 0.55 3 0.18 a 0.33 0.27 a 4 0.42 0.73 0.58 5 0.33 0.47 0.29 a 6 0.27a 0.44 0.29 a 7 0.41 0.64 0.53 8 0.22 a 0.56 0.28 a 9 0.26 a 0.15 a 0.17 a 10 0.36 0.29 a 0.36 11 0.23 a 0.44 0.32 12 0.31 0.49 0.31 13 0.37 0.50 0.48 14 0.37 0.45 0.47 15 0.39 0.54 0.60 16 0.32 0.41 0.44 17 0.33 0.41 0.46 18 0.23 a 0.52 0.35 19 0.27 a 0.47 0.38 aDifficult items (ρ<0.3), beasy items (ρ >0.8), and ideal difficulty items (0.30 > ρ < 0.80) (Ding & Beichner, 2009) • Items 3, 6, 8, 9, 11, 18, and 19 were considered difficult items for the HS Chem student sample (Table 27). • Items 9 and 10 were considered difficult items for the AP Chem student sample (Table 27). • Items 3, 5, 6, 8, and 9 were considered difficult items for the GC student sample (Table 27). • No items were considered easy items for all three student samples (Table 27). Overall, item 9, which assessed the representation of the flame test using a Bohr atomic model, was a difficult question for all student samples. For the HS Chem student sample, seven items were considered difficult; this is the most items in comparison to the other student samples in the study, which could reflect that HS Chem students have the lowest level of expertise about the target topic in comparison to the other student samples. Items 11, 12, and 19 were exclusively difficult for HS Chem students; in other words, AP Chem or GC students answered these items within the ideal difficulty range. For the AP Chem student sample, two items were

considered difficult. Item 10 was exclusively difficult for AP Chem student sample, this item assessed the limitations of the Bohr atomic model. For the GC student sample, five items were considered difficult. Item 5 was exclusively difficult for the GC students. Items 3, 6 and 8 were found difficult exclusively for two of the student samples, the HS Chem and the GC students.

Item Discrimination Item discrimination measures how well an item differentiates between students who score relatively high or relatively low on the entire inventory (Crocker & Algina, 1986). The top and bottom 27% of scores of the entire inventory were used to measure item discrimination. The discrimination index values of D>0.3 are considered ideal (Ding & Beichner, 2009). A low item discrimination index is measured when an item is either too difficult (ρ-value <0.3) or too easy (ρ >0.8). The majority of the FTCI items were found to be within the ideal discrimination index range for all student samples (Table 28). Table 28. FTCI item discrimination by student sample Item HS Chem AP Chem GC N=308 N=151 N=362 1 0.33 0.20 a 0.33 2 0.40 0.85 0.53 3 0.16 a 0.76 0.26 a 4 0.45 0.37 0.48 5 0.27 a 0.85 0.39 6 0.16a 0.68 0.17 a 7 0.54 0.71 0.49 8 0.36 0.78 0.45 9 0.16 a 0.12 a 0.13 a 10 0.27 a -0.20 a 0.14 a 11 0.29 a 0.85 0.45 12 0.45 0.93 0.48 13 0.45 0.88 0.51 14 0.41 0.88 0.43 15 0.51 0.76 0.59 16 0.54 0.76 0.60 17 0.47 0.88 0.68 18 0.40 0.63 0.62 19 0.37 0.68 0.70 a Low discrimination items (D<0.3), and ideal discrimination items (D> 0.3)(Ding & Beichner, 2009)

• For HS Chem students, items 3, 5, 6, 9, 10 and 11 were found to have low discrimination. Item 10 showed a negative discrimination which correspond to having the students in the upper 27% scores preformed lower than the students in the bottom 27% . • For AP Chem students, items 1 and 10 were found to have low discrimination. • For GC students, items 3, 6, 9 and 10 measured low discrimination.

Overall, items 9 and 10 in the FTCI showed low discrimination indices for all three student sample. A closer look at these items revealed that in item 9, students are asked to represent what happens to the valence electrons in the flame test using a Bohr atomic model that a student supposedly drew. Then item 10 asked students about the limitation of a Bohr model presented in item 9, and the appropriate usage of the Bohr model to represent H-like atoms, and not multi-electrons atoms, like the ones used in the FTCI. These items were strongly recommended items in the analysis of expert comments (see Expert Content Validation). Also, GC student validation interviews showed that students, who were not explicitly guessing the answers, understood the intention of items 9 and 10. These students were strongly attracted to distractors presented in items 9 and 10, and subsequently these distractors were chosen as their final answers. These results indicate the lack of or low understanding of concepts being tested in items 9 and 10. Looking at HS Chem FTCI discrimination and difficulty plot (Figure 49), four items (items 3, 6, 9 and 11) were found within the low discrimination and high difficulty range. Also, the items as a whole are oriented towards the high difficulty area (ρ < 0.3) indicating that the FTCI was a difficult inventory for HS Chem. The items (green dots) remained close to each other in proximity, as they were grouping; this item behavior indicates that HS Chem students responded in a similar manner to each item.

Figure 49. HS Chem FTCI Discrimination and Difficulty Plot

Looking at AP Chem FTCI discrimination and difficulty plot (Figure 50), only one item (item 9) is found within the low discrimination and high difficulty range. Also, items 1 and 10 were found at the low discrimination range (D< 0.3). The majority of items (16 out 19 items) were found in the ideal discrimination and difficulty range; this indicates that FTCI was appropriate for AP Chem students in relation of the discrimination and difficulty of each item. Also, the items (red dots) remained in close proximity to each other as they were grouping; this item behavior indicates that HS Chem students responded in a similar manner to each item.

Figure 50. AP Chem FTCI Discrimination and Difficulty Plot

Looking at GC FTCI discrimination and difficulty plot (Figure 57), three items (items 3, 6 and 9) were found within the low discrimination and high difficulty range. Also, item 10 was found at the low discrimination range (D< 0.3). The majority of items (14 out 19 items) were found in the ideal discrimination and difficulty range; this indicates that FTCI was appropriate for GC students in relation of the discrimination and difficulty of each item. Also, the items (blue dots) were not in close proximity to each other, in comparison to HS Chem and AP Chem students; this item behavior indicates that GC students responded in a diverse manner to each item discriminatory and difficulty power.

Figure 51. GC FTCI Discrimination and Difficulty Plot

Point biserial Point biserial is a measure of individual item reliability and represents the correlation between the item score (correct=‘1’or incorrect=‘0’) and the overall test score. A satisfactory point biserial correlation coefficient value, rho (ρbis), is greater than or equal to 0.2 (Ding & Beichner, 2009). The majority of the FTCI items were within the satisfactory range (Table 29). • Items 3, 6, 9 and 10 were not reliable items for the HS Chem and GC student samples. • Items 1, 9 and 10 were not reliable items for the AP Chem student sample • Items 3, 6, 10 and 11 were not reliable items for the GC student sample

Table 29. FTCI Item Reliability (ρbis) by student sample Item HS Chem AP Chem GC N=308 N=151 N=362 1 0.26 0.24 a 0.29 2 0.38 0.66 0.41 3 0.18 a 0.64 0.22 4 0.35 0.37 0.40 5 0.24 0.70 0.38 6 0.15 a 0.56 0.15 a 7 0.45 0.57 0.37 8 0.43 0.63 0.46 9 0.14 a 0.09 a 0.20 10 0.17 a -0.11 a 0.13 a 11 0.31 0.68 0.42 12 0.39 0.71 0.45 13 0.37 0.64 0.37 14 0.37 0.71 0.34 15 0.43 0.64 0.45 16 0.46 0.65 0.50 17 0.43 0.74 0.54 18 0.40 0.47 0.54 19 0.37 0.55 0.58 a Low item reliability (ρbis<0.2) and ideal item reliability (ρbis> 0.2) (Ding & Beichner, 2009)

Overall, Item 10 showed low ρbis value for all student samples, mirroring the results of discrimination indices found in the previous section. In addition, item 9 showed low discrimination for both HS Chem and AP Chem student samples; this could indicate that at the high school level misunderstandings about the Bohr atomic model are prevalent. Item 6 showed low discrimination for both HS Chem and GC student samples.

Atomic Emission misconceptions Given that the distractors for each item in the FTCI were constructed from analysis of the interviews described in chapter 4, it is not surprising that additional evidence for the misconceptions discussed in Chapter 4 can be found in the FTCI results. These misconceptions were divided into categories: (a) Misrepresentations category (Table 30). ; (b) Atomic properties category (Table 31); (c) Breaking and forming bonds category (Table 32); (d) Losing and gaining electrons category (Table 33); (e) Process related category (Table 34); (f) Heuristics category (Table 35) and (g) Terminology used out of context category (Table 36).

Misconceptions within the FTCI were considered prevalent when at least 10% of the students chose a specific distractor. In this study, selecting a low cut-off of 10% would be more inclusive because of the diverse amounts of exposure to chemistry for participants. This level has been previously used with the intention that misconceptions characteristic of particular sample might have been included and analyzed (Treagust et al., 2011). Percentages of at least 10% were bolded in Tables 33-39 to emphasize the prevalence of misconceptions across student samples. These tables showed the categories and the percent students per student sample that held these categories of general misconceptions.

Misconceptions with representations The FTCI has two representations of atomic emission. One of these representations is found in item 9 of FTCI. Item 9 includes a Bohr atomic model diagram as shown in Figure 52.

9) A student drew this model to represent the flame test. Which arrows best represent what happens to the electrons in the flame test?

A. B then A B. C then D C. D then B D. C then A Figure 52. Item with Bohr atomic model in FTCI Item 9 is followed by item 10, which assessed the limitations of the Bohr atomic model. Item 10 is shown in Figure 53.

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10) Another student looked at the drawing in question 9 and pointed out two possible problems with the model:

i. The model works only for atoms with one electron. ii. The energy levels drawn are equidistant from one another.

Which of these possible problems are limitations when interpreting the flame test? A. i B. ii C. Both are limitations D. Neither is a limitation

Figure 53. Limitations of the Bohr atomic model item in FTCI

The second representation is found in item 11 of FTCI (Appendix W). Item 11 includes an energy level diagram as shown in Figure 54.

11)

The red color appears during the flame test of Lithium chloride due to___and it is best represented by arrow__in the diagram above.

A. Atomic absorbance, X B. Atomic absorbance, Y C. Atomic emission, X D. Atomic emission, Y

Figure 54. Item with energy level diagram used in FTCI Item 11 is followed by item 12, which assessed the reason students’ used for their answer in item 11. Item 12 is shown in Figure 55.

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12) The reason for my answer to question 11 is because the diagram shows ______.

A. excited electrons returning back to their ground state B. that the compound does not absorb energy from the flame C. the energy increase necessary for the color change D. the ions in the compound gaining and losing electrons

Figure 55. Reason-tier item for energy level diagram representation

Misconceptions about the representations, Misrepresentation category (Table 30) takes into account the distractors under items 9 (9A, 9B, 9D), 10 (10A, 10B, 10D), 11(11A, 11B, 11 C) and 12 (12C) in the FTCI (Appendix W). These representations included a Bohr atomic model and energy level diagram shown above. The HS Chem and the GC students held all of the misconceptions above the 10% cut-off in this category. The AP Chem students held eight out the nine misconceptions under this category above the 10% cut-off.

Table 30. Misrepresentation category

Misconceptions with representations (items) HS Chem % AP GC % Chem % Using a Bohr atomic model, electrons only absorb energy in 19.8 27.8 25 the flame test (9A) Using a Bohr atomic model, electrons only release energy in 34.4 17.9 46 the flame test (9B) In an energy level diagram, an arrow pointing up represents the 55.0 4.9 25 color appearance during the flame test because that is the energy increase necessary for the color change (11A and 12C) Ground state is always n=1 (9D) 19.5 39.7 12 Absorbance represented with an arrow down (11B) 16.2 14.6 10 Emission represented with an arrow up (11C) 32.1 23.8 26 Limitations of Bohr atomic model: The model works only for 28.6 10 20 atoms with one electron (10A) The energy levels drawn in the student’s model are equidistant 20.5 38.4 34 from one another (10B) No limitations in Bohr model or student’s drawn model (10D) 14.9 22.5 10

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Atomic properties Misconceptions within the atomic properties category (Table 31) takes into account the distractors under items 3 (3C), 4 (4A, 4B, 4D), 7 (7B, 7C) and 15 (15A, 15B, 15D) of the FTCI. These representations included a Bohr atomic model and energy level diagram. The HS Chem held all of the misconceptions above the 10% cut-off in this category. The GC student sample held eight out nine misconceptions in this category. The AP Chem student sample held four out nine misconceptions under this category.

Table 31. Atomic properties category

HS Chem AP GC % Atomic properties affecting atomic absorption and emission % Chem %

18.2 27.8 12 Ionic radii related to color of flame of a transition and an alkali metals (15A)

20.5 10.6 16 Ionic radii related to color of flame of two alkali metals (4A)

25.3 9.9 11 Charges in ions affect color of flame for a transition and an alkali metals (15B)

21.8 9.9 17 Charges in ions affect color of flame for two alkali metals (4B)

17 Types of metals affect color of flame, Alkali metals VS 17.9 8.6 transition metals (15D)

15.6 6.6 9.0 Types of metals affect color of flame: Alkali group metals (4D)

16.9 16.6 14 Location of elements in periodic table affect color of flame (7B)

23.1 6.6 17 Number of valence electrons affect color of flame (7C)

38.3 46.4 46 Absorption of energy is affected by the availability of orbitals in metals (3C)

Breaking and forming bonds The breaking and forming bonds category (Table 32) takes into account: distractors from items 2 (2D), 3 (3D), 5(5A), 6 (6A) and 8(8C). The HS Chem student sample held all these misconceptions under this category, While the GC and AP Chem student samples held four and

103 three respectively. The highest percentage is held by 60% of GC students sustaining that ‘Bonds must break to release energy’.

Table 32. Breaking and forming bonds category

HS Chem AP GC % Breaking and forming bonds affects absorption and emission % Chem %

Valence electrons are gained to form new bonds (2D) 13.3 6.6 5.5

Formation of new bonds limits absorption of energy (3D) 17.5 13.2 11

Bonds must break to release energy (5A) 40.6 19.9 60

Atoms in the flame rearranged to form a new compound (6A) 20.5 9.3 17

Bonds in the compound are broken in the flame (8C) 30.2 22.5 35

Losing or gaining electrons Misconceptions within the losing or gaining electrons category (Table 33) takes into account the distractors under items 2 (2A, 2B), 6 (6C, 6D), and 8 (8A, 8D) of the FTCI. All student samples held all of the misconceptions above the 10% cut-off in this category.

Table 33. Losing or gaining electrons category

Losing or gaining electrons as part of atoms absorbing HS Chem % AP GC % and releasing energy; and the specific color emitted Chem %

26.0 10.6 21 Valence electrons are lost (2A) 30.5 9.9 24 Valence electrons are lost (8A) 19.2 11.9 29 Atoms shrink by losing electrons (6D) 24.4 34.4 18 Valence electrons are gained (2B) 17.2 11.9 13 Valence electrons are gained (8B) 33.1 35.1 25 Atoms expands by gaining electrons (6C)

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Process related Misconceptions about the process category (Table 34) takes into account the distractors under items 3 (3A), 7 (7D), 13 (13C) and 14 (14C) of the FTCI. The HS Chem and GC student samples held all of the misconceptions above the 10% cut-off within this category. The AP Chem student sample held one out three misconceptions in this category.

Table 34. Process related category HS AP GC % Process related misconceptions Chem % Chem %

An slight increase in the energy source will not change the 19.9 8.4 22 identity of the compound and a single color other than red will be seen because a higher energy will be filled, producing a different colored transition (13C and 14C) The amount of energy that a compound can absorb in a flame 26.3 7.3 16 test is limited by the temperature of the Bunsen burner flame (3A) Color of flame is due to electrons dropping into inner energy 19.2 13.2 16 levels (7D)

Heuristics Misconceptions within the heuristic category (Table 35) takes into account the distractors under items 16 (16B, 16C), 17 (17C), 18 (18A, 18C) and 19 (19B) of the FTCI. All student samples held all of the heuristics above the 10% cut-off in this category. This category has two heuristics, the additive and the overpowering heuristics. In Talanquer’s study of heuristics, the additive heuristic tell us that students refer to the chemical product of a reaction as the result of “mixing” two substances and paid attention to the number of atoms of each type of substance to weigh the influence of each color reactant (Talanquer, 2006). In the same study students’ responses on additive reasoning combined with personal ideas about “dominance” of one property over another, the overpowering heuristic. Items 16 and 18 asked students to predict the color of the flame of the flame test of a mixture of blue and red colored substances. The substances are mixed in equal amounts (item 16) and in different amounts (item 18) respectively. Item-distractor combinations 16C and 18C represents students who chose purple as the color of flame produced. This distractor combination uses reasoning similar to the additive heuristic explained previously. Table 38 shows that the additive heuristic is used across all student samples. In the other hand, the overpowering thinking heuristic is assessed with items

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combinations 16B/17C and 18A/19B. In the combination of items 16/17 (students who chose 16B and 17C) did so by using the overpowering heuristics in terms of the greater amount of energy in color blue than color red, producing a blue color flame overall. A similar response is giving by students in combination of items 18/19. These students chose 18A and 19B in terms of the greater amount of moles of lithium chloride in the mixture, creating a red color flame overall because of the overpowering reasoning heuristic.

Table 35. Heuristics category Heuristics HS Chem % AP Chem % GC % Additive thinking (16C) 39.6 29.1 34 Additive thinking (18C) 28 21.9 18

Overpowering thinking (16B and 17C) 11.4 10.4 8

Overpowering thinking (18A and 19B) 22.1 7.1 27

Terminology used out of context The use of terminology out of context category was found in the distractors of item 1 of the FTCI. The results from the table below show that the use of the terms ‘catalyst’ and ‘indicator’ as roles of the flame in the flame test are present across the all student samples (Table 36).

Table 36. Terminology used out of context category

Terminology used out of context when role of the flame HS AP GC Chem Chem % % %

Flame as an activation energy (1A) 13.3 2.6 13

Flame as a catalyst (1B) 19.5 10.6 15

Flame as an indicator (1C) 29.9 31.1 36

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Misconception Categories within the FTCI items Another way to look at the categories of misconceptions found in Chapter 4 was to assign specific item(s) from the FTCI to each misconception category as shown in Table 37:

Table 37. Misconception categories next to its assigned FTCI items Misconception Categories Item (s) and item combination in FTCI a) Misrepresentations of atomic emission 9, 10, 11, and 12 b) Atomic properties affecting atomic absorption and emission 4, 15 c) Breaking and/or forming bonds affect absorption and emission 3, 5 d) Losing and/or gaining electrons 2, 6, 8 e) Process related alternative conceptions 7, 13,14 f) Heuristics 16,17, 18, 19 g) Terminology used out of context. 1

The HS Chem student sample held between six (37%) and seven (57%) of the misconception categories (Figure 56). This accounts for ninety four percent of HS Chem students holding at least six out of seven misconception categories found in this study.

Figure 56. Percent HS Chem students with number of misconception categories

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The AP Chem student sample held five (12%), six (37%) and seven (18%) misconception categories. This indicates that sixty seven percent of all AP Chem students hold at least five of these misconceptions categories (Figure 57).

Figure 57. Percent AP Chem students with respective number of misconception categories.

The GC student sample held six (29%) and seven (24%) misconception categories. This indicates that fifty three percent of GC students held at least six misconception categories (Figure 58).

Figure 58. Percent GC students with respective number of misconception categories.

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Summary The FTCI produce valid data for instructors’ use in assessing student misconceptions of atomic emission. The inventory items are based on flame test demonstration results given to students as a colored handout (Appendix L1). After the FTCI administration, interviewed students who reported not being familiar with the flame test indicated that the FTCI handout colored pictures were clear and self-explanatory. FTCI items shared good discrimination between students at high and low ends of the entire inventory scores for all student samples. Through the content validation stage of the FTCI where experts provided insights about the concept(s) addressed, they identified ten of the nineteen questions that best represented the concept of atomic emission. These questions were 3-6, 8, 10-11 and 13-15 (Appendix L). Only two questions, 11 and 13, were chosen unanimously by all seven experts. These two questions contained typical textbook representations of a Bohr model and an energy level diagram. The development of FTCI shed light into misconception related to challenges in regards to the representations such as Bohr atomic model and energy diagrams (items 9, 10 and 13). Interviews with HS Chem and AP Chem high school students revealed their preference for the Bohr atomic model, while explaining how atoms release energy. The seven misconceptions categories results shown in Tables 30-36 arose from the analysis of student interviews found in Chapter 4. These results showed that the misconceptions categories are representative over the range of expertise in this study.

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CHAPTER 6: CONCLUSIONS, IMPLICATIONS AND FUTURE WORK

This chapter contains general conclusions about students’ common reasoning patterns, their misconception categories, and the Flame Test Concept Inventory (FTCI) results presented in previous chapters. The chapter discusses the potential limitations of the study, as well as the implications for teaching and research in the field of chemistry education. Lastly, suggestions for classroom applications and further research are included.

Conclusions Common Reasoning Patterns When students were asked open-ended questions about what they know about how atoms release energy, the most common general chemistry (GC) dynamic mental constructs (DMCs) were given in terms of: (1) exothermic reactions; (2) bond breakage; (3) atoms moving; (4) atoms changing their state of matter; and (5) substances tendency to achieve an octet and gain stability. On the other hand, upper division (UD) DMCs were given in terms of: (1) excited electrons returning back to the ground state; (2) electrons getting excited in a quantized manner; (3) ionization; (4) a required absorbance step; (5) excited electrons returning to ground state to achieve atomic stability; (6) the energy gap between excited and ground states corresponding to the amount of energy released; (7) bond breakage in ionic compounds; and (8) fluorescence or phosphorescence. UD students presented scientifically more correct DMCs in their qualitative understanding of atomic emission during open-ended questions, but still, portions of their understanding were incorrect. For example, one UD student, Rachel, mistakenly had the idea that ionization happens during atomic release of energy. When students explained what happens to atoms in the context of flame tests, the most common GC DMCs were constructed in terms of: (1) atoms changing state of matter; (2) bonds breaking; (3) atoms’ temperature/movement determining the color of flame; (4) exothermic reactions; (5) flame as an indicator and as a catalyst for a reaction. On the other hand, UD students explained what happens to atoms in the flame test by using explanations that included: (1) excited electrons moving down to lower energy levels; (2) energy gap between excited and ground state corresponding to the color of flame; and (3) color of flame caused by different orbitals energy requirement. Again, UD students presented scientifically more correct DMCs

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while explaining the phenomenon of atomic emission given the context of flame test, but still portions of their understanding were incorrect. For example, one UD student, Lucy, mistakenly made a comparison between atomic radii and the length of the arrows that represented electronic transitions in a Bohr model. The consistency of DMCs between the open-ended questions of Phase I and the flame test context questions of Phase II showed the following: (1) the consistency of how each GC student responded to open-ended and flame test questions indicated that only two out of 14 GC students responded in somewhat similar manner, low consistency; (2) the consistency of how each UD student responded to open-ended and flame test questions indicated that eight out of 12 students responded in somewhat similar manner. In other words, UD students used similar reasoning patters to answer both open-ended and context questions with high consistency. DMC analysis showed that the level of expertise in chemistry was proportional to the level of consistency in reasoning patterns used during the interviews in this study.

Common misconception categories The constant comparison method revealed six main categories of misconceptions across high school and undergraduate students: (1) Misrepresentations of atomic emission; (2) Atomic properties affecting atomic emission; (3) Terminology used out of context; (4) Breaking and forming bonds; (5) Ionization; and (6) Splitting subatomic particles. In this study, both the inductive, Constant Comparative Method (CCM) and deductive, Mode- Node Framework (MNF) analyses of interviews produced similar results with differences focuses. MNF produced DMCs that captured how students’ build explanations, which included correct and incorrect fragments of knowledge unlike the CCM producing only students’ incorrect ideas. Furthermore, the MNF analysis of student interviews in this study revealed DMCs that were consistent with some misconceptions already reported in the literature, supporting the validity of the results. For example, the DMC mixing atoms/compounds/molecules produces a reaction. If the reaction causes bond breakage (or bond forming), then atoms will release energy, invokes the idea in students that bond breakage releases energy. Students’ conceptual confusion as to whether bond breaking or bond forming releases energy has been well documented in the literature with teachers (Kruse & Roehrig, 2005), high school and undergraduate chemistry students (Boo, 1998; Teichert & Stacy, 2002). Furthermore, the students invoking this DMC also

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emphasized the atom’s goal towards stability in relation to the breaking of bonds during reactions. This DMC contributes to the idea that atoms release energy in order to achieve stability (Taber, 2009). The DMC electrons move to higher energy orbitals causing electrons to be lost/gained hence the release of energy invokes ionization as a necessary step in the process of atoms releasing energy. Some students also mentioned atoms obtaining an octet as part of their explanations. This DMC is consistent with a study about factors affecting ionization energy that revealed undergraduate students relate the fully-filled or half-filled sub-shell as stable analogous to the ‘stable octet’ (Tan, Taber, Goh, & Chia, 2005). The ‘octet heuristic’ is a widespread explanatory framework that high school and undergraduate chemistry students develop and apply incorrectly to contexts outside of where it might apply (Taber, 2009). The DMC the flame causes substances to melt and bonds to break to form individual atoms resembles a misconception described when university students were asked to explain the terms ‘melting’ and ‘dissolving’. Forty three percent of the first year (10 out of 23) and all of the graduate (7 out of 7) chemistry students interviewed indicated that bonds would be broken during melting (Smith & Nakhleh, 2011). Although, these few DMCs had matched misconceptions related to the topic of atomic emission, all the DMCs in this study are novel and revealed misconceptions that focused exclusively on atomic emission, currently a scarce topic in misconception research. Once all interviews in this study were analyzed for misconceptions, these misconceptions were subsequently used to generate items and distractors found in the Flame Test Concept Inventory (FTCI). The development of the FTCI followed a rigorous validation stage that included a pilot version and additional student interviews. Then, the FTCI was administered to a greater number of students to find conclusive evidence that these misconceptions may be found in other student samples, which would also strengthen the validity of the inventory. Indeed, FTCI results showed that the misconceptions within the seven misconception categories, explained above, were highly appealing among the majority of students. Ninety four percent of the HS Chem, 55% of AP Chem, and 53% percent of the GC students held at least six of these seven categories. In conclusion, FTCI results showed data that are valid and reliable with GC and high school students. Therefore, the atomic emission misconceptions included in the FTCI may be generalized to other student demographics in the U.S.

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Potential Limitations It is important to recall that that both GC and UD students self-selected to participate in interviews. Rosenthal’s studies on self-selection of participants indicate different characteristics of volunteers and non-volunteers in research (Rosnow & Rosenthal, 1976). Among these characteristics, volunteers tend to manifest greater intellectual ability, intellectual interest and intellectual motivation. In the present study, students who participated in interviews may have higher grades than their non-volunteer peers, but evidence to explore this issue was not collected. Despite the volunteer characteristics in the Rosenthal studies, the misconceptions and DMCs described in Chapters 4 and 5 showed many incorrect ideas that were applied by HS, GC and even UD students while solving a given cognitive task, i.e., explaining the behavior of atoms in the context of a flame test. During interviews, when students were presented with energy level diagrams, all GC and AP Chem students were familiar with the diagrams while half of the HS Chem students sustained that they had never seen an energy level diagram, despite their teacher’s indication that these diagrams were used and assessed in class. The lack of familiarity with energy level diagrams may have played a factor in their responses during Phase III and IV of interviews for HS Chem students. The main difference was the prior knowledge between students enrolled in their first year of high school chemistry (HS Chem) vs. students enrolled in the second year of high school chemistry (AP Chem). HS Chem students that expressed familiarity with energy level diagrams had a hard time recognizing the symbols and/or conventions used in this representation, and others used the meaning of similar symbols in chemistry and applied them to the energy level diagram, for example a HS Chem student explained the meaning of ‘n’ in the energy level diagram ‘Moles, because that’s how we used to represent moles in class’, Ausubel and Novak’s theory indicates that learning will be meaningful only when the new idea or concept to be learned can be purposefully connected to the student’s relevant concepts and ideas. The creation of these student experiences should be a key component during class preparation. Teachers should consider students’ infrequent exposure to abstract chemistry concepts, like the concept of atomic emission or energy level diagrams, which do not have an everyday counterpart. These experiences can be acquired as more chemistry expertise is obtained, something that HS Chem students were still developing.

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The items in the FTCI were harvested from the misconceptions found in interviews and represented various levels of expertise, from high school to upper division chemistry students. During student validation interviews only GC and UD students participated, this occurred because these students were a convenient purposeful sample, they were available, willing to participate, and the researcher secured IRB approval for these interviews. High school student validation interviews were not possible due to IRB constrains, therefore this could have been a potential limitation in this study. To alleviate this limitation, high school teachers were given the inventory previous to its administration with a dual purpose: to check if the topics were assessed in class and if the inventory was adequate for his or her students.

Implications for Teaching MNF and Class Discussion With regard to implications of this research for classroom teaching, the Mode Node Framework (MNF) analyses of interview dynamics (Chapter 4) served as a lens into students’ reasoning and building of explanations. Interview dynamics can be compared to classroom discussions. During such discussions, teachers encounter great pedagogical demands such as understanding how students make sense of a proposed task while at the same time beginning to align students’ fragmented ideas with the correct understanding of a specific concept (Leinhardt & Steele, 2005; Sherin, 2002). Recognizing that students engage in shifting and skimming modes can sensitize teachers to probe for student understanding beyond initial answers. If the teacher is aware of student explanations prior to classroom discussions, then these discussions may clarify or correct students’ ideas. Stein, Engle, Smith and Hughes (2008) have developed a pedagogical model built with the objective to help teachers orchestrate productive whole-class discussions. This model indicates the need for teachers to be aware and anticipate students’ potential answers before class discussions. The findings described in this study (Chapter 4) provided potential student responses and/or relevant prior knowledge about atomic emission and/or flame test demonstrations that could arise during class discussions. The findings of this research also contribute to the constructivist body of literature that teachers can use to learn more about their students’ prior knowledge of atomic emission.

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MNF and Representations Asking students to draw their own representations provides drawing nodes that can be discussed by the whole class as an opportunity to identify multiple modes for understanding representations or in-class demonstrations. In this study, a simplified version of an energy level diagram was the focus of assessing student understanding of symbols and conventions, the basic elements of a representation proved to be challenging for students.

FTCI and Assessment Prior to and during instruction instructors are encouraged to assess student understanding before comprehensive evaluations take place. A concept inventory (CI) can be used as a formative assessment. The FTCI is a multiple choice concept inventory that may be administered in a classroom after formal instruction, similar to the data collected in the current study. FTCI is an easy to administer CI that requires about 10-15 minutes, but if an instructor has a more limited time in class, he/she may select the questions experts selected for in-class discussion, or as a formative assessment such as in classroom response systems e.g. ‘clicker’ questions (Iowa, 2012). The FTCI was created from the analysis of fifty-two student interviews at various levels of chemistry expertise: high school, first year general chemistry and upper division chemistry students. All distractors (incorrect answers) to FTCI questions were obtained from students’ explanations and slightly modified to fit the inventory. Therefore, an instructor could gauge how his/her class, as a whole, resembles typical results from the high school and/or general chemistry classes provided in this study (Chapter 5).

FTCI and Representations Through the content validation stage of the FTCI, where experts provided insights about the concept covered, they identified questions that best represented the concept of atomic emission. These questions are found in the final version of the FTCI as items 2-5, 7-9, 11-13 (Appendix W). Only two questions, items 9 and 11, were chosen unanimously by experts as best representations of the target concept. These two questions contained typical textbooks representations of a Bohr model and an energy level diagram. If an instructor has limited time in class, he/she may select these questions for in-class discussion. The prevalent used of Bohr

115 atomic models by high school students, who were also familiar with energy diagrams during interviews, reflected their Bohr atomic model preference when representing atomic behavior. The FTCI includes the Bohr atomic model because students bring these preferences to their first year chemistry classrooms, and instructors can assessed or start discussions about the limitations of models. Question 10 of the FTCI which assessed the limitations of the Bohr atomic model showed that 29% of HS Chem, 10% of AP Chem, 20% of the GC chose only one of the two limitations presented in the FTCI, the model works only for atoms with one electron. Therefore it is suggested that instructors aid their students in a transition into the use of other models, instead of having these models the Bohr model and energy level diagrams presented as totally separate models. For example, teachers and students can explore the common features, the differences and limitations for both the Bohr model and energy level diagram.

Flame Test and Student Engagement Educators looking for ways to intrigue and engage students can do so by the use of in- class demonstrations. Demonstrations can be useful for creating cogent mental links between chemistry concepts and real world applications, initiating class discussions while creating personal relevance to the topic at hand, and encouraging collaboration between students and instructors to ask questions and seek ad-hoc solutions (Meyer et al., 2003). As observed during interviews in this study, students were easily engaged with flame test demonstrations. An AP Chem student expressed it in the following manner ‘Ok, sodium chloride when flamed it emits a yellow-orange color flame, yellow wavelength of light, it’s soo cool, I want to keep doing that, hee hee’. The engagement factor created by flame test demonstrations positively influences the affective domain of Novak’s theory, and provides an opportunity for instructors to facilitate students’ meaningful learning. Therefore instructors using flame demonstrations in addition to energy diagrams at both the high school and undergraduate classes have the potential for increased student engagement. A flame test demonstration brings the opportunity to observe a phenomena in-class. Students are aware of their observations and could engage in informal explanations. These explanations could be guided towards explaining what happens to the atoms in the flame test. Students’ explanations of the behavior of atoms are presented in this study in the form of DMCs. For example, a common student explanation refers to atoms absorbing energy in the flame,

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which causes electrons to be promoted to higher energy levels and/or escape the ‘electron cloud’. The idea that electrons are lost during a flame test could be refuted by the teacher by bringing evidence of the temperature of a standard Bunsen burner (~1200 K) which is not enough energy to reach the first ionization of sodium. Teachers should emphasize the correct pieces of explanations, and aid to avoid the use of out of context knowledge. As with any representation, the flame test also has its limitations. When demonstrating to students, teachers should note the fact that not all atomic emission happens at the visible range of the spectrum because other types of emission are found at a lower range, such as infra-red, or at a higher range, such as ultra violet. The representations of flame tests, energy level diagrams, and student created Bohr atomic models were used to assess the connections between the macroscopic, symbolic and particulate representations of atomic emission as emphasized and discussed by Johnstones’ Domains. These disconnections between domains reflected the misconceptions found in Chapter 5. Implications for Chemistry Education Research As discussed previously, topics related to atomic emission are formerly covered in the K- 12 U.S. curriculum from 5th grade through high school science classes (College Board, 2012; National Research Council, 1996). During the first year of undergraduate chemistry and physics classes, quantum principles are taught more extensively. Research studies about topics related to atomic emission (Cervellati & Perugini, 1981; McKagan et al., 2008; Orgill & Crippen, 2010; Tsaparlis & Papaphotis, 2009) such as orbitals, atomic models and representations are present in literature, however, CER literature is silent with regard to students’ qualitative understandings of atomic emission, an important topic that finds its highest coverage in the analytical chemistry curriculum. The present study addresses this gap in the literature. The MNF analysis (Chapter 4), on student interviews is the first known instance of using this framework in the field of Chemistry Education Research (CER). Through MNF analysis, this study was able to focus on how students reasoned and constructed ideas using their prior knowledge when presented with a cognitive task. The manner in which students articulated their explanations about atomic emission was captured in the DMCs. Currently in CER, there are not studies that focus on how students expressed their misconceptions or fragmented ideas, similar to the MNF framework utilized in this study.

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Having a large set of misconceptions about different topics in general chemistry is useful for instructors, but understanding how students explained these fragmented ideas is also a key component of evaluating teaching and learning. In the field of misconceptions research, concept inventories represent tools that can be used by instructors. The present study focused on the development of a concept inventory, FTCI, from interviews. These interviews represented very distinct student samples. The development of FTCI accounted for twenty-six high school student interviews and twenty-six undergraduate student interviews. The richness of the data was found on the diversity of chemistry expertise obtained from interviews. Therefore, FTCI is one of the few concept inventories in Chemistry Education Research (CER), to the best of the researcher’s knowledge, which has been validated for both high school and undergraduate chemistry classes. In this study, the FTCI results should appeal to researchers and instructors of chemistry classes within the undergraduate analytical curriculum, where it is assumed that students held correct qualitative understanding of atomic emission. Future Work

Students’ Building of Scientific Explanations The findings presented in Chapter 4 emphasized the importance of paying attention to students’ underlying reasoning and construction of explanations in the analysis of interviews conducted for the purpose of identifying misconceptions. These MNF findings point to potential areas of future research. For example, research focus on how student built scientific explanations of phenomena (i.e. burning, melting, oxidation) at different stages of formal education, and the connections students make to fragmented pieces of knowledge within and across chemistry and other disciplines.

Teachers’ misconceptions about Atomic Emission While some misconceptions have their origins outside of the classroom, many begin in class where students are exposed to chemistry topics for the first time. It is possible that some misconceptions transfer from teachers to students. There are a few studies that focus on pre- service high school teachers’ misconceptions, on topics such as phase and chemical equilibrium, ionization energy, vapor pressure, and chemical reactions at the particulate level (Azizoglu et al., 2006; Canpolat, Pinarbasi, & Sözbilir, 2006; Cheung, 2009; Tan & Taber, 2009). There are even

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fewer studies that focus on university instructors’ misconceptions (Lee, 1999). Two separate studies from Singapore gave pre-service high school teachers and students the same concept inventory, the ionization energy inventory (Tan et al., 2005; Tan & Taber, 2009). Findings in those studies resembled each other; in other words, the misconceptions that teachers and students had were almost identical. As was done in previous studies, the FTCI could similarly be given to pre-service high school teachers and general chemistry faculty, and their results could be compared to the students’ misconceptions presented in this dissertation.

Teaching Applications This study focused on two main themes: identifying student misconceptions of atomic emission (FTCI) and identifying how student construct explanations about atomic emission (MNF). A series of practical teaching applications could be part of future work. The emphasis in the use of demonstrations at the undergraduate level is rare (Meyer et al., 2003), a guided activity may be created for students to solve after flame test demonstrations are presented in class. This guided activity should include class discussions facilitated by an instructor, who is well aware of the reasoning patterns student used to explain flame tests. FTCI may be used to measure learning gains if any, after flame test demonstrations and class discussion have taken place.

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Appendix A Cognate Manuscript for Journal of Chemical Education Flow injection analysis and liquid chromatography for multifunctional chemical analysis (MCA) systems

Ana V. Mayo, Thomas N. Loegel, Stacey Lowery Bretz, Neil D. Danielson*

Miami University, Department of Chemistry and Biochemistry, Oxford, OH 45056

*corresponding author: [email protected]

Abstract

The large class sizes of first year chemistry labs makes it challenging to provide students with hands-on access to instrumentation because the number of students typically far exceeds the number of research grade instruments available to collect data. Multifunctional chemical analysis (MCA) systems provide a viable alternative for large scale instruction while supporting a hands-on approach to more advanced instrumentation. This study describes how the capabilities of MCA systems are extended to introduce liquid chromatography (LC) and flow injection analysis (FIA) in undergraduate laboratories. A semi- micro plastic cuvette with a Teflon tubing insert is fashioned as the flow cell for a MCA absorbance/fluorescence detector. Two MCA systems, Vernier and MeasureNet, are used in two unique experiments demonstrating the detection of salicylate in aspirin tablets by FIA and the LC separation of a mixture of riboflavin and fluorescein. Both instruments, composed of a syringe pump, T-injection valve, and the MCA detector operated in the kinetic mode, are rugged and inexpensive permitting student construction, if desired.

Keywords

Liquid chromatography, flow injection analysis, multifunctional chemical analysis, Beer and Lambert law, reverse chromatography.

Introduction According to U.S. Census Bureau projections, the number of college-age individuals (ages 20–24) is expected to grow from 21.8 million in 2010 to 28.2 million by 20501. The enrollment of students in science and engineering degrees is also rapidly increasing2. These trends suggest that chemistry educators can expect to teach larger lecture and laboratories classes in general chemistry for the foreseeable future. Providing student access to modern instrumentation during the first year chemistry laboratory presents a logistical challenge given the ratio of large number of students to the few (if any) research grade

132 instruments available for students enrolled in these laboratories. One alternative is the acquisition of a multifunctional chemical analysis system (MCA)3,4,5 such as MeasureNet6 or Vernier7. These systems are robust and typically use student stations connected to a remote central computer for data collection, minimizing the need for computers at every student workspace. These systems are excellent for group instruction because students can share apparatuses and solutions, but still collect their own data. MCAs offer multiple measurement capabilities, including absorbance, fluorescence and turbidity, with detectors having kinetic options. Recently, MCAs have been used to develop several undergraduate experiments, such as measuring the absorbance of a reaction that changes color as a function of temperature8 or finding an unknown concentration of copper in various pennies of world currency9. The experiments described herein use an MCA system for flow injection analysis (FIA) to introduce students to the Beer-Lambert law with the objective to measure an unknown concentration of salicylate in a sample of aspirin after hydrolysis (experiment 1). Two different MCA systems are then used to provide an introduction to liquid chromatography (LC) through the separation of riboflavin and fluorescein on a solid phase extraction (SPE) cartridge using both absorbance and fluorescence detection modes (experiment 2). The principles of flow injection analysis (FIA) have been previously presented by Hansen and Ruzicka10, 11, as well as a published description of how to construct an FIA detector for absorbance measurements with a light-emitting diode (LED), photodiodes (PD), and Legos13. Additional experiments describe the construction of a three piece injector commutator made of poly(methyl methacrylate), and a spectrometer equipped with a flow cell constructed from tubing that attaches to a glass tube that crosses a cuvette for the determination of hypochlorite12 and pyridylazo resorcinol (PAR) complexes14,15. Simple liquid chromatography (LC) instruments have previously been reported using Sep-Pak cartridges and a disposable syringe16, where both the sample (e.g., colored dyes) and the solvent were injected into the cartridge, using the human eye as the detector. Food coloring dyes were separated using a C-18 solid-phase extraction (SPE) column and different mobile phases16. SPE cartridges have also previously been used to separate dyes while demonstrating different retention mechanisms (i.e. normal, reversed, size exclusion and ion-exchange mechanisms). Students inject both the sample and appropriate mobile phase to elute different fractions; the colored dyes or precipitated anions are easily distinguished after the separation of the mixture17. Homemade columns for separation have also been created from a 40-cm Pyrex tubing glass filled with packing material reclaimed from C-18 Sep-Paks, and then attached to a conventional liquid chromatograph for the separation of food coloring18. To the best of our knowledge, inexpensive FIA and LC instrumentation has not been developed for MCA systems. The driving force for the work reported below is to describe how the current capabilities of MCAs can be extended through the addition of (1) FIA and (2) LC, using two different MCA systems.

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The development of an inexpensive flow cell used with the MCA detector in the kinetic mode provided the means to create two laboratory experiments using important, but under-utilized, low pressure LC components. These experiments provide an economically viable alternative to FIA and high performance LC instruments for large numbers of students through use of an MCA system. Detailed student and teacher guidelines for the FIA and LC experiments are provided in the supplementary material. Given that LEDs are the major sources for MCA colorimeter /fluorometer detectors, polychromatic calibration curves19 based on wavelength emission bandwidths for different LEDs were explored by the students. Post-lab questions targeted the effects of non-monochromatic light on the Beer-Lambert law, making these non-intuitive deviations of the Beer-Lambert law more student-friendly.

Apparatus Both experiments share a similar experimental set up (Figure 1). We constructed a homemade flow cell from Teflon tubing and a low volume semi- micro plastic cuvette (Figure 1A). The light crosses the Teflon tube twice giving a path length of 3.2 mm. A semi-micro VWR disposable cuvette K1948 PMMA was used for all our measurements. Other cuvettes were tested and compared (see FIA teacher guidelines). The pump, which can be either syringe or peristaltic, delivers a constant low flow rate between 0.5- 1.5 mL per minute of the carrier solution or mobile phase. A 10-mL plastic disposable syringe is used to inject the sample through a low pressure T injection valve that is connected with Tygon® tubing to the low-volume plastic cuvette flow cell housed in the colorimeter detector (Figure 1B). The vertical orientation permits a more even separation. The specifications for the spectrophotometer /fluorimeter detectors in the MCAs used in this study can be found in Table 1. In the LC experiment 2, an SPE C-18 cartridge is introduced between the injector and flow cell set up described in the FIA experiment, thereby providing LC capabilities to separate riboflavin and fluorescein (Figure 1C).

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Figure1. A: Flow cell (photos) requires 20 cm length (going in and out of a low-volume cuvette). Diagram B: FIA experiment 1 (FIA lab 1). Diagram C: LC experiment 2 set up: pump with mobile phase (MP), syringe containing sample to be injected, SPE (C-18 Sep-Pak cartridge), S (sample cuvette), R (reference cuvette), second syringe containing MP for reference cuvette. This set up utilizes the MeasureNet detector. The Vernier detector contains only one cuvette; therefore subtracting the background of mobile phase must be done before taking sample readings.

Two SPE (Alltech) syringe cartridges were compared: (1) Prevail C-18 modified silica, 11 % C, 100 % water wettable, 900 mg bed weight, 4 mL column size. (2) Maxi-Clean™ C18 modified silica, 6 % C, general purpose phase, 900 mg bed weight, 4 mL column size. Both cartridges are available from Grace (Deerfield, IL).

MeasureNet Vernier Detector Two photodiode sensors. Allow for Linear CCD array dual beam ratio metric measurements. Spectrophotometer Three LED’s: Red (630nm), Green Tungsten halogen, wavelength Range: 380 nm–950 nm (525 nm), and Blue (472 nm)

Fluorimeter 370 nm at 90° Two LED’s (405 and 500 nm) at 90° Table 1. Specifications for detectors and light sources for two MCAs. Vernier’s specifications were obtained from the company website7 and Czegan and et al5 . MeasureNet’s specifications were obtained from local representatives and company website6

Chemicals and Hazards: Iron nitrate is an oxidizer and should be handled with goggles, gloves, and under a vent hood. Nitric acid is a very corrosive and should also be handled with goggles, gloves, and under a vent hood. Sodium salicylate might cause irritation to the respiratory tract. Riboflavin and fluorescein may be hazardous in case of ingestion. Methanol, a flammable and volatile solvent, may be harmful if swallowed,

135 inhaled, or absorbed through the skin. It can cause eye, skin, and respiratory tract irritation.

Experimental Procedure and Results A) Flow Injection Analysis Experiment Although aspirin is commonly used as a preventive measure against heart attacks and stroke, particularly for men, accidental salicylate poisoning can occur in children from an overdose of aspirin. The Food and Drug Administration (FDA) has an established tolerance of 0.10% salicylic acid in unbuffered aspirin20. Salicylic acid is formed from the hydrolysis of an aspirin tablet in stomach acid. Figure 2 shows the formation of a purple complex when salicylic acid reacts with ferric ion; the resulting absorbance of visible light by the complex can be measured.

OH + 3+ + O + 2H3O + Fe H O O ( 2 )6 Fe(H2O)4 OH O

Salicylic acid Iron (III) salicylic acid complex ur e (p pl ) Figure 2. Reaction of salicylic acid with iron (III) to form a purple complex

Figure 3. UV-Vis of iron (III) salicylic acid complex (purple solution) in FIA experiment 1.

A series of known salicylate concentrations are injected into the carrier stream composed of ferric nitrate dissolved in 0.01 M nitric acid. In the flow cell the reactants mix virtually instantaneously21 to form the iron (III) complex (Figure 3). The spectrum of the iron complex formed in (Figure 3) permits 136 identification of the wavelength of maximum absorbance and can be matched to the best wavelength available in the MeasureNet MCA, the green LED. A calibration curve of absorbance vs. concentration of salicylate can be quickly generated and used to calculate the unknown concentration of salicylic acid in one or more tablets of aspirin. The aspirin should be hydrolyzed in 0.1 M HCl (simulated stomach acid) at an elevated temperature, between 37 to 43 degrees Celsius (simulated stomach temperature of a healthy or feverish child) for at least one hour. Our control aspirin sample showed 1.14 % and the experimental aspirin sample 1.23 %. The limit of detection for MeasureNet is about 2 ppm. Our students can obtain larger % salicylate conversions of about 15-25% at elevated temperatures about 70 °C at 20-30 min. This experiment can be completed in one-3 hour laboratory (see teacher guidelines). The linear regression analysis equation (absorbance (y) versus ppm (x) for n= 6 was (y) = 6.4 x 10 -4 (x) + 1.8 x 10-3 with R2 = 0.99202. The actual plot is shown in the FIA teacher guidelines. Given that light emitting diodes (LED) are the major components of the colorimeter detector used in MeasureNet MCA system, the effects of non-monochromatic light are discussed in both the pre-lab and post-lab assignments. Student-generated Excel spreadsheets in the pre-lab assignment provide the opportunity to explore the effects of changing both the molar absorptivity and the concentration of a substance on the transmittance. The pre-lab also incorporates a student-friendly model that uses the corpuscular theory of light22 to consider the probabilities of photons being transmitted through one layer of a finite path length and their capture in a second layer. The FIA experiment can conveniently introduce this concept. In the case of the Vernier MCA system (a CCD array), the wavelength interval specifies 1nm between reported values (collects 570 values)7. This wavelength interval is the source of non- monochromatic effect at the detector and ultimately what limits linearity. In the post-lab assignments, the effects of the bandwidths of green LED versus red LED sources on the molar absorptivities (slopes) for Fe (III)-salicylate are analyzed at different wavelengths and concentrations, similar to Figure 4 below. After modeling the changes in molar absorptivities, it is clear that while either LED could be selected in the MCA colorimeter, less variance in the slope is more desirable in order to reduce non-monochromatic effects on the Beer-Lambert law. In addition, bromothymol blue, a dye more difficult to measure spectrophotometrically using a LED source, is evaluated as a written exercise (see FIA student and teacher guidelines).

B) Liquid Chromatography Experiment As mentioned previously, the FIA instrument in experiment 1 can be easily modified by the addition of an SPE cartridge C-18 after the injection site, converting it into the LC instrument (Figure 1). This instrument is used to separate two similar light yellow colored dyes, riboflavin and fluorescein, through a

137 reverse phase separation mechanism using an optimum 60:40 water:methanol degassed mobile phase propelled through the SPE cartridge using a syringe pump. If a 50:50 water:methanol mobile phase is used, then both dyes have shorter retention

Figure 4. Author’s generated graph showing polychromatic effects on iron complex absorbance using red and green LEDs. MeasureNet specifications, maximum emission wavelength with full width at half maximum (FWHM) of light intensity emission peak: Red LED = 635 (FWHM 15nm); Green LED = 515 (FWHM 30nm). times, and we see lower peak resolution with peak overlap, particularly using the lower % C stationary phase cartridge. The class should be divided into groups, with each group trying a different mobile phase composition. The chromatograms from each group can then be shared among the class. Experiment 2 requires one-3 hour lab, working in groups of 2 to 3 students with requiring duplicate runs for mixture separation. In the pre-lab assignment, students are provided background chromatography information with references and asked to predict retention orders based on the chemical structures provided (see LC student and teacher guidelines). Both absorbance and fluorescence intensity were measured using two different MCA systems, namely MeasureNet and Vernier. All samples are suggested to be run at least in duplicate (Figure 5); modest reproducibility was likely due to manual loadings and possible slight initial positioning differences of the sample band in the small SPE column after each injection (Table 2). Figures 6 and 7, show chromatographic separations of 10-4M riboflavin and 10-3M fluorescein using both MCA systems, with the same mobile phases, but with different SPE cartridges. Note that the higher C18 coverage for the Prevail SPE cartridge as compared to the MaxiClean cartridge proportionally increases the retention time for fluorescein (Figures 5, 6). Differences in the signal to noise ratio were compared for both MCA systems with the MeasureNet signal to noise ratio being 1100 times greater than that for Vernier in the absorbance spectra.

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Figure 5. Author’s separation of a 2:1 mixture of Riboflavin and Fluorescein using the absorbance mode in Vernier system and Maxiclean SPE cartridge. 60:40 water:methanol mobile phase. 1 mL/min flow rate. 0.2 mL sample injection.

Reproducibility Results of 2 MCAs MCA Absorbance Detector Fluorescense Detector

k’R k’F α k’R k’F α

MeasureNet 2.47 ±0.53 7.86± 1.10 3.22 ± 0.33 1.73± 0.22 5.72± 1.1 4.3± 0.60 Vernier 0.78± 0.17 3.35± 0.48 3.29± 0.34 0.94 ± 0.27 3.16± 0.53 3.56± 1.3

Table 2. Comparison of two MCA systems. k’R and k’F are riboflavin and fluorescein retention factors respectively, averaging triplicate runs. The retention factor was calculated using k’ = (t -tM)/tM where t is the retention time of the dye and tM is the unretained peak, the refractive index mismatch of sample solvent and mobile phase. k’R and k’F calculations should not vary if same cartridge is used for all runs. α is the column selectivity α=k’R/k’f . MeasureNet absorbance and fluorescence data:

Prevail SPE cartridge. Vernier absorbance and fluorescence data: Maxi-clean SPE cartridge. Author’s results were used for all calculations.

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Figure 6. Student’s separation of 2:1 mixture of riboflavin and fluorescein using the MeasureNet detector in the absorbance mode and the Prevail SPE cartridge. 60:40 water:methanol; 1 mL/min.

Figure 7 shows a student’s chromatographic separations of 10-4M riboflavin and 10-3M fluorescein using fluorescence detection. A 370nm excitation wavelength was used for MeasureNet, specified by the LED. Similarly, a 405nm excitation wavelength was specified by the Vernier detector although the 530.5 nm emission wavelength was chosen. The chromatogram using the Vernier detector in the fluorescence mode is shown in the LC teacher guidelines. MeasureNet provided a 7.7 times greater signal to noise ratio in the fluorescence spectra.

Figure 7. Students’s separation of 2:1mixture of riboflavin and fluorescein using the MeasureNet detector in the fluorescence mode and the PrevailTM SPE cartridge. 60:40 water:methanol; 1 mL/min. Discussion The 1997 NSF report from the Analytical Science Digital Library23 called for a thorough understanding of analytical processes in an effort to improve the analytical chemistry curriculum. NSF also called for the exposure of analytical techniques early in the undergraduate laboratory in both 2 and 4 140 year schools. Exposing first year classes to analytical instrumentation concepts provides a rich base of knowledge early in the analytical curriculum. This study exposes students to the underutilized concepts of liquid chromatography and flow injection analysis. Both experiments can be used sequentially or independently and have been piloted both ways with first-year non-majors and first-year honors chemistry students. They have been well received by students who appreciated the straightforward FIA experiment 1 and a more open-ended lab LC experiment 2. Although these experiments were created for first-year students, upper-level undergraduates could also carry them out, particularly at institutions that do not provide access to research-grade instruments. The primary modification of the colorimetric salicylate experiment, from a manual standard cuvette method that has yielded good student results for many years, to one with a flow cell is that it allows the introduction of the underutilized FIA technique during a first year laboratory course. To perform these experiments, students must literally assemble the key parts themselves, thereby removing the “black box” view of instrumentation. In addition, students are able to compare the advantages and disadvantages of both manual standard cuvette and FIA techniques if time allows. One advantage of FIA is acquisition of data in a shorter amount of time; therefore students can collect multiple sample data sets. One disadvantage is the loss of sensitivity due to the shorter path length of our flow cell design. For the LC experiment, students may have to troubleshoot multiple variables to increase resolution or solve unforeseen problems. Some students also tried to separate other dyes such thymol blue and methyl orange, taking advantage of the full spectrum that the Vernier provides using the CCD, and selecting the most viable LED available using MeasureNet. This study not only shows experiment versatility and compatibility with multiple MCA systems, but also extends the capabilities of an MCA system using rugged and inexpensive materials that can easily be built by the student, if desired, to create interesting experiments.

Literature Cited 1. Science and Engineering Indicators: 2010.Chapter 2. Higher Education in Science and Engineering. Undergraduate Education, Enrollment, and Degrees in the United States. http://www.nsf.gov/statistics/seind10/c2/c2s2.htm (accessed Feb 2012). 2. Science and Engineering Indicators: 2010.Chapter 2. Higher Education in Science and Engineering. Highlights. http://www.nsf.gov/statistics/seind10/c2/c2h.htm (accessed Feb 2012). 3. Vannatta, M. W.; Richards-Babb, M.; Solomon, S. D. J. Chem. Educ. 2010, 87 (8), 770-772. 4. Sprague, E. D.; Voorhees, R.; McKenzie, P.; Alexander, J. J.; Padolik, P. J. Chem. Educ. 1998, 75 (7), 859-859. 5. Czegan, D. A. C.; Hoover, D. K. J. Chem. Educ.2012, 89 (3), 304-309. 6. MeasureNet: The new element for your science lab. http://www.measurenet-tech.com/ (accessed April 2012). 7. SpectroVis Plus Spectrophotometer. http://www.vernier.com/products/sensors/spectrometers/svis-pl/ (accessed April 2012).

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8. Nyasulu, F.; Nething, D.; Barlag, R.; Wise, L.; Arthasery, P. J. Chem. Educ. 2012, 89 (4), 536-539. 9. Novak, M. J., Yasmin; Bear, Dee Dee. General Chemistry Laboratory Manual CHM 144. Hayden McNeil: Oxford, Ohio, 2011-2012; pp 117-126. 10. Hansen, E. H.; Ruzicka, J. J. Chem. Educ. 1979, 56 (10), 677. 11. Růžička, J.; Hansen, E. H.; Ramsing, A. U. Analytica Chimica Acta 1982, 134 (0), 55-71. 12. Ramos, L. A.; Prieto, K. R.; Cavalheiro, É. T. G.; Cavalheiro, C. C. S. J. Chem. Educ. 2005, 82 (12), 1815. 13. Carroll, M. K.; Tyson, J. F. J. Chem. Educ. 1993, 70 (8), A210. 14. Betteridge, D. Fresenius' Journal of Analytical Chemistry 1982, 312 (5), 441-443. 15. Rocha, F. R. P.; Nóbrega, J. A. The Chemical Educator 1999, 4 (5), 179-182. 16. Bidlingmeyer, B. A.; Warren, F. V. J. Chem. Educ. 1984, 61 (8), 716. 17. O'Donnell, M. E.; Ca, D.; Musial, B. A.; Bretz, S. L.; Danielson, N. D. J. Chem. Educ. 2009, 86 (1), 60. 18. Sander, L. C. J. Chem. Educ. 1988, 65 (4), 373. 19. Smith, R.; Cantrell, K. J. Chem. Educ. 2007, 84 (6), 1021. 20. Chalasani, N.; Roman, J. Jurado, R. L. Southern Medical Journal 1996, 89 (5), 479-482. 21. Mansour, F.; Shafi, M.; Danielson, N. D. Talanta 2012, in press. 22. Bare, W. D. J. Chem. Educ. 2000, 77 (7), 929. 23. ASDL Analytical Sciences Digital Library. http://www.asdlib.org/aboutASDL.php (accessed April 2012).

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Appendix A.1

Supplementary Materials Student FIA

FLOW INJECTION ANALYSIS EXPERIMENT USING A MULTICHEMICAL ANALYSIS (MCA) SYSTEM Student Guidelines

I. Background References: 1. Harris, Daniel C. Quantitative Chemical Analysis, 5th Ed.; W.H. Freeman and Company: New York, 1999; pp 511-533 (Chapter 19).

2. Bare, W. D. Journal of Chemical Education, 2000, 77 (7), 929-933 3. Hansen, E. H.; Ruzicka, J. Journal of Chemical Education, 1979, 56 (10), 677.

Spectrophotometry When a molecule absorbs a photon of light, the energy of the molecule increases. The molecule has been promoted to an excited state (S1). If a molecule emits a photon, its energy is lowered. The lowest energy state of a molecule is called a ground state (So). The electrons of a molecule occupy the lowest energy molecular orbitals. When the appropriate amount of energy is introduced to the sample, some of the electrons are excited to higher energy molecular orbitals. This process is called absorption. Because a molecule cannot stay in an excited state indefinitely, the absorbed energy will be released. This process is called emission. In many cases, this energy is released in the form of infrared light or heat. In some cases, this energy is released as visible light or fluorescence. The amount of light absorbed or emitted can be measured and related to the concentration of the analyte of interest. When a molecule absorbs light of sufficient energy to cause an electronic transition, changes in the vibrational and rotational transitions happen as well [1].

Corpuscular-Probability Model

The Corpuscular-Probability Model [2] postulates that a solution contains absorbing bodies and non- absorbing bodies in random positions in the sample (Figure 1). The absorption of a photon is related to the probability of a photon being encountered by one of these absorbing bodies in solution. The probability of the photon being absorbed is also affected by the probability of it being transmitted. This model ignores both solvent effects and the probability that a photon can be absorbed more than once.

The following diagrams can be used as particulate level representations of the Corpuscular Model:

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Figure 1. Particulate representations of absorbance and emission of photons.

Figure 1 depicts molecules (or atoms) in solution. Letter A represents a non-absorbing body that will not absorb because it is a solvent molecule and/or because the photon might not cross the molecule’s cross section area of photon-capture. Letter A* represents an excited absorbing body that results in light attenuation (i.e. less light to be transmitted).

Figure 2. Cuvette and cuvette panels depicting photon absorption for concentrations 1C and 2C (top). Plots showing corresponding transmittance (It), and absorption (Ia) as a function of number of panels (bottom). Modified from Reference 2.

Figure 2 offers a visual representation of how light is absorbed and transmitted when the concentration of a solution doubles from 1C to 2C. The plots show how transmittance and absorbance changes as light travels through the cuvette. This depiction is slightly exaggerated to show that there is a more linear absorbance response (solid lines) for a concentration of 1C in comparison to 2C.

As part of the pre-lab assignment, you have been provided with a spreadsheet, to investigate the effects of changing each of these variables one at a time, i.e. either the concentration, molar absorptivity, or the path length. The resulting plots will depict the effect of each change on the transmittance line (It), on the left y- 144 axis and the absorbance line (Ia), on the right hand y-axis.

Beer-Lambert Law

In absorption based measurements, the measurement is usually taken at the wavelength of maximum absorbance, designated max . To find the wavelength of maximum absorbance, a spectrum (a plot of absorbance versus wavelength) for the compound of interest must be generated.

The Beer-Lambert Law states that the fraction of radiant energy transmitted through a solution (T) depends on the constant (a), the path length of the cell (b), and the concentration (c) of the chemical species:

-abc T = P/Po = 10 , or log T = log P/Po = -abc.

Where T = transmittance, P = power of transmitted radiation, and Po = power of incident radiation. The absorbance, A, is related to transmittance as follows: A = -log T = abc. (Note that absorbance is directly proportional to concentration and therefore is more useful than T for calculations) (Figure 3).

Figure 3. Schematic diagram of a single-beam spectrophotometer experiment (top). Representation of the relationship between transmittance and concentration (bottom). Modified from Reference 1.

In the equation, A = abc, the constant a is referred to as absorptivity which can be described as the probability that a molecule can absorb light. It depends upon both the wavelength of the incident radiation and the structure of the molecule. If b and c are held constant, absorbance then varies with wavelength in 145 direct proportion to a. The molar absorptivity (ε) has units of cm-1 mole-1 liter when b is given in cm and c in moles/liter [1]. Thus, A = εbc Flow injection Analysis (FIA)

The objective of FIA is to automate the acquisition of instrumental analysis measurements. Flow injection is based on the injection of a sample into a continuous carrier stream (Figure 4). The carrier stream is propelled by a pump (peristaltic or syringe); this stream provides the reagent to complex or react with the sample. The injection is executed with the use of a valve that will allow the carrier stream to carry the sample towards the detector. The carrier stream and the sample, once injected, will form a defined sample zone. The carrier reagent and the sample zone travel to the detector in a steady flow rate which defines the time needed for the reaction or the complexation to take place [3].

Figure 4. Schematic diagram of flow injection analysis.

II. Pre-lab Assignment:

1. Provide a justification for measuring salicylic acid in aspirin tablets. 2. Is the carrier stream acting as a reagent in this experiment? Provide a justification for its use in this experiment. 3. Identify one or two variables predicted by the Beer and Lambert Law equation that can influence the absorption of light by your solutions. 4. Identify one or two variables predicted by the corpuscular-probability model that can influence the absorption of light by your solutions. 5. Using the spreadsheet provided, what happens to the transmittance line when concentration of a compound is tripled?

Hazards: Iron nitrate is an oxidizer and nitric acid is a very corrosive acid; both should be handled with goggles, gloves and under a vent hood.

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Sodium salicylate might cause irritation to the respiratory tract. It should be handled with goggles and gloves.

III. Experiment

Besides being an important antagonist against pain, one 80 mg aspirin taken every other day slightly thins the blood and can reduce the risk of heart attack and stroke, particularly in men. Aspirin or acetylsalicylic acid (ASA) in tablets is slowly hydrolyzed by water in the air to salicylic acid (Figure 5).

O O OH OH O + H O + O 2 OH OH O

ce sa c c ac Salic lic Acid Acetic acid A tyl li yli id y

Figure 5. Acetylsalicylic acid (ASA) hydrolyzed by water.

Since acetic acid is somewhat volatile, the main impurity that remains is SA, which is very irritating to the stomach lining. Therefore, the Food and Drug Administration (FDA) has established a tolerance of 0.10% SA in unbuffered aspirin. Accidental salicylate poisoning from an overdose of aspirin can occur in children. Toxic effects can occur at higher than 300 mg/L (ppm) SA in blood plasma. Therefore, a clinical assay to monitor SA in serum is important.

In this colorimetric method, a purple complex is formed upon reaction of SA with ferric ion, and the absorbance of visible light by the complex can be measured (Figure 6). A calibration curve using standard SA solutions is generated and used to determine the original concentration of SA in an unknown. SA formed from the hydrolysis of an aspirin tablet in “stomach” acid will also be measured.

OH + 3+ + O + 2H3O + Fe H O O ( 2 )6 Fe(H2O)4 OH O

Salicylic acid Iron (III) salicylic acid complex ur e (p pl ) 147

Figure 6. Reaction of salicylic acid with iron complex to form a purple complex.

Reagents

1. Reagent solution/ carrier stream:

. o Dissolve 5 g of ferric nitrate, Fe(NO3)3 9H2O, in 500 mL of 0.1 M nitric acid.

2. Preparation of standard aspirin samples for calibration curve:

o Weigh out about 0.2619 gm (record exact weight) sodium salicylate (M.W. = 160) and dilute to 100 mL to prepare a 2,000 ppm (mg/L) salicylate stock solution. The molecular weight of sodium salicylate is 160 while that of salicylate is 137. Dilute the stock standard 50:50 with 0.01 M nitric acid to prepare a 200 ppm working standard.

o A calibration curve from 10-120 ppm (mg/L) containing at least 6 points is needed. Remember M1V1 = M2V2.

o Assume pipets from 1 to 10 mL are available. o Calculate different concentrations (M2) of solutions to be prepared in 50 mL (V2) volumetric flasks using volumes (V1) ranging from 1–20 mL of the 200 ppm working standard salicylate solution (M1). Please show your work.

MeasureNet Station set-up:

o Turn on the controller o Open MeasureNet icon on the computer. o Turn your station on, input your station number. o Select colorimeter experiments. o Select the optimum LED source (see below) if using MesureNet. o Select kinetics option. o Follow instructions to subtract signal from reference cuvette and flow cell.

Determination of LED source: The optimum LED is determined by the wavelength of maximum absorption in the spectrum (Figure 7) and the LED wavelength table (Table 1). Use the LED that best matches the λmax.

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Figure 7. UV-Vis of iron complex in FIA experiment.

LED Color Wavelength (nm) Peak Width* (nm)

Red 635 15

Green 515 30

Blue 470 25

* Peak width is the width of the light source emission peak at half the maximum absorbance value.

Table 1. LED wavelength table for MeasureNet.

Flow injection analysis (FIA) set up:

Figure 8. Set up diagram of FIA experiment 1. Pump with reagent solution or carrier stream, syringe containing sample to be injected, S (sample cuvette), R (reference cuvette), second syringe also contains reagent solution for reference cuvette. This is a set up that satisfies MeasureNet system. Vernier system 149 contains only one cuvette therefore subtracting the background of mobile phase should be done before taking each sample reading.

o Fill the syringe with purged reagent solution/ carrier stream. o Set desired flow rate. Record actual flow rate. o Fill the reference flow cell with reagent solution/ carrier stream. o Subtract the signal from reference flow cell in reference cuvette using the necessary steps requested in MeasureNet station.

o Arrange the standards in order of increasing concentration. Make sure all solutions are properly and clearly labeled.

o Allow 2 to 3 mL of solution reagent to flow through the cell. Practice injecting 1 mL of most diluted standard solution a couple of times or until you feel comfortable injecting. Check for reproducibility of results. It is suggested to allow a baseline of 30 seconds to show before making an injection.

o Inject the standard solutions one at a time, print and save results in your MeasureNet station.

Flow cell conditions:

o Flow rate: 1mL/min o Sample size: 1mL (inject after 30 seconds of flow) o Reference cuvette with reagent solution/ carrier stream

Sample Injection: Do at least duplicate measurements for all standards, control and unknown samples to ensure reproducibility.

Determination of salicylate in ‘ingested’ aspirin: Each group should do the following to prepare Control and Experimental aspirin samples:

Experimental Aspirin Sample:

o Grind an aspirin tablet (80 mg) until a fine and homogenous powder is obtained. This can be accomplished using a mortar and pestle. Record the weight in grams.

o Place the aspirin sample powder in a 50 mL beaker and add 10-20 mL (record volume) of 0.1 M HCl (simulated stomach acid). The acid concentration is suggested to be 0.1 M HCl, but you are free to choose a reasonable acid concentration to simulate stomach acid.

o Heat the sample in an oven for at least 30 - 60 min (record time) and measure final 150

temperature. Oven temperature can simulate stomach temperature ~37 degrees Celsius. Again you are free to simulate the body temperature of a healthy or feverish child. Record the temperature.

o Centrifuge the sample if necessary before injecting into FIA.

Control Aspirin sample:

o Grind a second aspirin tablet to fine powder using a mortar and pestle. Record the weight in grams.

o Place this control aspirin sample at room temperature in the same volume of water and heat for the same amount of time you heated the experimental aspirin sample. Water is used for the control aspirin sample instead of the acid used in the experimental aspirin sample.

o Centrifuge the sample if necessary before injecting into FIA.

Flow Injection of Experimental and Control aspirin samples: Suggested Sample size: 1mL

o Inject 1 mL volume sample of the control aspirin. Record actual sample size. o Inject 1 mL volume sample of the experimental aspirin. Record actual sample size. o Print and save results in your MeasureNet station.

Lab Calculations

1. Plot the results and determine the molar absorptivity from the linear least squares regression equation (slope value). The molecular weight (molar mass) of the Fe-salicylate complex is 263.8; use this to convert the slope value to Lmole-1cm-1. Turn in the plot and equation.

2. Determine the limit of detection (LOD) as the concentration corresponding to the [absolute value of the intercept (absorbance) of the linear least squares equation plus 3 times the fluctuation of the baseline for the blank)]/slope of the calibration curve.

3. Using the equation for your calibration curve, calculate the mg of SA formed in water at room temperature and at elevated temperature in acid. Be sure to consider the dilution factor at this point considering the original volume of solution used to dissolve the sample (10-20 mL). (For example, for the tablet in water, the dilution factor might be (20 mL tablet reaction solution)/(1 mL syringe injection). Show the calculations for mg salicylate formed by degradation of aspirin.

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4. Estimate the % formation of salicylate in the tablet as (moles SA formed) 100/ (moles ASA in tablet) for both samples. Clearly indicate type of aspirin, volume of acid, time, and temperature of reaction in the data section of your lab report.

IV. Post-Lab Assignment

1. What are three precautions that improve the reliability of spectrophotometric measurements?

2. Given the UV-Vis of bromophenol Blue dye (Figure 9) and Excel spreadsheet data “Bromophenolblue.Postlab”

a) Find the wavelength of maximum absorption. b) Using the Excel data provided title “Bromophenolblue.Postlab” create absorption versus concentration graphs for both the Green and Red LEDs.

Graph 1: Green LED: 500 nm, 515nm, 530 and (500 nm + 515 nm+ 530 nm) Graph 2: Red LED: 627nm, 635nm, 643 and (627 nm + 635 nm+ 643 nm)*

When an absorbance measurement is made with radiation composed of *multiple wavelengths the measured absorbance Am can be measure using equations below.

Example: Beam composed of two wavelengths: λ’ and λ”

A’= log (P’0/P’) = ε’bc

ε’bc P’0/ P’ = 10

And

-ε’bc P’ = P’010

Similarly for λ”

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-ε”bc P” = P”0 10

Am= log (P’0 + P”0) Substituting P’ and P” (P’ + P”)

-ε’bc -ε”bc Am= log (P’0 + P”0) – log (P0’10 + P0” 10 )

c) Choose the best LED (red or green) and explain your choice.

Figure 9. Polychromatic effect on Bromophenol Blue absorbance using Red and Green LEDs.

3. Describe at least two modern FIA instrumentations and a respective field application.

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Appendix A.2 Supplementary Materials FIA teacher FLOW INJECTION ANALYSIS EXPERIMENT USING A MULTICHEMICAL ANALYSIS (MCA) SYSTEM Teacher Guidelines

I. Pre-Lab assignment

The answers below assumed the student read the lab experiment background. The answers will vary if the student used external sources for their responses.

1. Provide a justification for measuring salicylic acid production in serum. Answer: Aspirin undergoes water hydrolysis producing salicylic acid, which is an irritant to the stomach lining. The pharmaceutical industry should measure production of salicylic acid both for quality control and for the expected shelf life of aspirin tablets. 2. Is the carrier stream acting as a reagent in this experiment? Provide a justification for its use in this experiment. Answer: Yes, the carrier stream is acting as a reagent. It is use to react with the salicylic acid to form an iron complex. This purple complex can be measured spectrophotometrically by absorbance of visible light. 3. Identify one or two variables predicted by the Beer and Lambert Law equation that can influence the absorption of light by your solutions. Answer: The student might answer: concentration of the solution, the molar absorptivity, the wavelength of incident light, distance the light has to travel (cuvette length) 4. Identify one or two variables predicted by the corpuscular-probability model that can influence the absorption of light by your solutions. Answer: The probability of the photon being absorbed can be affected by a non-absorbing body that will not absorb because it is a solvent molecule and/or because the photon might not cross the molecule’s cross section area of photon-capture. 5. Using the spreadsheet provided what happens to the transmittance profile when concentration of the compound is changed? Answer: The transmittance profile for the higher concentration decreases faster as a function of path length.

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Data set #1:

Width of one panel (mm) Number of panels Total path length (cm) Path lengh (b) 1 10 1 Concentration (mg/L) Molarity Concentration ( c) 50 0.000189538 1 (L/mol*cm) Compound MW 0.9 T1 Molar absortivity (a) 2000 Water 18 0.8 T2 Salycilate 263.8 0.7 Compound 2 0.6 Compound 3 0.5 0.4

Data set #2: Transmittance0.3 0.2 Width of one panel (mm) Number of panels Total path length (cm) 0.1 Path lengh (b) 1 10 1 0 Concentration (mg/L) Molarity 0 20 40 60 80 100 120 Concentration ( c) 150 0.000568613 Path Length (mm) (L/mol*cm) Compound MW Molar absortivity (a) 2000 Water 18 Salycilate 263.8 Compound 2 Compound 3 Figure 1. Student sample result using Excel spreadsheet.

II. Experiment

This experiment can be completed in a 3-hour laboratory period. Students can work in groups of 2 or 3 students.

Chemicals and reagents

. • Iron nitrate Fe (NO3)3 9H2O, nitric acid, sodium salicylate, all obtained from Sigma-Aldrich.

• 80 mg unbuffered aspirin tablets, found in the pain reliever section of a pharmacy. Colored and/or buffered tablets can affect absorbance results. Buffered aspirin tablets will raise the pH of the reaction, diminishing color formation.

• The reagent solution/ carrier stream should be pre-prepared and sonicated and/or purged with helium gas. Sonication/purging will eliminate air bubbles in the carrier stream, resulting in cleaner spectra. (A 300 mL volume of reagent solution can be purged for about 10 minutes of helium gas flow).

• Aspirin tables should be crushed to a fine, homogenous powder using a mortar and pestle.

• Use only one aspirin tablet for the control sample and one aspirin tablet for the experimental sample.

These reagents should be prepared before lab (see FIA student experiment).

Ferric nitrate in nitric acid carrier solution Stock solution of 2000 ppm salicylate in water 155

0.1 M HCl (for simulated stomach acid)

Materials needed for apparatus

FIA components

(1) Injection port: Hamilton Miniature inert Low Pressure valve: From Grace-Alltech, (2) 1mL sample syringe: Becton, Dickinson and Co. Ref # 309602. (3) Luer lock adapter (female luer to ¼, 28 male) for sample syringe: From Grace –Alltech. (4) Syringe pump with 50 mL gas tight syringe: from KD Scientific Pump Co. (5) MCA* detector

*Any MCA system that has a kinetic function and absorbance detector can be used, e.g. Vernier

Note: See LC teacher guidelines for photographs of the apparatus and how it is connected.

Tubing and Flow Cell

(1) Tubing*.

• 20 cm length, clear TeflonTubing: 1/16 in (1.6 mm ID x1/8” OD) (going in and out of a low- volume cuvette)

• 60 cm length, clear TYGONTubing: 3350 silicone 1/16 X 3/16 (0.0625 ID/ 0.1875 OD) (for other connections- to waste, injection, and pump)

* As a rule of thumb, band broadening is affected more by tubing diameter than length.

(2) Low volume cuvettes for MeasureNet sample and reference.

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1 2 3

Figure 2. Flow cell photos with different cuvettes. 1. A semi-micro VWR disposable cuvette K1948 PMMA 2. A ultra-micro Brand UV- disposable polystyrene cuvette from BrandTech 3. Semi-Micro Acrylic PMMA from VWR.

1. A semi-micro 2. A ultra-micro 3 A semi-micro PMMA cuvette polystyrene cuvette acrylic PMMA from VWR from BrandTech cuvette from VWR

Absorbance readings 0.794 0.299 0.980 MeasureNet

Fluorescence intensity 113.2 295.2 54 MeasureNet

Absorbance readings 0.552 0.546 1.688 Vernier

Fluorescence intensity 0.196 0.402 0.097 Vernier

Three different plastic cuvettes were tested: 1. Semi-micro VWR disposable cuvette K1948 PMMA, 2. Ultra-micro Brand UV- disposable polystyrene cuvette from Fisher Scientific and 3. Semi-Micro polystyrene (PS) from VWR. We recommend the used of cuvette 3 which gave us 3.3 times the absorbance in comparison to cuvette 2 and 1.2 times absorbance measurements in comparison to cuvette 1. For fluorescence measurements we recommend cuvette 2 that provided 5 times the intensity in comparison to cuvette 3. Cuvette 1 was used for all our measurements but it is no longer available for purchase. Semi-micro polystyrene or acrylic cuvettes will work for both experiments. The purpose of the semi-micro cuvette is to hold the flow cell tubing in place.

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Lab ware

Beakers of various sizes Pestle and mortar Scale Spatula D.I. water Oven Centrifuge Pipets of various sizes: 1mL, 2mL, 3mL, 5mL, 10 mL, 20mL to prepare salicylate calibration standards in 50 mL volumetrics.

Set-up conditions

• Flow rate: 1mL/min of carrier solution

• Injection sample: 1mL

• Inject sample after 30 seconds of run: It is important to inject after 30 seconds of mobile phase has passed through the flow cell to obtain a baseline.

• Wavelength of maximum absorbance: Green LED

• Reference cuvette contains mobile phase at all times

• Duplicate measurements for standards and aspirin samples should be taken to ensure reproducibility.

Determination of salicylate calibration curve See FIA student experiment.

Determination of salicylate in “digested” aspirin See FIA student experiment.

• The tablet should be ground to a powder. Actual mass should be recorded for more accurate concentration measurements.

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• The aspirin is suggested to be hydrolyzed in 0.1 M HCl (simulated stomach acid)

• The control aspirin sample at room temperature should be prepared at the beginning of experiment

• The experimental aspirin sample in the oven should be prepared at the beginning of experiment

• Centrifuging samples will allow to separate insoluble binder particles of the aspirin tablet, hence avoiding light scattering while measuring absorbance.

• Oven temperature used in our experiments was 40 °C and reaction time was 60 minutes.

• In our results, the absorbance for the experimental and control aspirin samples solutions could be increased by extending the time the sample rested at room temperature (control) or in the oven (experimental).

• Students can vary both the acid concentration for the experimental aspirin sample and/or the temperature:

Gastric acid: 0.1 M -0.01 M (pH~1 to 2)

Normal 36.5–37.5 °C (98–100 °F) Fever >37.5–38.3 °C (100–101 °F) Hyperthermia >38.4–39.9 °C (101–104 °F) Hyperpyrexia >40.0–41.5 °C (104–107 °F)

• Students should be encouraged to provide a reasonable justification for the chosen hydrochloric acid concentration and temperature. Higher temperature is recommended.

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Figure 3. Author’s FIA results in triplicate for 39 ppm (13.6 %RSD) salicylate standard. The injection is done within 60 seconds of running the mobile phase.

Figure 4. Author’s FIA results in triplicate for hydrolyzed aspirin sample (15.7% RSD).

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0.09 0.08 0.07 y = 0.00064x + 0.00180 0.06 R² = 0.99202 0.05 0.04

Absorbance 0.03 0.02 0.01 0 0 20 40 60 80 100 120 140 Concentration (ppm)

Figure 5. Author’s calibration curve for salicylate. Six data points are included in the calculation of the line equation. Each point in the graph represents the average of triplicate standard samples. The RSD range for all standards falls between 0.61 to 13.6%.

Lab Calculations

A = abc (page 6 in Student SI) y= (slope) x + intercept  slope = 6.4 x 10-4 = a x b [absorptivity (a) x cuvette path length (b)]

b= 2x (tubing of inner diameter) 6.4 x 10-3/ 0.32= a

a= 2.0 x 10-3

ε = (2.0 x 10-3L/ mg*cm)(1000mg/1g)(263.8 g/mol)=527

Notes:

• The value of ε found using FIA is quite a bit lower than using a regular cuvette where ε ~ 2000. This is due to the dilution factor of the sample during FIA.

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• FIA allows students to automate their manual sample injections without rinsing or changing cuvettes. The advantage of FIA is that it greatly reduces the time students spend taking data, especially if students want to check for reliability of results or do multiple runs of multiple standards.

• The instructor can choose between the manual standard cuvette method or the automated FIA approach. If both are executed, then students can analyze the advantages and disadvantages of each technique.

• A student calibration curve using the manual standard cuvette method is shown in Figure 6.

Figure 6. Student 1 calibration curve using manual standard cuvette method.

The fluctuation of the baseline for the blank can be measure from the baseline of a spectrum in absorbance units (Figure 7).

Answer.

LOD= |0.00180 + (3 * 0.3 x 10-5)| = 2.6 ppm 0.0007

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min= - 0.00411 max= - 0.00408

Figure 7. Fluctuation of absorbance baseline with time: |min-max|= 0.3x 10-5 in absorbance units.

Answer.

A control = 0.03635 Y = 0.00064 x + 0.0018

C control = 54 ppm. mg SA in 1 mL injection = 54 (0.001) = 0.054 mg SA in 13 mL original sample = 0.054(13/1) = 0.702 mg SA

Answer.

A unknown = 0.03891 Y = 0.00064 x + 0.0018

C unknown = 58 ppm

163 mg SA in 1 mL injection = 58(0.001) = 0.058 mg SA in 13 mL original sample = 0.058(13/1) = 0.754 mg SA

4. Estimate the % formation of salicylate in the tablet as (moles SA formed) 100/(moles ASA in tablet) for both samples. Answer. Control Aspirin sample = ( 0.702 mg SA/ 80 mg ASA)(180/138) *100 = 1.14 % Experimental Aspirin sample = (0.754 mg SA/ 80 mg ASA) (180/138)*100 = 1.23 % NOTE: Students can obtain different % salicylate conversion depending on reaction temperature and time.

III. Post-Lab Assignment

1. What are three precautions that improve the reliability of spectrophotometric measurements? Answer. (a) Stray light must be prevented from entering the spectrophotometer, because it leads to a false absorbance reading. The sample compartment must be light-tight. (b) Dust will scatter light and be read by the spectrophotometer as absorbance. Keep containers covered to prevent dust from entering. Cuvettes must also be free of fingerprints or other contamination. (c) Slight mismatch between sample and reference cuvettes, leads to systematic errors. The position of cuvettes in the spectrophotometer and/or turning the flat side of the cuvette by 180 degrees will affect reproducibility.

2. Given the visible absorbance spectrum of the bromophenol blue dye below (Figure 8).

Figure 8. Visible spectrum of bromophenol blue.

d) Find the wavelength of maximum absorption. Answer: 590 nm 164

e) Using the Excel data provided in the file titled “Bromophenolblue.Postlab”, create absorption versus concentration graphs for both the Green and Red LEDs (Figure 9).

Answer: Graph 1: Green LED: 500 nm, 515nm, 530 and (500 nm + 515 nm+ 530 nm) Graph 2: Red LED: 627nm, 635nm, 643 and (627 nm + 635 nm+ 643 nm)

Figure 9. Polychromatic effect on the absorbance of Bromophenol Blue using Red and Green LEDs. See Teacher Excel spreadsheet “Bromophenolblue.Teacher”. c) Which LED is recommended for use? Answer: Red LED because there is less variability in the molar absorptivities (slope of the lines)

3. Describe at least two modern FIA instrumentations and a respective field application. Answer: (1) FIAlab-2500 system http://www.flowinjection.com/5.%20Flow%20Injection.html Application: optimal for testing labs doing routine environmental/agricultural analysis, e.g., Nitrate, Phosphate and Ammonium assays. (2) FIA-SIA-LOV Sequential Injection Analysis System http://www.biocompare.com/22542-Sample- Injectors/142326-Micro-SIA-with-Lab-on-a-Valve-System/ Application: automate wet lab procedures by controlling assay parameters such as sample dilution, reagent/sample ratio and flow rate. Optimal for immunoassays, water quality analysis, dilution monitoring and chemical/biological monitoring.

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Appendix A.3 Supplementary Materials LC student Liquid Chromatography Experiment

Student Guidelines

I. Background

Reference:

[1] Miller, James M. Chromatography: Concepts and Contrasts, 2nd Ed.; Wiley-Interscience: 2005; pp 41-51.

Liquid Chromatography

Separation methods employ two phases: the mobile phase (MP) and the stationary phase (SP). As the mobile phase passes over and through the stationary phase, the components of the mixture are retarded in their passage through the system in proportion to their interaction with the stationary phase (and repulsion from the mobile phase), resulting in different migration rates. At a given time an analyte molecule is either in the mobile phase, moving along at its velocity or in the stationary phase not moving at all. Generally if the sample is attracted towards the stationary phase the process is called adsorption, alternatively if the sample diffuses in and out of the interior of the stationary phase the process is called partition [1].

A separation is effective if the various components emerge or elute from the column at different times; these times are called retention times (t). Figure 1 below depicts the status of the separation at five different times or snapshots of separation [1].

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Figure 1. Schematic representation of the chromatographic process, modified and reprinted with permission (Reference 1)

Flow: The mobile phase flows from left to right carries the mixture along the bed (length 0-1). Most chromatographs are operated with a constant flow rate symbolized by (F).

1st (top) snapshot of the separation: The mixture of analytes A and B are introduced in the bed ideally in as narrow a zone as possible.

2nd and 3rd snapshots: Analyte A has a greater affinity for the mobile phase. It spends more time in the mobile phase (see concentration of solute in mobile phase, upper peak on the bed, in comparison of the concentration of analyte A in the stationary phase, lower peak on the bed). Therefore analyte A travels faster than analyte B.

4th snapshot: Analyte A is eluted faster than analyte B. At this point analyte A is seen in the detector window.

5th snapshot: This represents a complete elution of the analyte B. The chromatogram is generally a plot of detector signal (absorbance units or fluorescence intensity for example) versus time, as represented in the far right side of the figure.

The chromatogram in this schematic representation shows two resolved peaks. This is the “ideal” chromatogram. If peak overlap occurs the composition of the mobile phase should be changed, depending on the type of stationary phase. See appropriate chapter on liquid chromatography in your textbook.

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Reversed Phase Chromatography

Compound polarity is a measure of how equally bonding electrons are shared between atoms in the structure. If unequal sharing of electrons occurs then we can say that the compound is polar. Table 1 below shows structures of non-polar and polar compounds.

Table 1. Examples of polar and non-polar substances. Where R=Aliphatic hydrocarbon.

Non-Polar

R-CH3

Methyl

Non-Polar R

Phenyl

Non-Polar O

R CH3 Carbonyl

Polar

R-CH2-OH Hydroxyl

Polar

R-CH2-SH Sulfhydryl

Polar

R-COOH Carboxyl

Polar

Amino R-NH2

Reversed phase chromatography is a separation technique that uses a non-polar stationary phase and a polar mobile phase. It is considered to be a partition separation. In Figure 2, the stationary non-polar 168 phase like C-18 is bonded to the column. A mixture of analytes is separated based on the polarity of each constituent. For example, a more non-polar compound will be attracted to the stationary phase and a more polar compound will be attracted towards the mobile phase. Figure 2 depicts the mobile phase components, solvent A and solvent B. Solvent A is the weak eluting solvent water and B is the strong eluting solvent such as methanol or acetonitrile. The chromatographer can manipulate or change the percentages of each solvent the makes up the mobile phase to improve resolution of analyte peaks. Figure 2 also shows that the most polar compounds will elute first and the most non-polar compounds elute last.

Figure 2. Reversed phase chromatography

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II. Pre- Lab

1. Let’s assume that you did a reversed phase separation of this mixture of compounds.

HOOC H3C COOH

NH2

Predict the elution order: ______

2. What are the components of the mobile phase you will use to separate the dyes in class?

3. What mobile phase component should be increased in volume percent to provide longer in time analyte retention and why?

4. Given the chemical structures of riboflavin and fluorescein. Predict the elution order of the dyes in a reverse phase separation, justify your answer.

Riboflavin Fluorescein

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III. Experiment

Objective: Separation of a mixture of similar colored organic compounds using a reversed phase separation.

Materials:

• MeasureNet • Deionized water • HPLC graded methanol • Riboflavin (Vitamin B2) Sigma • Fluorescein, sodium salt. Aldrich • Various 50 mL beakers • 1 mL syringe • T-valve • Flow cell- See plastic cuvette comparisons in FIA teacher’s guidelines • A clamp • An syringe pump or a peristaltic pump • Helium gas source for purging or degasser

Set-up:

Use the diagrams (Figures 3 and 4) and photographs (Figures 5, 6, 7) below to set-up the liquid chromatography (LC) instrument.

Figure 3. Schematic diagram of LC set up.

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Figure 4. Set up diagram of LC Experiment. Pump with mobile phase (MP), syringe containing sample to be injected, SPE column (C-18 cartridge), S (sample cuvette), R (reference cuvette), second syringe also contains MP for reference cuvette.

Hazards:

Riboflavin and fluorescein: May be hazardous in case of ingestion. Immediately flush eyes with running water for at least 15 minutes, keeping eyelids open. After contact with skin, wash immediately with plenty of water.

Methanol: May be fatal or cause blindness if swallowed. Vapor harmful. Flammable liquid and vapor. Harmful if swallowed, inhaled, or absorbed through the skin. Causes eye, skin, and respiratory tract irritation.

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Student station

Injection port

Column

Flow cell Pump

Figure 5. Liquid chromatograph

Injection port, t- valve and syringe

Figure 6. Colorimeter Figure 7. Injection site

Procedure:

Preparation of solutions:

• Riboflavin 10-4 M. Riboflavin is slightly soluble in water. If not homogenous solution is achieved then allow solution to stir with a magnetic stirrer for 30 minutes or until a clear solution is seen.

• Fluorescein 10-3 M. Fluorescein is slightly soluble in water, but it forms a clear solution.

Preparation of Mobile phase:

• Mobile phase composition is 60 percent water and 40 percent methanol. • Purge about 300 mL of mobile phase with helium gas for 10 minutes.

Flow rate: Set a flow rate to 1mL per minute.

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Column conditioning:

• For new column: o wash column with 2 mL of 100 percent methanol o wash column with 10 ml of mobile phase

• For used column: o Run at least 5 mL of mobile phase to condition column, before injecting a new sample.

Sample injection:

• Practice injecting mobile phase manually at a constant speed, to avoid back pressure

• Sample size: 0.2 mL.

Procedure using absorbance detector:

• Set-up MeasureNet for absorbance readings using the colorimeter LED: Blue

• Subtract reference background using only mobile phase while using absorbance detector MeasureNet. • Time: Min: 0 seconds Max: 1500 seconds (Fluorescein); 600 seconds (Riboflavin) • Absorbance (y-axis) Min: 0 Max: 1.5. • Inject sample 0.2 mL of one of the solutions and start the run in student station. • Run each sample in duplicate, using the optimum condition analysis. • Do column conditioning if necessary to avoid contamination. • Save results and print spectrum • Inject a 0.2 ml sample of 2:1 mixture 10-4 M Riboflavin and 10-3 M Fluorescein respectively. • Run mixture in duplicate, using the optimum condition analysis. • Do column conditioning if necessary to avoid contamination • Save and print chromatogram

Procedure using fluorimeter:

• Set-up MeasureNet for fluorescence intensity readings using the proper LED. • Only one sample cell cuvette is use during fluorescent intensity measurements • Time: Min: 0 seconds Max: 1500 seconds (Fluorescein); 600 seconds (Riboflavin) • Fluorescence Intensity : y-axis min: 0 y-axis max: 20 • Inject sample 0.2 mL of one of the solutions and start the run in student station. 174

• Run each sample in duplicate, using the recommended condition analysis. • Do column conditioning if necessary to avoid contamination • Save data and print spectrum • Label and find retention time (t) for each dye in spectrum • Inject a 0.2 ml sample of 2:1 mixture 10-4 M Riboflavin and 10-3 M Fluorescein respectively. • Run mixture in duplicate, using the optimum condition analysis. • Do column conditioning after every run, to avoid contamination • Save and print chromatogram

Mobile phase composition:

• Third of the class: Increase the methanol content by 20% in the mobile phase, condition the column, and rerun the chromatogram. • Third of the class: Increase the water content by 20% in the mobile phase, condition the column, and rerun the chromatogram. • Third of the class: Increase methanol to 100 % in the mobile phase, condition column, and rerun the chromatogram. • Exchange copies of chromatograms.

IV. Post-Lab

Analysis of Chromatograms:

Your chromatogram will likely show an eluted peak very early in the run as represented schematically in Figure 8. This peak is due to the solvent front, the refractive index mismatch of sample solvent and mobile phase. It is an unretained peak and it is symbolize by tM. To fix the difference between the retention time (t) of the analyte and the unretained peak (tM), we can calculate the retention factor (k’) k’ = (t -tM) / tM where t is the retention time of the dye and tM is the unretained peak.

The resolution of peaks can also be calculated as α (column selectivity).

α=k’2/k’1 where k’2= retention factor for peak 2

and k’1 = retention factor for peak 1

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Figure 8. Representation of tM and t.

1. Label and find retention times (t) and retention factors (k’) for each dye in the data file obtained with absorbance detector.

Use the following equations:

k’1=t- tM / tM tM = t′M

k′2=t′- t′M / t′M

2. Find the selectivity factor of the column(s) using the equation provided below

α=k’2/ k’1 where k’2= retention factor for peak 2

and k’1 = retention factor for peak 1

3. Discuss the change in retention time and α as a function of methanol content in the mobile phase.

4. Compare and explain the relative peak height of riboflavin to fluorescein using the (1) absorbance detector and (2) fluorimeter under the same chromatographic (column and mobile phase) conditions.

5. Describe at least two modern HPLC instrumentations and a respective field application.

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Appendix A.4 Supplementary Materials LC Teacher Liquid Chromatography Experiment

Teacher Guidelines

Pre- Lab

1. Let’s assume that you did a reversed separation of this mixture of compounds.

HOOC H3C COOH

NH2 Predict the elution order: ______

Answer:

COOH HOOC H3C

NH2

2. What are the components of the mobile phase you will use to separate the dyes in class? Answer: Water and methanol

3. What mobile phase component should be increased in volume percent to provide longer in time analyte retention and why?

Answer: The volume percent of methanol in the mobile phase should be increased because it is the less polar component of the mobile phase.

4. Given the chemical structures of riboflavin and fluorescein. Predict the elution order of the dyes in a reverse phase separation, justify your answer.

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Riboflavin Fluorescein

Answer: Riboflavin with multiple OH and N groups is more polar than fluorescein therefore riboflavin will elute before fluorescein.

Timeline: This is a 3-hour experiment.

Liquid chromatograph

The following pictures are provided in case the instructor would like the student to build the flow cell and complete the LC set-up.

Student station

Injection port

Column

Flow cell Pump .

Figure 1. Liquid chromatograph

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Flow cell

Injection port Goes to Sample waste cuvette Waste container container for reference cuvette

Reference cuvette Black felt cover

Figure 2. Reference and sample cuvettes Figure 3. Different view of column

The reference flow cell on the left (R) is filled with the mobile phase using a syringe. The sample flow cell on the right (S) will monitor the mobile phase with the sample components which end up in the waste container.

Injection port, t-valve and syringe

Figure 4. Left: colorimeter is cover with black felt to avoid light exposure. Middle: pump. Right: injection site

Materials:

• MeasureNet* • Deionized water • HPLC grade methanol • Riboflavin (Vitamin B2) Sigma • Fluorescein, sodium salt. Aldrich • Various 50 mL beakers 179

• Black felt dimensions: 50cm x 20 cm • 1 mL syringe • Tubing: 40 cm of clear Teflon Tubing: 1/16 X 1/8 (0.0625 ID/ 0.125 OD)

1 m of Silicone Tubing: 1/16 X 3/16 (0.0625 ID/ 0.1875 OD)

• T-valve: Hamilton miniature inert low pressure valve, purchased from Grace-Alltech. • A syringe pump such as that from KD Scientific Pump Co. A peristaltic pump may also work. • Helium gas source for purging and/or sonicator • Low volume cuvette polystyrene or methacrylate from Fisher brand. UV/Vis (285 to 750nm)

*Any MCA system that has a kinetic function and absorbance detector and/or fluorimeter can be used, e.g. Vernier.

Columns:

Prevail C-18 SPE column was purchased from Grace (Alltech)

• Base structure: 50 µm irregular silica, 60 A • Carbon Loading: 11%, end capping ∘ • Column size: 4.0 mL, 900 mg bed weight

Maxi-Clean® column was purchased from Grace (Alltech):

• Base structure: 50 µm silica, 60 A • Carbon Loading: 6%, end capping∘ • Column size: 4.0 mL, 900 mg bed weight

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MeasureNet system:

Figure 5. Measurenet network, controller, and station. Reprinted with permission of Measurenet

Experiment

Preparation of solutions:

• Riboflavin 10-4 M. Riboflavin is slightly soluble in water. If not homogenous solution is achieved then allow solution to stir with a magnetic stirrer for 30 minutes.

• Fluorescein 10-3 M. Fluorescein is slightly soluble in water.

• 2:1 mixture 10-4 M Riboflavin and 10-3 M Fluorescein is the sample.

Optimum conditions analysis:

• Mobile phase composition is 60 percent water and 40 percent methanol. • Purge about 300 mL of mobile phase with Helium gas for 10 minutes. This purging step is important. It serves as a degassing step. Air bubbles will cause air spikes in the chromatogram. • Flow rate: 1mL per minute

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Column conditioning:

• For new column: o wash column with 2 mL of 100 percent methanol o wash column with 10 ml of mobile phase

• For used column: o Run at least 5 mL of mobile phase to condition column, before injecting a new sample.

Sample injection:

• Practicing injection of the mobile phase is important for students to avoid back pressure. The key is to manually inject at a constant speed. Sample size: 0.2 mL

Procedure using MeasureNet absorbance detector:

• Set-up MeasureNet for absorbance readings using the colorimeter LED: Blue

• Subtract reference background using only mobile phase while using absorbance detector MeasureNet • Time: Min: 0 seconds Max: 1500 seconds (Fluorescein); 600 seconds (Riboflavin) • Absorbance (y-axis) Min: 0 Max: 1.5 • Inject sample 0.2 mL of one of the solutions and start the run in student station. • Run each sample* in duplicate, using the optimum condition analysis.

* This step is important for students, so they know the retention times for each compound, at this point they can go back and check the prediction they did in pre-lab question 4.

Procedure using MeasureNet fluorimeter:

• Set-up MeasureNet for Fluorescense intensity readings using the fluoremeter • Only one sample cell cuvette is use during fluorescent intensity measurements • Time: Min: 0 seconds Max: 1500 seconds (Fluorescein); 600 seconds (Riboflavin) • Fluorescence Intensity : y-axis min: 0 y-axis max: 20 • Inject sample 0.2 mL of one of the solutions and start the run in student station.

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Author (AVM) sample chromatograms using absorbance mode in MeasureNet and Vernier:

Below are triplicates runs of each dye (Figures 6, 7) and dye mixtures (Figures 8, 9)

Figure 6. Riboflavin elution in MeasureNet system. Maxiclean® SPE cartridge; 60:40 water:methanol mobile phase. 1ml/min flow rate. 0.2mL sample injection.

Figure 7. Fluorescein elution in MeasureNet system. Maxiclean® SPE cartridge; 60:40 water:methanol mobile phase. 1ml/min flow rate. 0.4 mL sample injection.

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Figure 8. Separation of a mixture of Riboflavin and Fluorescein using a colorimeter in the MeasureNet system. Prevail® SPE cartridge; 60:40 water:methanol mobile phase. 1ml/min flow rate. 0.2 mL sample injection.

Figure 9. Separation of a mixture of Riboflavin and Fluorescein using the absorbance mode, in Vernier system Maxiclean® SPE cartridge; 60:40 water:methanol mobile phase. 1ml/min flow rate. 0.2 mL sample injection.

Author (AVM) sample chromatograms results using a fluorimeter in MeasureNet and Vernier:

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Below are triplicates runs of each dye (Figures 10, 11) and dye mixtures (Figures 12, 13)

Figure 10. Riboflavin elution in MeasureNet system. Maxiclean® SPE cartridge; 60:40 water:methanol mobile phase. 1ml/min flow rate. 0.4 mL sample injection.

Figure 11. Fluorescein elution in MeasureNet system. Maxiclean® SPE cartridge; 60:40 water:methanol mobile phase. 1ml/min flow rate. 0.4 mL sample injection.

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Figure 12. Separation of a mixture of Riboflavin and Fluorescein using a fluorimeter in MeasureNet system. Maxiclean® SPE cartridge; 60:40 water:methanol mobile phase. 1ml/min flow rate. 0.2 mL sample injection.

Figure 13. Separation of a mixture of Riboflavin and Fluorescein using a fluorimeter in Vernier system. Maxiclean® SPE cartridge; 60:40 water:methanol mobile phase. 1ml/min flow rate. 0.4 mL sample injection.

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Student sample chromatograms for mixture separation in MCA system:

Below are runs of dye mixtures (0.2 mL injections) using MeasureNet (Figures 14, 15) and using Vernier (Figure 16)

Figure 14. Separation of mixture using MeasureNet colorimeter. PREVAIL® SPE cartridge; 60:40 water:methanol mobile phase. 1ml/min flow rate.

Figure 15. Separation of mixture using MeasureNet fluorimeter. PREVAIL® SPE cartridge; 60:40 water:methanol mobile phase. 1ml/min flow rate.

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Figure 16. Student’s separation of a 2:1 mixture of riboflavin and fluorescein using the Vernier- SpectroVis Plus detector in the absorbance mode and the Maxi-cleanTM SPE cartridge. 60:40 water:methanol; 1 mL/min.

Optimization of mobile phase

When the column is being cleaned with 100 % methanol, students could make a sample injection of the mobile phase. Only one unretained peak will be evident indicating no separation. A mobile phase of 20 % water 80 % methanol could be used to reduce the analysis time using the Prevail column which actually shows excessive peak resolution (Figure 14).

Post-Lab

Analysis of Chromatograms:

1. Label and find retention times (t) and retention factors (k’) for each dye in spectrum using the equations provided below

k’1=t- tM / tM tM = t′M

k′2=t′- t′M / t′M

2. Find the selectivity factor of the column using the equation provided below

α=k’2/ k’1 where k’2= retention factor for peak 2

and k’1 = retention factor for peak 1

Answer: These data are found in Table 2 of manuscript.

3. Discuss the change in retention time and  as a functio 188

Answer: As the methanol content in the mobile phase increases, the retention factor k’ decreases. Using 100 % methanol in the mobile phase, the components are unretained (one peak). The log k’ versus % methanol is a linear relationship.

4. Compare the relative peak height of riboflavin to fluorescein using the 1. absorbance detector and 2. fluorimeter under the initial chromatographic conditions.

Answer: Considering the concentration of riboflavin is a factor of 20 less than that of fluorescein, both the absorbance and fluorescence of riboflavin are markedly stronger than that for fluorescein.

5. Describe at least two modern HPLC instrumentations and a respective field application. Answer:

1) Alliance® HPLC System by Waters application: Forensics http://www.waters.com/webassets/other/lp/sem_hplc.html?xcid=183_20111107

2) Flexar UHPLC systems by Perkin Elmer. Application: Food safety (formulations), pesticide traces or residues, forensics. http://www.perkinelmer.com/catalog/category/id/liquid%20chromatography%20hplc%20and%20uhplc

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Trouble shooting section

What to do when I have:

Peak shape changes Solution

Possible cause (1) Change column

(1) Sample interacting with active sites in silica column. Cartridge column bed has voids and/or defects.

Large unretained peak Solution

Possible cause (1) Prepare sample using the mobile phase as the solvent. (1) Sample solvent incompatible with mobile phase

All peaks are too small Solution

Possible cause (1) Use larger sample loop

(1) Injection size too small

All Peaks are too large Solution

Possible cause (1) Use smaller sample size

(1) Injection size too large

Retention time drifts Solution (s)

Possible cause(s) (1) Practice injecting constant sample injections, multiple times (1) Manual injection varies (2) Prevent change due to evaporation of MP by (2) Mobile phase changing covering MP

(3) Poor column equilibration (3) Allow more time for column equilibration between runs (4) Flow rate change (4) Reset flow rate (5) Air bubble in pump (5) Purge mobile phase longer and/or run more mobile phase to get rid of bubbles

Baseline noise Solution(s)

Possible cause (1) Check system for loose fittings (1) Check pump for leaks, unusual noises (1) Leak (s) (1) Change pump seals if necessary

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Appendix A.5

Permission to use MeasureNet Website Pictures

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Appendix A.6

Permission to use book’s diagram

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Appendix B

Flame Test demonstration

A) Materials:

1. Lithium Chloride powder 2. Copper chloride powder 3. Sodium Chloride powder 4. Wooden coffee stirrers 5. Cups with water (2) 6. A Bunsen burner 7. Methane gas

NOTE: Prior to starting the experiment, students will be asked to put on a pair of splash-proof goggles to protect their eyes. In addition, students will be provided gloves to wear if they so desire.

B) Procedure

1. Some wooden coffee stirrers will soaking in a cup of water 2. Take one wet coffee stirrer and dip it into copper chloride powder (green powder) 3. Then put the green powder under the flame of the Bunsen burner 4. Observe the color of the flame and dispose the wooden stirrer into the second cup of water labeled “waste” 5. Repeat steps 2,3, and 4 with lithium Chloride and Sodium chloride powders (white color powders)

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Appendix C

IRB 1st approval

Office for the Advancement of Research and Scholarship 102 Roudebush Hall Oxford, OH 45011

513-529-3600

Date: November 5, 2010

To: Ms. Ana Vasquez Murata, Chemistry & Biochemistry Dr. Stacey Lowery Bretz, Chemistry & Biochemistry

From: Dr. Leonard S. Mark, Chair Institutional Review Board for Human Subjects Research

Re: Human Subjects Project: Student Conceptions of Emission

Your proposed revisions / modifications to the above-referenced protocol was reviewed and approved by the Institutional Review Board for Human Subjects Research.

Your proposal approval number is: 09-457

Approval of this project is in effect until: March 14, 2011

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If you complete your project before the date listed above, please send an email to [email protected] that your project is complete.

Should you decide to change your procedures relating to the use of human subjects in the above project, you must obtain approval from the Committee prior to instituting any changes.

Miami University policy requires periodic review of human subjects for all ongoing projects. If your project will continue beyond the approval date mentioned above, you will need to submit an Application for Continuing Review so that the committee may review your application in a timely fashion.

Please submit your next application for continuing review after: February 12, 2011

On behalf of the committee and the University, I thank you for your efforts to conduct your research in compliance with the federal regulation that have been established for the protection of human subjects. Thank you for your attention to this matter, and best wishes for the success of your project.

09-457

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Appendix D

IRB 2nd Approval

Office for the Advancement of Research and Scholarship 102 Roudebush Hall Oxford, OH 45011 513-529-3600

March 11, 2011

To: Ms. Ana Vasquez Murata, Chemistry & Biochemistry

Dr. Stacey Lowery Bretz, Chemistry & Biochemistry

From: Dr. Leonard S. Mark, Chair Institutional Review Board for Human Subjects Research

Re: Human Subjects Project: Student Conceptions of Emission

Thank you for submitting the above-referenced application for approval of a continuing project. Your proposal has been reviewed and approved by the Institutional Review Board for Human Subjects Research.

Your proposal approval number is: 11-105

Approval of this project is in effect until: March 13, 2012

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Appendix E

Student Informed Consent Form

The purpose of this research study is to better understand how students think about chemistry. Before agreeing to participate in this research, please be sure to thoroughly read this consent form. If you have any questions or concerns, please contact Dr. Stacey Lowery Bretz, at [email protected]. If you have any questions about your rights as human subjects please contact the office for the advancement of Research and Scholarship (513-529-3600) or [email protected]

I agree to participate in this research study regarding what students know about chemistry. Though my professor may know whether I participate, s/he will not be able to match my name to the responses I have given. The information I provide may be used for additional research or publications; however, since my name is not used, my identity in this study is protected. I have had the opportunity to ask any questions I might have about my participation in this study and they have been answered to my satisfaction. By signing my name below, I certify that I have read the consent form, agree to participate in this study and I confirm that I am at least 18 years of age.

______

Signature Date

______

Printed Name

1. I would best describe myself as (check only one):

____ Freshman ____Sophomore ____ Junior ____ Senior ___Graduate Student

2. What is your gender?

____ Male____ Female

3. What is your race/ethnicity?

____ African American/Black ____ American Indian/Alaska Native ____ Asian/Pacific Islander ____ Hispanic ____ Caucasian/White ____ Other (please specify): ______

4. What is your major? ______

5. Would you be willing to take part in an interview that will last approximately 20 minutes at a mutually convenient time during this semester? During the interview your responses will be audio recorded. Your participation in the interview is completely voluntary and will in no way affect your grade in any chemistry course. Depending on the number of students who volunteer for the interview, it may not be possible to interview all volunteers, in which case a sample will be chosen. If you are willing to participate in the interview, please fill in your email address.

E-mail address: ______

If you do not wish to participate in the interview, please leave your email address blank.

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Appendix F High School Principal Consent

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Appendix G Parent Consent Form There are two copies of the Consent Form (one for you to return to your child’s teacher and one for you to keep). Please return the bottom of this Consent Form by May #.

I understand the research study described by Dr. Bretz and have been given a copy of the description of this research. I understand that my son/daughter will be asked to provide verbal assent to participate in this research and may discontinue the research at any time without consequence. I am aware that the interviews will be video and audio taped and that my child will not be identified in any recordings used in presentations and discussions of this research. I agree to allow my son/daughter to volunteer to participate in this research.

______

Name of Student (please print)

______

Name of Parent/Guardian (please print)

Relationship to student (circle one)

Mother / Father / Guardian / Other

______

Signature of Parent/Guardian

______

Date

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Appendix H

Informed assent script for minor student participant

Hi [Student’s Name],

Thank you for volunteering to participate in my research. My name is Ana Vasquez Murata, and I go to school at Miami University. I am interested in high school students’ ideas about chemistry and that is why I want to talk with you. Your [mom/dad/guardian] has given you permission to talk to me. I am going to ask you some questions before we begin to make sure you understand what you are agreeing to and to make sure you understand the interview process.

To start, I have brought with me this tape recorder and this video camera to record our interview. If it is ok with you, I’d like to turn them on and place them over here on the table. [Indicate a spot out of the way, but still close enough to catch the conversation.] Can I turn on the recorders? [If yes, turn on the recorder.] Do you agree to allow me to record our discussions? Do you understand that you may ask me to turn off the recorder at any time and that I will turn it off without asking any questions?

[If assent is not given and the student wishes to stop the interview:] That’s ok. We can stop the interview here. I am glad I got to meet you and I thank you for showing interest in my research. Let’s go back to class.

[If assent is given:] Ok, good. Next I want to tell you that I am interested in YOUR ideas. The questions I have are meant to start a discussion between us so that I can learn about your ideas. If you do not understand a question, you should tell me and ask me to ask the question in another way. Also, if you do not want to answer a question, you can tell me and I will move on to the next question. Do you understand that you can ask me any questions at any time and that you do not have to answer any question that you do not want to answer?

[If assent is not given and the student wishes to stop the interview:] That’s ok. We can stop here. I am glad I got to meet you and I thank you for showing interest in my research. Let’s go back to class.

[If assent is given:] Ok, good. Lastly, I will not use your name when I discuss my research. Do you understand that no one will be able to know what YOU specifically told me? Even your teacher won’t know, so he/she can’t hurt or improve your grade. Do you agree to continue to participate in this research?

[If assent is not given:] That’s ok. It was nice meeting you and I thank you for showing interest in my research. Let’s go back to class.

[If assent is given:] Ok, great. Now let’s get started.

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Appendix I

Exempt from Undergraduate IRB Review

Research Compliance Program 102 Roudebush Hall Miami University Oxford, Ohio 45056

Certification: Human Subjects Research Exempt from IRB Review 18 Aug 11 Exempt Research Certificate Number:00349 To: Dr. Stacey Lowery Bretz RE: Umbrella Protocol: Bretz Laboratory Undergraduate Chemistry Surveys The project noted above and as described in your application for registering Human Subjects (HS) research has been screened to determine if it is regulated research or meets the criteria of one of the categories of research that can be exempt from Institutional Review Board review (per 45 CFR 46). The determination for your research is indicated below.

The research described in the application is regulated human subjects research, however, the description meets the criteria of at least one exempt category included in 45 CFR 46 and associated guidance.

The Applicable Exempt Category(ies) is/are: 2

Research may proceed upon receipt of this certification. When research is deemed exempt from IRB review, it is the responsibility of the researcher listed above to ensure that all future persons not listed on the filed application who i) will aid in collecting data or, ii) will have access to data with subject identifying information, meet the training requirements (CITI Online Training).

If you are considering any changes in this research that may alter the level of risk or wish to include a vulnerable population (e.g. subjects <18 years of age) that was not previously specified in the application, you must consult the Research Compliance Office before implementing these changes.

Exemption certification is not transferrable; this certificate only applies to the researcher specified above. All research exempted from IRB review is subject to post-certification monitoring and audit by the compliance office.

Neal H. Sullivan, Research Compliance Officer Notes: This exemption combines previously IRB approved protocols 10-090 and 11-026. The activities involved with both projects qualify for exemption . As an umbrella protocol and qualifying for exemption, unless procedures, personnel, or subjects change in a way that effects risk or disqualifies this project from exemption, minor changes may be made without Compliance Office approval.

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Appendix J

Exempt from High school IRB Review

Research Compliance Program 102 Roudebush Hall Miami University Oxford, Ohio 45056

Certification: Human Subjects Research Exempt from IRB Review

6-Apr-12 Exempt Research Certificate Number: To: Dr. Stacey Lowery Bretz Neal H. Sullivan, E00532 Research Bretz High School Chemistry Surveys RE: Compliance

Officer The project noted above and as described in your application for registering Human Subjects (HS) research has been screened to determine if it is regulated research or meets the criteria of one of the categories of research that can be exempt from Institutional Review Board review (per 45 CFR 46). The determination for your research is indicated below.

The Applicable Exempt Category(ies) is/are: 1, 2 Research may proceed upon receipt of this certification. When research is deemed exempt from IRB review, it is the responsibility of the researcher listed above to ensure that all future persons not listed on the filed application who i) will aid in collecting data or, ii) will have access to data with subject identifying information, meet the training requirements (CITI Online Training).

Exemption certification is not transferrable; this certificate only applies to the researcher specified above. All research exempted from IRB review is subject to post- certification monitoring and audit by the compliance office.

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Appendix K

Interview Guide

Please speak slowly and clearly. Take as much time as you need, do not rush

Phase one: SAY: Scientists know that atoms can absorb and release energy, but what I would like to talk to you about today is specifically about the release of that energy. 1) What can you tell me about how atoms release energy? If they do not have anything to say then say: 2) Tell me anything that might be related to how atoms release of energy 3) In what forms of energy atoms release energy? You may use this paper and pen to annotate or draw diagrams about what you know about how atoms release energy.

Phase Two: First Prompt: Flame test Code for type of question (P) Predicting (O) Observing (E) Explaining All students will be interview in a chemical laboratory hence they will be provided goggles and gloves for safety. SAY: Because we are in a laboratory and there is always a chance that something could splash, I am going to ask you to put these goggles and gloves on and I’ll put them on too. Here is the set up for an experiment known as “flame test”. First you will read the procedure for what we are about to do (Have materials available for Flame test)

Questions for copper chloride (green powder) 4) (P) What do you think is going to happen when you hold this green powder in the flame? 5) (P) What do you expect to see when you hold this green powder in the flame? SAY: Now can you please run the flame test for the green powder of copper chloride

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[CuCl2 (green powder)-emits green color flame] 6) (O) Can you please describe what you see in this experiment 7) (E) Can you explain what happened? 8) (E) Can you explain what happens to the elements in the flame? Questions for LiCl and NaCl (white powders) SAY: We will do the flame test with these two other substances (show the student the white powders) 9) (P) Now, What do you think is going to happen when you hold each of these two powders (point at the two white powders) in the flame? 10) (P) What do you expect to see when you hold each of these two powders in the flame? SAY: Now can you please run the flame test for these two white powders named Lithium chloride and sodium chloride LiCl (white powder)-emits red color flame NaCl (white powder)-emits orange color flame 11) (O) Can you please describe what you see in this experiment 12) (E) Can you explain what happens to the elements in the flame? 13) (E) And why are these two white powders give out different color flames then? 14) (E) Can you explain why these white powders give out different color flames in comparison to the green powder given out a green color flame? 15) (E) what determines the color of flame you see in the flame test? SAY: Following up with the colors you saw earlier you said that what you saw a green flame and a red flame 16) Can you draw a diagram of the atoms that give out red color flame versus a diagram for the atoms that give out green color flame? 17) What role does the flame in the flame test play in this demonstration?

Phase Three: second prompt “Energy level diagrams” In chemistry we use different types of diagrams to represent what is going on in the atomic level, please take a look at this diagram (give them the diagram), and I am going to ask you questions about it. 14) Do you see any features in your drawing(s) that are represented in this diagram (my 205 diagram)? (only ask to High school students unfamiliar with energy level diagrams)

There are some features that your diagram and this diagram have in common. I will ask you some questions about this diagram. 15) What does the n mean? 16) What do the dotted lines mean? 17) What does the Energy axis mean? 18) Why do the numbers next to the energy axis mean? 19) Why does 0 (zero) energy mean? 20) What does this symbol (point at ∞) mean? SAY: Sometimes chemists use these diagrams like the one I showed you with additional arrows on it.(Show them the two diagrams one with arrow up and another one with arrow down)

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21) Can you tell me what these arrows mean?

Phase four (Comparing the experiments in the flame tests with energy level diagrams) 22) Would either or both of these diagrams (pointing at the two previous diagrams) be connected to the flame test you just did? 23) If they say neither ask why? 24) If they point at one of then ask why? 25) What does the other one (the one that they did not choose) represent? Earlier you mentioned that you saw green, orange and red color flames in that effect 26) Can a diagram for atoms giving out green, orange and red color flames be the same? If yes, 27) why are they the same or similar? If not, 28) How would they be different? 29) Is there something that you might like to add or take away in this diagram (show to the one choose) to show how is connected to what you observe in the flame test

Now, look at this diagram to respond to the following questions

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30) Can you have the release of energy if not energy is input? 31) Can you have that arrow (the one that you chose) without the other arrow? 32) What happens to the atom during the atomic release of energy (use their language)? 33) In what manner are the flame test and the diagram related to each other? 34) Do you think the flame test is a good demonstration of atoms releasing energy (use his or her own words)? 35) Why or why not? 36) Do you think the energy diagram is a good demonstration of atoms releasing energy (use his or her own words for emission) 37) Why or why not? 38) When would a chemist use the flame test? 39) When would a chemist use a diagram like this? (Show the student emission energy diagram)?

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Appendix L

Interview Transcript

Arthur Male Comments

AP High school class Periodic table is available for the Suburban public high school student.

One year of regular high school chemistry Length:41(min):39 (sec) v(video)

Ana Do you agree to allow me to record our discussions? Minor Assent

Arthur Yes

Ana Do you understand that you may ask me to turn off the recorder at any time and that I will turn it off without asking any questions?

Arthur Yes

Ana Ok, good. Next I want to tell you that I am interested in YOUR ideas. The questions I have are meant to start a discussion between us so that I can learn about your ideas. If you do not understand a question, you should tell me and ask me to ask the question in another way. Also, if you do not want to answer a question, you can tell me and I will move on to the next question. Do you understand that you can ask me any questions at any time and that you do not have to answer any question that you do not want to answer?

Arthur Yes

Ana Ok, good. Lastly, I will not use your name when I discuss my research. Do you understand that no one will be able to know what YOU specifically told me? Even your teacher won’t know, so he/she can’t hurt or improve your grade. Do you agree to continue to participate in this research?

Arthur Yes

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Ana Ok, thanks, let me remind you two important things, Phase 1 please speak clearly and slowly, and take as much time as you need.

Arthur Ok

Ana Ok, scientists know that atoms can absorb and release 1:26v energy, what I want to talk to you about today is specifically about the release of that energy. What can you tell about how atoms release energy?

Arthur When bonds between different atoms break within a molecule or in an ionic compound, the breaking of the bond releases certain amount of energy.

Ana In what forms of energy atoms release energy?

Arthur Umm, various different forms, as light, heat, radiation

Ana Is there a way that you can represent in a picture, a diagram, an atom releasing energy?

Arthur Yeah, 2:29v

Ana Ok, this is like drawing molecules or what type of picture do you want me to draw?

Ana It is up to you 2:44

Arthur Because I can make a cartoon

Ana Ooh, that’s ok, any picture that comes to mind, that you learn in class, or that you would like to use, that you created, any of those is fine

Arthur Ok well, the one that I can think of that I learned in 2:55v biology and chemistry is when something, like a glucose molecule breaks down, it is almost like a combustion Page 149 Livescribe reaction, where you have C2,H3,O2, the chemical formula plus O2 yields CO2 + H2O (student writing in Livescribe) , ok, so the bonds within the sugar molecule will break into

CO2 and H2O, and that will release energy and like in any other combustion reaction, for example like in a piece of wood which it is an organic compound, it will release, in

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most cases, heat, which you will feel the heat, which it is exothermic and it will also release a light energy which is the flame that you see 4:08

Ana Ok, now we are going to do the flame test, I brought three 4:18 substances, the green is copper chloride, then I have two white substances, lithium chloride and sodium chloride. Phase 2 Here are the wet sticks so you can get some of the powders and put it in the flame, but before you do the flame tests, I’m going to ask you a prediction question, what do you think is going to happen to the copper chloride when you put it in the flame?

Arthur When I put it in the flame is going to emit a certain type 4:52 of light and that will be associate with the element, the compound is made of Copper chloride flame test

Ana Ok, then let’s do the flame test, let’s turn this on, (pause, sounds turning flame on) can you explain what you see?

Arthur I see a green flame, and this is kind of, when the copper chloride burns there are bonds breaking, one way the energy being released is in this case is that certain wavelength of light that it is being emitted.

Ana You said when bonds are breaking, what type of bonds are breaking?

Arthur Well, in this case since it is copper chloride, it’s an ionic compound so it is going to be ionic bonds

Ana Ok, at the atomic level, what is happening to, in this case, 6:36 ions or elements in the copper chloride?

Arthur Well… um. Is there any other way you can explain that?

Ana Well, you kind of already answered that question. You said the ionic bonds are breaking, so, is there something else going on at the atomic level?

Arthur Um… nothing I can think of at the top of my head.

Ana Ok, ok, let’s continue and do the other two substances. LiCl and NaCl

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Before you do the flame test for both, can you predict flame tests what is going to happen to the lithium chloride and sodium chloride?

7:13

Arthur Well, when I was in chemistry 1, we did some flame tests 7:42 for the “unknown lab” and I distinctly remember copper chloride emitting a green/blue/tealish color. I’m sure the lithium chloride and sodium chloride will also emit a certain color, a wavelength, but I’m not exactly sure which color it will be.

7:43

Ana So we will see a change in the color of the flame

Arthur Right!, and also I think one of the ways that you could see that it is a chemical reaction occurring is if there is ummm, when you see a change, an irreversible change then you‘ll know that there is a chemical reaction 7:48 occurring so in this case I guess lithium chloride emits a red color, wavelength of light,

Ana You can continue with the next one, the last one will be sodium chloride and describe what you see please

Arthur Ok, sodium chloride when flamed It emits a yellow- orange color flame, yellow wavelength of light, it’s soo cool, I want to keep doing that, hee hee (removing the stick from flame)

Ana (smile) Ok can you explain why the white color powders give out different color flames in comparison to the green powder giving out green color flame?

Arthur visible light is within a spectrum of about 400 to 700 nm, and that is associate with certain level or amount of energy being release when the bonds break, so lithium chloride breaks there is a different level of energy within that bond, as supposed to sodium chloride or even copper

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chloride, and that why it emits a different color because it is a different amount of energy a different wavelength

Ana So nothing to do with the green substance emitting green flame

Arthur Probably not, as far as I know

Ana What determines the color of the flame that you see in the 10:12 flame test?

Arthur The amount of energy at first, the amount of energy is 10:13 associate with certain wavelength in the light spectrum at that wavelength at the light spectrum and we see a certain color and that is the flame we see as the color of the flame

Ana Can you draw a diagram of atoms that give out red color 10:40 flame versus a diagram for atoms that give out a green color flame?

Arthur You have the lithium, it has one valence electron chloride Page 149 also has one, and that is where the bond occurs so and I Livescribe have to associate with a certain color?

Ana Yes,

Arthur Well, looking at this, there is a certain level of attraction within the bond and therefore when it breaks, lithium chloride emitted a reddish color so the wavelength is 11:42v longer and that wavelength is associate with it being red, that is what you see, because red , the color red that we see, is a longer wavelength as oppose to the sodium chloride, so when that breaks (referring to the sodium

chloride) it releases a shorter wavelength and that is associate with the yellow- orange color that we saw. Now when you have a shorter wavelength that means that there is more energy being release so we can assume within sodium chloride the bond energy , the bond enthalpy is

greater than that of lithium chloride, and that can be

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determine by the wavelength 13:16

Ana Thank you, what is the role of the flame in the flame test? 13:26v

Arthur The role of the flame is almost like a catalyst ,it’s what breaks the bond

Ana Do the substances have energy before you heat them up? 13:42

Arthur Yeah I think it is not kinetic energy I think it is potential 13:46v energy that is within the bond and that is the energy that get release when we put it in the flame which it is then kinetic energy, energy of motion or energy that we see being release

Ana Is there a limit of how much energy atoms can gain the 14:05v flame?

Arthur This is more of a hypothesis, but I think if you were to put 14:16v so much energy into an atom, a certain atom, the identity of that atom of that element will change. I think that’s how sometimes scientists came out with the unknown elements, I think they hit it with so much energy, either in the form of protons or electrons that it changed the overall 14:38 structure of the single atom therefore changing it into a

new element, so I think to stay within the round of being the same atom, the same element, I think there is a limit of 15:20 how much you can put into it

Ana Do you know what controls that limit of much energy you can put within one atom without changing the atom?

Arthur I think it is the sublevels, (student begins to draw) I think 15:43v LiveScribe let’s take chlorine for example, so all of these different 149 electrons are on a different sublevel, there is 1s2,2s2, 2p6, 3s2and then 3p5 and that’s how we denoted chlorine, so when , can you ask that question again I forgot where I was going?

Ana Sure yes, what is it that is controlling that limit of how much energy can an atom gain without changing its

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identity?

Arthur Ok, ok, I think then it has to do more with the protons inside, when you hit an atom with so much energy, there is a certain amount of energy that an element or an atom needs, in order to release or lose an atom or gain an atom or gained an electron, excuse me, so when you hit it with that certain amount of energy, let’s say a proton shoots Page 149 off, therefore identifying that atom and changing it into a Livescribe new one, so I think that’s what controls it when electrons or protons are lost or gain, or hitting it with energy is going to cause it

Ana Would you please draw a diagram representing an atom 17:21 gaining energy? And a different diagram of atoms releasing energy? You can draw together or separate, it is ok,

Arthur So when you take an atom that has different sublevels, so we will make this one 1s and this is 2s and this is 2p, let’s take something, let’s take oxygen for example, so it is 2 going to be 1s , so excuse me, that’s wrong (marking X 18:23v on the wrong drawings) so 1s2, you have an up spin and a down spin, and you can see by when you are going to oxygen you see that in the first sublevel 1s1 or1s you can see that this is 1s1and this is 1s2 and you can see that it has a full sublevel, or subshell right there, similarly in the 2s you can see an up spin and a down spin electron, now when you get to 2p (student grabbed periodic table) you see that it has 1,2,3 and then it only has one more so I think representing it in a diagram where it gains energy or loses energy is where it stays, or when you hit it with energy it wants to stay almost as lazy as possible, the atom wants to be as lazy as possible, so the electron is Livescribe page going to moved and I think, this is the best I can do to 149 show an atom gaining or loosing energy, it is with the movement of electrons, so you know, I don’t exactly where here but arbitrarily you can say that this electron will move into this state or for example in hybrid orbitals, the electron may move into something that has something of a lower sublevel, lower shell, and that denotes a lower

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level of energy and a higher level of steadiness and stability and that’s where it shows energy being lost or gained, it is how the atom reacts to it when you hit it with energy what changes within the atom to make it more 21:05v stable, because quote on quote it wants to be as lazy as possible

Ana In chemistry we used diagrams to represent what is going Phase 3 on at the atomic level, this is an energy level diagram, have you ever seen a diagram similar to this one?

Arthur No, but some things I can recognized like energy joules, that stuff I can recognized but I haven’t seen anything in this format

Ana I will ask you some questions about this diagram, you 21:56v mentioned that you recognized the energy axis. What does the energy axis mean in this diagram?

Arthur It is almost the independent variable so, are there two axis 21:58v (pointing at ground state)?

Ana These are multiple lines (pointing at all lines in the graph)

Arthur I think at a certain level of energy on the line, correspond to I guess something on the whole entire dotted line,

Ana What does the n mean in the diagram and the n has numbers, 1,2,3,4,5,6

Arthur Usually when we are doing chemistry, it symbolizes 23:24v moles

Ana What do the numbers next to the energy axis mean, and let me point that this is -218, -200, -100, all the way to zero?

Arthur It is the amount of energy that a certain number of moles an atom has, mmm (student thinking), I guess I can’t have negative energy, (student turns the diagram 90 degrees counterclockwise), (pointing at the energy axis)it denotes 23:51v joules per atom, so I guess I never thought about that, but I guess it is the amount of energy in joules each atom has so I guess an atom at negative 200, whatever atom that

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might be -200 times 10 to the 20th power of energy

Ana Ok, what does the zero energy mean? 24:39v

Arthur Zero energy? It may correspond to, to, let’s take an PT (periodic table) example (taking periodic table) the noble gases they are very, very, unlikely to bond to anything because they have full sublevels full shells, it fills the octet rule, I think that when you say zero (energy) I think that it means it is almost a calculation of how stable that atom is how likely it is to either gain or lose energy and something that is at

zero it is kind of like helium or neon, or argon, something that is very stable something that it is unlikely to gain or 25:44v lose energy, by creating bonds with others atoms

Ana What does this symbol infinity mean in this diagram?

Arthur (pause) so I’m not sure exactly what it means but at zero, so I’m guessing infinity has some sort of correspondence to a zero amount of energy, so an infinity amount of moles has zero energy, that is my best guess, kind of 26:27v connecting the dots there

Ana Ok, some students had alluded that there are not differences between energy levels and orbitals, do you agree with that statement?

Arthur (pause) No I don’t agree with that, I think orbitals are 26:50v where the electrons occupied space within that electron cloud that is certain orbital and the energy level is the amount of energy that the electron has when is in that certain level so, for example like hybrid orbitals, people never say, hybrid energy level, because I think each electron is associate with a certain amount of energy, that

is gain or lost when an electron is introduce into that energy level or when that energy level or when that 27:18 energy level loses an electron so the orbitals I think are the imaginary cloud, this includes hybrid orbitals where the electron lies around the nucleus but the energy level is 28:08 the amount of energy, that the electron possesses

Ana Sometimes chemists used these diagrams with additional arrows in it (showing diagrams) this is a more complete

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energy level diagram, can you tell me what these arrows Phase 4 mean? 28:27v

Arthur Yeah, my best guess will be in this one where the arrow is pointing up, when you increase the amount of moles, because I think the y axis, it is almost like a y axis the vertical line denotes energy is independent, so when you change the number of moles, the amount of energy changes so as you increase the amount of moles, the amount of energy also increases, in the same way in the

down pointing diagram, as you decrease the amount of moles the amount of energy decreases 29:22v

Ana Would either of both of these diagrams be connected to 29:21 the flame test you did earlier?

Arthur Perhaps, if you were to calculate the number of moles that 29:32 were on the wet stick, of the compound how many moles was on there, I think then you can tell how much overall energy is being release, when you put it to the flame, for example let’s say that there were two moles of compound, that would release a certain amount of energy, that kind of 29:58 does not make sense because if you increase the amount

of moles, is losing less energy but I can’t really think of anything else.

Ana Ok. You explain the reason why the arrow pointing up is 30:42 connected to the flame test, but what about the other one (other diagram)?

Arthur See that is where it doesn’t make sense, when you decrease the amount of moles you would think that decreases the amount of overall energy being lost but in this case it is increasing because the negative numbers is getting more negative, which means there is more energy being release, so you know as far as the arrows go and how that relate to the flame test I’m not exactly sure because my logic obviously some faults in it.

Ana Can you have the decrease in energy or the release in 31:43v energy if not energy is input?

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Arthur Well, not I don’t think so, unless you have some kind of enzyme, because when you draw a graph, there is something you call activation energy so in something that is losing energy, something that is exothermic like the flame test, you have you put in energy before you lose it and this area from here to here (dotted line in student drawing) represents the energy that you are putting in, in order for the reaction to occur, that can be in the form of a catalyst, or in biology it can also be an enzyme, but the 32:32v way an enzyme works it can be that it decreases the amount of activation energy required for the reaction to completed or to occurred. But yeah in most cases you have to add energy for the reaction to occur but I’m sure there are incredibly spontaneous reactions that occur with such a minimum identifiable amounts of energy that you put in so miniscule that you can’t really calculate how much

Ana So can you have one arrow without the other one? 33:50

Arthur (pause) based on what I said about the activation energy, it seems as though you can’t but, can I draw in this?

Ana Sure, just use the regular pen, draw as much as you want

Arthur I guess that kind of corresponds to the drawing that I did 34:21 here, when you a certain amount of energy, you know, you put in certain amount of energy and that is the up Student altered the arrow and when it releases energy that’s when that down diagram provided. arrow comes from, so I think it shouldn’t be an arrow here See scanned (arrow pointing up) it really should stop, and in the same picture below: case it really shouldn’t be an arrow there (arrow pointing down), it kind of represents when you put energy and that’s when it increases and when it releases energy that’s when the decrease comes from

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Ana Ok, I have two questions that might sound redundant but I’m going to ask them, what happens to the atom during the atomic release of energy?

Arthur One single atom within the molecule or within the ionic 35:31 compound it becomes free, in a way it breaks apart from the whole, one of the carbon atoms within glucose (going back to first drawing)it is free of the overall molecule and I think that happens to most of the atoms, you can see that

it creates carbon dioxide and water, that obviously is

completely different than C2H3O2 so it breaks off but it also creates some sort of bonds to became stable once

again

Ana In what manner, is the flame test and the diagram that you corrected here related to each other?

Arthur You are putting energy into the system, into the copper chloride or lithium chloride and that is represented by the flame, when you heated it, it is gaining energy and in the form of that light, that wavelength is releasing energy, and 37:07v that is what correspond to this graph, that when you put the flame on increase the heat, the energy in it, that’s what the up arrow comes from, and almost suddenly it loses

energy in the form of wavelength of light and that’s when the down arrow comes from 37:33

Ana So this increase and decrease of energy is done by atoms or by breaking bonds, at the beginning you told that it is

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done by breaking bonds? 37:52

Arthur Right, right, I think the acquiring of energy is happening in the bonds, completely within the bonds, I think two atoms will make up a certain amount of bonds, but really the energy lies within that bond 38:16

Ana Do you think the flame test is a good demonstration of atoms releasing energy?

Arthur Yeah, I think that for any beginning chemistry class. It is a great visualization of how bonds loose energy because is very easily seen in the form of different colors of light, the 38:24 flame colors

Ana Do you think energy diagrams are good demonstrations of atoms releasing energy?

Arthur Until you have a clear understanding of how this diagram 38:51 works, I don’t think it is a good representation, it seems that the labeling is somewhat incomplete, but once you talk about it this is a more practical and methodical way of understanding that certain amount of energy is gain and release and you can manipulate as you want to show any level of energy being gained or lost as oppose to the flame test where you can’t exactly manipulate it to show a certain amount of energy being gained or lost, and also this is paper, so it is frozen there and with the flame it is actually real world so you can’t exactly freeze it and show what the graph can show but you know you have to have a certain level of understanding of how the graph works to show a good change in energy

Ana When would a chemist use the flame test? 40:04v

Arthur Like a chemist, a professional chemist?

Ana Yes,

Arthur To identify what atoms, what elements are within a certain compound, having prior knowledge of what colors certain elements emit you can use the flame test to identify the unknown compound, that’s what I used it for,

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I’m not a professional chemist but that is the way we used it

Ana Ok, When would a chemist use a diagram like this?

Arthur Almost in a sort of number crunching fashion where they need to do calculations, they need to be able to visualize what is occurring in a concrete fashion where you can see that it is going to happen every single time with experience, you know with a lot of experiments, there is a certain amount of error, of flaw and with these graphs, unless you make mistakes on the graphs, there really isn’t

a lot of mistakes you can make, so it is all very concrete, easy to use once you understand it, you can make 41:36v relationships, you can manipulate, you can calculate using the graphs much more

Ana Thank you! That was the last question. 41:39v

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Appendix M Coding sample

Student Text Code

Arthur.APHS a glucose molecule breaks down, it is almost like a combustion reaction, where you have Bond breaking C2H3O2, the chemical formula plus O2 yields CO2 + H2O , ok, so the bonds within the sugar molecule will break into CO2 and H2O, and that will release energy Arthur.APHS When the copper chloride burns there are bonds breaking, one way the energy being released Bond breaking is in that certain wavelength of light that it is being emitted Arthur.APHS Arthur Bond breaking One single atom within the molecule or within the ionic compound it becomes free, in a way it breaks apart from the whole, one of the carbon atoms within glucose (going back to first drawing)it is free of the overall molecule and I think that happens to most of the atoms, you can see that it creates carbon dioxide and water, that obviously is completely different than C2H3O2 so it breaks off but it also creates some sort of bonds to became stable once again

Arthur.APHS When the copper chloride burns there are bonds breaking, one way the energy being released Bond breaking and is in that certain wavelength of light that it is being emitted color of light Arthur.APHS 400 to 700 nm, and that is associate with certain level or amount of energy being release when Bond breaking and the bonds break, so lithium chloride breaks there is a different level of energy within that bond, Energy as suppose to sodium chloride or even copper chloride, and that why it emits a different color because it is a different amount of energy a different wavelength Arthur.APHS when you have a shorter wavelength that means that there is more energy being release so we Bond enthalpy_ can assume within sodium chloride the bond energy , the bond enthalpy is greater than that of associated wiht lithium chloride, and that can be determine by the wavelength bond energy Arthur.APHS there is a certain level of attraction within the bond and therefore when it breaks, lithium Bond streght chloride emitted a reddish color so the wavelength is longer and that wavelength is associate associated with with it being red, that is what you see, because red , the color red that we see, is a longer bond attraction and wavelength as oppose to the sodium chloride, so when that breaks color emitted Arthur.APHS I think the acquiring of energy is happening in the bonds, completely within the bonds, I think Bonding_energy lies two atoms will make up a certain amount of bonds, but really the energy lies within that bond within bonds

Arthur.APHS Arthur Bonding_formation One single atom within the molecule or within the ionic compound it becomes free, in a way it of bonds increases breaks apart from the whole, one of the carbon atoms within glucose (going back to first stability drawing)it is free of the overall molecule and I think that happens to most of the atoms, you can see that it creates carbon dioxide and water, that obviously is completely different than C2H3O2 so it breaks off but it also creates some sort of bonds to became stable once again

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Appendix N

Sample MNF analysis of Samuel, a GC student during Phase I

Interviewer: Scientists know that atoms can absorb and release energy. Today, I want to talk to you about that release of energy, how atoms release energy. What can you tell me about how atoms release energy?

Samuel: (Mode A) Atoms release energy in two ways; it is either endothermic or exothermic. Endothermic is when the energy would be absorbed and exothermic is when the energy is going to be released

Interviewer (probing for a representation): Can you draw a representation of an atom releasing energy?

Samuel: I think, (Mode B) you would have a staircase type picture (Figure 1) and then one big drop here, this would represent the first level of energy and then you will go up, the energy would be increasing when you are trying to go to the second level of energy because of a… (Mode C) I forgot what it’s called, but it is because of the idea of becoming a noble gas, where you are wanting a full octet or a full energy orbital and later on, goes to the third energy level, fourth energy level and so on, where the energy needed would be decreasing as you are going up the levels of energy

Interviewer: Can you represent what you just said? How does the energy decrease as you go up the levels?

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Figure 1. Samuel’s Drawing Node: Energy level diagram as staircase. Samuel (explaining his drawing in Figure 2): I would say (Mode D) as you go up the levels. It will be uhh, well it sorts of looks like this graph where you have like a logistics like type. I would say…. it is the wrong direction (eliminates first graph with a scribble), where here (top of Y-axis, marked 1) is like the first energy state and then come down to a certain point. This is what I think about atomic emission

Figure 2. Samuel’s Drawing Node: First energy state.

Samuel Nodes within Mode Modes Phase I • Atoms release energy in two ways Mode A • Energy is absorbed in an endothermic reaction • Energy is released in an exothermic reaction

• Drawing Node: Energy levels as staircase (Figure 1) Mode B • Large energy gap between 1st & 2nd energy levels, in comparison to other levels

• Atoms move towards stability • Atoms move towards noble gas configuration Mode C • Atoms want full octets • Atoms want full orbitals

• Drawing Node: First energy level represented by log function graph (Figure 2) Mode D • Gap between energy levels decreased going up levels. • Used term ‘Atomic emission’

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Appendix O

Sample MNF analysis of Lucy, a UD student during Phase II

Interviewer (after the copper (II) chloride flame test): What do you think is happening to the atoms of the copper chloride?

Lucy: Once they’re (atoms) stuck onto the stick (wooden coffee stirrer) they’re being put into the flame. (Mode A) Some of the salt is dissolving onto the stick, but, um once that water evaporates, the salt is actually getting separated into its individual atoms and those atoms are getting into their excited states, (Mode B) and um it is more of the metal rather than the chloride that is showing the color, because those electrons in the d orbitals can hop up to more excited states, which is not really present in the chloride

Interviewer: Okay, we’re going to do the same flame test for the other substances, sodium chloride and lithium chloride…. Before we put them into the flame what do you think is going to happen to those compounds?

Lucy: Um, (Mode C) the same thing, probably not the same color change (be)cause the atoms are different sizes, but different color of the flame because of the metal ion

Interviewer: Okay, go ahead. What do you observe?

Lucy: (Mode D) The flame is orange, which, since it’s blue originally that means that it’s probably turning orange (be)cause of the actual metal, like the other one turned green

Interviewer:…Following up with the colors you saw earlier, you saw a green flame the first time with copper chloride, and then you saw an orange flame with sodium chloride; um can you draw a diagram of the atoms, say for the orange flame and the green flame?

Lucy: (Mode E) Ok, let’s see…. sodium is definitely smaller than copper, um, these are not actually what the shells look like, and so the electrons here (pointing at sodium atom, on the left drawing Figure 1), if they go on to an excited state they have less room to relax back down, 226 whereas in copper they can go to a higher state and they have more energy to give off when they relax back, so yeah because the copper electrons have more room, I guess to relax back down to the ground state, so greater energy

Figure 1. Lucy’s Drawing Node. Sodium (left) and copper (right) Bohr atomic models.

Lucy Nodes within Mode Modes Phase II • Compound dissolved in water • Water evaporates in flame Mode A • Salt separates into individual atoms in the flame • Individual excited atoms move into excited states • Individual metal atoms are responsible for the change in color of the flame Mode B • Metal (copper) atoms have d orbitals, but chloride does not

• Metal atoms were responsible for the change in color of the flame of sodium chloride Mode C • Different ionic/atomic radii cause different color flames

• Bunsen burner flame is blue Mode D • Sodium chloride produces an orange flame • Metal atoms/ions are responsible for the change in color of the flame • Sodium atom is smaller than copper atom • Drawing Node: Bohr models of copper and sodium atoms Mode E • Electrons move up to excited states • Different ionic/atomic radii cause different color flames • Energy gap corresponds to atomic/ionic radii • Excited electrons relax back to ground state

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Appendix P Sample Writing of an Item

Topic: Release of energy in flame test Version: 2 Intention: Testing what idea of atomic release of energy student possesses Stem: In the flame test of Copper chloride, ions release energy by ______

Responses:

A. Losing (outer) electrons B. Gaining electrons C. Breaking bonds D. Splitting subatomic particles E. Electronic transition(s)

Correct answer: E. Electronic transition(s)

Quotes:

A. Losing electrons (Release of Energy)

Alex (Non-AP chemistry): In the flame test the valence electrons on the substances were lost to make them more stable that’s why the color of the flame stopped and when back to normal (color) after a while, so this chart (the arrow down diagram) shows that after a while after the flame test loses electrons become more stable the energy decreases

Darren (Non-AP chemistry): for an atom that is losing energy, I draw (Figure 1) the electrons that were in the atoms itself leaving the atom, so it became positive and it lost the energy that they already gained from the electrons…. Atoms can be given off electrons

Figure 1. Darren’ drawing

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Steven (Non-AP chemistry): (Atoms lose energy) when they lose electrons

Rachel (UD): When atoms loose energy, [pause], when is releasing energy, one of them is gaining an electron and one of them is losing an electron, to go up in energy level, you have to gain an electron, but this is going to coincide with gaining an electron and this one is going to be losing an electron

Rachel (UD) (referring to diagram with arrow up and down): One of them is gaining an electron and one of them is losing an electron (referring to the arrows), just trying to figure out, to go up in energy level (arrow up), you have to gain an electron, so this is going to coincide with gaining an electron and this one is going to be losing an electron (arrow down)

Samantha (UD): I think that it is (atom release of energy) when they give of electrons to another element or something…like when sodium and chloride combined

B. Gaining electrons (release of Energy)

Meredith (Non-AP chemistry): the atoms will gain an electron here from another atom and it would lose the energy

Meredith (Non-AP chemistry) when an atom loses an electron it gains energy and vice versa

Meredith (Non-AP chemistry) (referring to diagram with an arrow up) It means how much energy is being increased so it will..also means how many electrons are being lost for that reaction

Meredith (Non-AP chemistry): When two substances are combining in this case potassium and fluoride (student draws Figure 2), I’ll use potassium and fluoride again, and there are positive and negative, one is releasing energy to and this one is gaining energy and energy on the side, like this diagram (pointing at diagram provided to student) is increased, so because they are not losing any substance they are just combining, they are exchanging electrons.

Figure 2. Meredith’s drawing

Rachel (UD): (Referring to diagram with arrow up and down) One of them is gaining an electron 229

and one of them is losing an electron (referring to the arrows), just trying to figure out, to go up in energy level (arrow up), you have to gain an electron, so this is going to coincide with gaining an electron and this one is going to be losing an electron (arrow down)

C. Breaking bonds

Tatiana (AP chemistry): they (atoms) released energy from breaking bonds and how atoms always want to be, or everything in the universe always wants to go to its lowest state of energy, so it will decompose and that will release energy sometimes or like when heat is giving off through a chemical reaction

Arthur (AP chemistry): a glucose molecule breaks down, it is almost like a combustion reaction, where you have C2H3O2, the chemical formula plus O2 yields CO2 + H2O, ok, so the bonds within the sugar molecule will break into CO2 and H2O, and that will release energy

Arthur (AP chemistry): When the copper chloride burns there are bonds breaking, one way the energy being released is in that certain wavelength of light that it is being emitted

Diego (AP chemistry): Energy can be stored in many ways in molecules and atoms, in the bonds between molecules, energy is stored in potential energy, when those bonds are broken, it can be release as light energy or heat energy when electrons in some elements jumped up energy levels because they gain energy and they fall back down, they released energy and that’s how we see the light, and the scientists can harness that potential energy between the bonds by doing fission to release huge amount of energy, that’s the basis behind nuclear power

Jason (AP chemistry): The substances have energy in their bonds, but they only access to that energy is to break the bonds or go through some sort of chemical reaction and by breaking those bonds energy can be release, but right now I don’t think you can just like , for example sodium chloride you can’t put that in your hand and gain energy, you have to eat some of that maybe, it is edible and by eating that I can provide passed some energy

Tatiana (AP chemistry): So it is a bright yellow flame, it is frazzle maybe because the bonds are easily broken

Tatiana (AP chemistry): I know that it is like an spontaneous reaction then bonds are broken, and heat is giving off because bonds are broken and those happen like over time, spontaneously, so you don’t put energy into it, I think for example maybe rust

Waldo (AP chemistry): energy is stored in the bonds between atoms, not in the actual atoms itself, and when you break the bonds that’s when energy is released

Waldo (AP chemistry): The energy release by the bonds breaking through the heat, and depending in what wavelength is the visible light spectrum, wherever that lands, that’s the color you see Tina (GC): I know that atoms can be broken, and then they can come together so they are two kinds of change that will caused the energy to be released 230

D. Splitting subatomic particles

Diego (AP chemistry): (student drawing, Figure 3) if you have an atom with a bunch of protons and neutrons and adding another neutron usually to it, then it can became unstable and too heavy and then break down into two other elements, releasing other neutron and that adds a large amount of energy outwards, and then this can go into other ones which then release energy and so on and so forth

Figure 3. Diego’s drawing

Diego (AP chemistry): depends what kind of release of energy, if there is the release of energy light wise, nothing happens to the nucleus, the electrons changes which releases energy, but if it releases energy in the idea of fusion, atoms pushed together becoming one, and in fission, one atom becoming so unstable that splits apart releasing energy, because of those bonds over there

Jason (AP chemistry): uranium atom, which is radioactive and it is going to its half-life, I’m not sure what it breaks down to, I said calcium but it also releases gamma radiation which it is another form of energy

Jason (AP chemistry): The second picture (Figure 4) is just a uranium atom, which is radioactive and it is going to its half-life, I’m not sure what it breaks down to, I said calcium but it also releases gamma radiation which it is another form of energy

Figure 4. Jason’s drawing

Susan (AP chemistry): I know what from passed tests that’s how they got nuclear warfare by splitting the atom, I think that’s how they release energy, when they are splitting the atom because I think it takes tremendous amount of energy to keep it together

Susan (drawing): The only way I can think of, so this is an atom and its nucleus is over here, it’s got the electrons floating but I think what they do is that they split the nucleus apart and that’s

231 how it releases energy…this (Figure 5) would be an example of an atom being split up there with the protons and neutrons, just being spread in two

Figure 5. Susan’s drawing

Michael (GC): Like in an atomic bomb, I forget what element it is but the rod is like jammed into the middle of the atom and then the atom splits and that is what causes an explosion which it releases energy

Darren (Non-AP chemistry): Atoms release energy by splitting the nucleus apart and all the little particles in the nucleus going outward, and releasing all the energy that way (drawing) that’s a nucleus (pointing at drawing, Figure 6) and it is releasing all the protons and neutrons in different directions

Figure 6. Darren’s drawing

Darren (Non-AP chemistry): the green flame has less protons and neutron going, like leaving the atom itself, and for the red flame I drew more neutrons and protons flying out of the nucleus, because red has a higher wavelength so I would think that more particles are leaving to give that wavelength

Figure 7. Darren’s drawing

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Appendix Q

Inventory Expert Validation Informed Consent Form

Before agreeing to provide feedback, please be sure to thoroughly read this consent form. If you have any questions or concerns, please contact Ana Vasquez Murata , Department of Chemistry and Biochemistry, 354 Hughes Hall, Miami University, Oxford, Ohio 45056 or email at [email protected] or my research advisor, Dr. Stacey Lowery Bretz, at [email protected]. If you have any questions about your rights as human subjects please contact the Office for the Advancement of Research and Scholarship (513-529-3600) or [email protected]

I agree to participate in this research study regarding what students know about atomic emission. I agree to provide feedback on the validity of the items in the flame test concept inventory. The information I provide may be used for additional research or publications; however, since my name is not used, my identity is protected. I have had the opportunity to ask any questions I might have about my participation in this study and they have been answered to my satisfaction. By typing my name below, I certify that I have read the consent form and agree to participate in this study.

______Research Participant Date

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Appendix R

Expert Flame Test Concept Inventory

Choose the one best answer. Important data about the flame test can be found on the back of periodic table.

1) What happens to copper (II) chloride when it is held in the flame of a Bunsen burner?

A. Copper (II) chloride turns into gaseous copper ions and chloride ions. B. Copper (II) chloride dissociates into solid copper and chlorine gas. C. Copper (II) chloride oxidizes with air to form copper oxide. D. Copper (II) chloride undergoes a combustion reaction. E. Copper (II) chloride undergoes a redox reaction.

2) What is the role of the flame in a flame test?

A. It provides an activation energy. B. It acts as a catalyst. C. It acts as an indicator. D. It provides the heat of reaction. E. It acts as a source of energy.

3) In the flame test of copper (II) chloride, atoms gain energy, by ______.

A. losing valence electrons B. gaining valence electrons C. exciting valence electrons D. forming bonds

4) The amount of energy that ions can absorb in a flame test is limited by______.

A. the temperature of the Bunsen burner flame B. how many orbitals are available in the ions C. the unique electronic transitions of cations D. the breaking of bonds in the compound

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5) A flame test for CuCl2 produces a green flame, while a flame test for LiCl produces a red flame because Cu and Li ______.

A. have different ionic radii B. have different orbital energies C. have a different number of inner shells D. are a transition metal and an alkali metal, respectively

6) In the flame test of CuCl2, what must happen to the compound before it can release energy?

A. Bonds must break. B. Subatomic particles must split. C. Atoms must move and collide with each other. D. Electrons must absorb energy.

7) When lithium chloride is placed in the flame of a Bunsen burner, the ions ______.

A. rearrange to form a new compound B. change phases from solid to gas C. expand by gaining electrons D. shrink by losing electrons

8) The particular color of the flame in a flame test is due to the______.

A. color of the compound B. location of elements in the periodic table C. number of valence electrons D. electrons dropping into inner energy levels E. energy gap between an excited state and the ground state

9) In the flame test of copper (II) chloride, what happens to the compound when held in the flame of a Bunsen burner?

A. CuCl2(s)  Cu(s) + Cl2(g)

2+ B. CuCl2(s) Cu (g) + 2Cl-(g)

C. 2CuCl2(s) + 3O2(g) 2CuO(s) + 4ClO(g)

D. 2CuCl2(s) + O2(g) 2CuO (g) + 2Cl2(g)

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10) In the flame test of copper (II) chloride, atoms release energy by______.

A. losing valence electrons B. gaining valence electrons C. splitting subatomic particles into smaller components D. valence electrons returning to their ground state

11) A student drew this model of an atom to represent the flame test. Which arrows best represent what happens in the flame test?

A. A then B B. A then C C. D then B D. D then C

12) If we replace the gas of the Bunsen burner with another gas that is 4 times hotter, will lithium chloride change into a different compound? What color will the flame(s) be?

Will lithium chloride change into What color will the flame(s) be? a different compound?

A No red B No multiple colors, including red C No single color other than red D Yes single color other than red

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13) Which diagram best represents the appearance of color in the flame test?

A B

C D

A) A

B) B

C) C

D) D

14) The reason for my answer to question 13 is because the diagram shows ______.

A. that the compound does not absorb energy from the flame B. excited electrons returning back to their ground state C. the energy increase necessary for the color change D. the ions in the compound gaining and losing electrons

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15) If we run the flame test using a mixture of 0.1 g of vanadium (IV) chloride (blue color flame) and 0.2 g of lithium chloride (red color flame), what color flame(s) will we see?

A. Red flames B. Blue flames C. Purple flames D. Red flames and blue flames

16) The reason for my answer to question 15 is ______.

A. there is more lithium chloride in the mixture. B. there is more energy released by vanadium (IV) chloride than by lithium chloride. C. each substance will show its unique color separately. D. there is an exchange of electrons between the compounds to create a mixture of colors.

17) If we run the flame test using a mixture of 0.5 g of vanadium (IV) chloride (blue color flame) and 0.5 g of lithium chloride (red color flame), what color flame(s) will we see?

A. Red flames B. Blue flames C. Purple flames D. Red flames and blue flames

18) The reason for my answer to question 17 is ______.

A. there is the same amount of each compound in the mixture. B. there is more energy released by vanadium (IV) chloride than by lithium chloride. C. each substance will show its unique color separately. D. there is an exchange of electrons between the compounds to create a mixture of colors.

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Appendix S

Alpha Flame Test Concept Inventory (Alpha FTCI)

Choose the one best answer. Important data about the flame test will be handed to you along with a periodic table.

1) What happens to copper (II) chloride when it is held in the flame of a Bunsen burner?

A. Copper (II) chloride dissociates into gaseous copper ions and chloride ions. B. Copper (II) chloride dissociates into solid copper and chlorine gas. C. Copper (II) chloride oxidizes with air to form copper oxide. D. Copper (II) chloride undergoes a combustion reaction. E. Copper (II) chloride undergoes a redox reaction.

2) What is the role of the flame in a flame test?

A. It provides the activation energy. B. It acts as a catalyst. C. It acts as an indicator. D. It provides the heat of reaction. E. It acts as a source of energy.

3) In the flame test of copper (II) chloride, what happens to the valence electrons as the ions gain energy?

A. Valence electrons are lost. B. Valence electrons are gained. C. Valence electrons move to higher energy orbitals. D. Valence electrons form new bonds.

4) The amount of energy that a cation can absorb in a flame test is limited by______.

A. the temperature of the Bunsen burner flame B. the unique electronic transitions of the cation C. how many orbitals are available in the cation D. the breaking of bonds in the compound

5) A flame test for NaCl produces an orange flame, while a flame test for LiCl produces a red flame because Na+ and Li+ ______.

A. have different ionic radii B. have same ionic charges C. have different energy gaps between ground state and excited state D. are both alkali metals producing colors of similar wavelengths

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6) In the flame test of CuCl2, what must happen to the compound before it can release energy?

A. Bonds must break. B. Subatomic particles must split. C. Atoms must move and collide with each other. D. Electrons must absorb energy.

7) When lithium chloride is placed in the flame of a Bunsen burner, the ions______.

A. rearrange to form a new compound B. change phases from solid to gas C. expand by gaining electrons D. shrink by losing electrons

8) The particular color of the flame in a flame test is due to the______.

9) In the flame test of copper (II) chloride, what happens to the compound when held in the flame of a Bunsen burner?

A. CuCl2(s)  Cu(s) + Cl2(g) 2+ B. CuCl2(s) Cu (g) + 2Cl-(g)

C. 2CuCl2(s) + 3O2(g) 2CuO(s) + 4ClO(g)

D. 2CuCl2(s) + O2(g) 2CuO (g) + 2Cl2(g)

10) In the flame test of copper (II) chloride, ions release energy by______.

A. losing valence electrons B. gaining valence electrons C. splitting subatomic particles into smaller components D. valence electrons returning to their ground state

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11) A student drew this model to represent the flame test. Which arrows best represent what happens to the ions in the flame test?

A. A then B B. A then C C. D then B D. D then C

12) Another student looked at the drawing in question 11 and pointed out two possible problems with the model:

i. The model works only for single electron atoms. ii. The energy levels drawn are equidistant from one another.

Which of these possible problems are limitations when interpreting the flame test?

A. i B. ii C. Both are limitations D. Neither is a limitation

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13) Which diagram best represents the appearance of color in the flame test?

A B

C D

A. A B. B C. C D. D

14) The reason for my answer to question 13 is because the diagram shows ______.

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15) If we replace the gas of the Bunsen burner with another gas that is 4 times hotter, will lithium chloride change into a different compound? What color will the flame(s) be? Will lithium chloride change What color will the flame(s) be? into a different compound? A No red B No multiple colors, including red C No single color other than red D Yes single color other than red

16) A flame test for CuCl2 produces a green flame, while a flame test for LiCl produces a red flame because Cu2+ and Li+ ______.

A. have different ionic radii B. have different ionic charges C. have different energy gaps between ground state and excited state D. are a transition metal and an alkali metal, respectively

17) If we run the flame test using a mixture of vanadium (IV) chloride and lithium chloride containing 1 mole of V4+ (blue color flame) and 1 mole of Li+ (red color flame), what color flame(s) will we see? A. Red flames B. Blue flames C. Purple flames D. Red flames and blue flames

18) The reason for my answer to question 17 is ______.

A. each substance will show its unique color. B. there is the same amount of each ion in the mixture. C. there is more energy released by vanadium (IV) chloride than by lithium chloride. D. there is an exchange of electrons between the compounds to create a mixture of colors.

19) If we run the flame test using a mixture of vanadium (IV) chloride and lithium chloride, it was calculated that the mixture contains 1 mole of V4+ (blue color flame) and 2 moles of Li+ (red color flame), what color flame(s) will we see?

A. Red flames B. Blue flames C. Purple flames D. Red flames and blue flames 20) The reason for my answer to question 19 is ______.

A. each substance will show its unique color. B. there is more lithium ion in the mixture. C. there is more energy released by vanadium (IV) chloride than by lithium chloride. D. there is an exchange of electrons between the compounds to create a mixture of color.

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Appendix T

Think Out-loud Protocol

Validation Score 4 in written test Q#d ->Q#d interview Score 6 in interview chosen answer in GC# 3 Blue is student spontaneous answer written test  R=researcher Green is elimination of other distractors or the question in chosen answer in S=student general interview Red is choosing an answer from the given answers R Let’s talk about the handout given to you, was it confusing to you in any manner? S I know what’s going on because I done these before, and I think the handout looked fine R Let’s start with the first question, please read it out loud Question 1 S What happens to copper (II) chloride when it is held in the flame of a Bunsen burner?

R Before we uncover the answers do you have an answer for the question? S I just know that it changes color R Ok, go ahead uncover the answers, go ahead and chose an answer, S (pause) reading quietly, I think copper 2 chloride undergoes a combustion reaction, R Ok, D S Should I mark it? R Yeah, Why did you choose that answer? S I don’t know, because I think copper 2 chloride, after it is burned ends in like water and copper something, R The first time you answer this question, you chose E, any ideas Q1E->Q1D why? S I was going between the two just now, again, I chose combustion because I’m pretty sure that the products are water and something else, R Ok, so your final answer is D or E S I’ll go with D (Copper (II) chloride undergoes a combustion reaction) R Ok, let’s continue with number 2 Question 2 S What is the role of the flame in the flame test? (pause) I think 3:00 when the substance is in the flame and it changes color I think is to say whether it oxidizes or something, just to start the reaction R Ok, so let’s uncover the answers

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S (pause) I don’t think it acts as, I feel that all the answers could be possible, I think is A R Why are you choosing A S Because the heat, because to do the reaction, the substance need to like start I guess R The first time you answer this question, you chose D, any ideas Q2D->Q2A why? S I think I was thinking the same thing, I don’t think d is right though, R So you stick with A S Yeah R Ok, let’s do number 3 please read it out loud Question 3 S In the flame test of copper (II) chloride, what happens to the Unable to answer valence electrons as the ions gain energy? I have no idea

R It’s ok, let’s uncover the answers S (reading) I don’t think anything is lost,(ring form phone) R Do you want me to pause and wait? S Oh no no, it is just a text, I need to learn all this for next week, I Q3C*->Q3C* don’t think anything is gained (B), I don’t think is A, but I ‘m going with either C or D. I think that they move to higher energy orbitals (C) R Ok, let’s do number 4 Question 4 S (reading)The amount of energy that a cation can absorb in a flame test is limited by (pause, student looked like s/he doesn’t know R Any ideas S No R Let’s look at the answer then S Student reading answers, I think is D (the breaking of bonds in Q4D->Q4D the compound) R Lets’ do 5 Question 5 S A flame test for NaCl produces an orange flame, while a flame test for LiCl produces a red flame because Na+ and Li+----are different, I will not had filled out the blank R Go ahead, uncover the answers S Are orange and red closer in wavelengths, I don’t know, I would go with C (have different energy gaps between ground state and excited state) R The first time you answered this question you chose D any Q5D->Q5C*->Q5D reasons? S Now that I think about I don’t know how to determine the wavelength, I probably do , but I don’t remember, R If you have to pick an answer, which one will you pick? S I I know how to do the color thing I would, I probably would, I

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may go with D R Let’s do 6 Question 6 S In the flame test of CuCl2, what must happen to the compound before it can release energy? I should know this, shouldn’t bonds be , energy should be transfer, something R Ok, let’s uncover the answers, S Bonds must break subatomic particles , atoms must move and Q6A->Q6A collide with each other, electros must absorb energy, I think it is A (Bonds must break) R Lets’ do 7 Question 7 S When lithium chloride is placed in the flame of a Bunsen burner, the ions … the ions break , I don’t know R Ok, let’s uncover S I don’t think is B (change phases form solid to gases), I ‘ll go with Q7A->Q7A A (rearrange to form a new compound)

R Let’s do number 8 Question 8 S The particular color of the flame in a flame test is due to the ..chemical compounds R Ok, lets uncover S I think is B ( location of elements in the periodic table) Q8B->Q8B R Let’s do the next one Question 9 S In the flame test of copper 2 chloride what happens to the compound when held in the flame of a Bunsen burner…(pause, rereading) it goes to a combustion reaction R This question gives you symbolic answers, please uncover the answers S ( looking at answers) I think it is D R The first time you answer C S I don’t know, I don’t think C is right because I don’t think the

oxygen mix up with both of them (2CuCl2(s) + 3O2(g) 2CuO(s) + 4ClO(g) R Ok, so you stick with your answer D Q9C->Q9D S Yes, R Ok, let’s do the next one 10 Question 10 S In the flame test of copper (II) chloride, ions release energy by.. transferring energy, R Let’s see the answers S (pause reading) I think it would be A (losing valence electrons)

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R The first time you answer this question you answer B (gaining valence electrons) S Because I don’t think they can release energy by gaining valence electrons, I think if it loses (electrons) is releasing energy like A R You will stay with A S A Q10B->Q19A R Ok, let’s do number 11, just looked at the diagram for this question S A student drew this model to represent the flame test. Which arrows best represent what happens to the ions in the flame test? .. (pause) I think is B ( A then C) R The first time you chose C (D then B) S Because if I looked in this one it says it is losing valence electrons 16:47 (looking at her answer on question 10), I think is B, just because they started by going towards that + thing then out R Ok, let’s do number 12 Question 12 S Another student looked at the drawing in question 11 and pointed out two possible problems with the model: The model works only for single electron atoms. The energy levels drawn are equidistant from one another. Which of these possible problems are limitations when interpreting the flame test?....Uhmm I think it is both (C) because the model doesn’t work for multi electrons atoms, the second one is not because the orbitals or energy levels are not like in the drawing, like circles R So you answer is C S Yes, R The first time you answer this question you answer D S I don’t know , I don’t know why R So you will stick with your answer C S Yes, C is yes Q12D->Q12C* Consistent

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correct R Let’s do number 13 Question 13 S Which diagram best represents the appearance of color in the Q13D->Q13D flame test…I totally learn about this, but did not understand consistent anything, I think it is D? R Ok, let’s do number 14 Question 14 S The reason for my answer in question 13 is (reading reasons) Q14C->Q14C pause, I think is c but that is not answering (question13) D, or question 13 I guess, R In Q13 you chose D S Yes, R And the reason why you chose D, was because of this (the energy increase necessary for the color change), or do you have a reason that might not be here? S No, because , I don’t know, I just remember seeing this in class (refereeing to diagram) R So is it familiar to you? S Yes, R And the reason, why are you picking c in number 14? S I think the flame test is to see the color change , so the flame is 21:23 like the energy change for the compound to change color and wherever color it is, R Ok, let’s do number 15 Question 15 S If we replace the gas of the Bunsen burner with another gas that is 4 times hotter, will lithium chloride change into a different compound? What color will the flame(s) be? (reading) would lithium chloride change into a different compound NO, NO, NO what color flames? I don’t think it will change into , oh I think it will change into a different compound , R And what about the color? S It will be a single color , other than red (D)

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R So it is D S Yes R The dirst time you answered B that it will not change into a Q15B->Q15D different compound and that the flames will be multiple colors including red S I think it is D, because I think that if the flame is hotter, then the 23:00 lithium chloride will have the chance to fully loose one of the other parts of it either lithium or chloride and be replaced R What about the color, you said it will change into a different compound, S The color will be just one color R Let’s go to number 16, and please cover the answers Question 16 S A flame test for CuCl2 produces a green flame, while a flame test for LiCl produces a red flame because Cu2+ and Li+…(reading ) answers, I think is B R Why are you choosing B? S Ok, (looking at periodic table) I’m looking to see if copper and lithium are really what it says they are, R Sure S Lithium is and alkali metal and copper is a transition metal that Q16 D->Q16B- could be too (D), yeah I think it is D >Q16B R Ok, final answer? S Yeah R Ok, let’s do number 17 Question 17 S If we run the flame test using a mixture of vanadium (IV) chloride and lithium chloride containing 1 mole of V4+ (blue color flame) and 1 mole of Li+ (red color flame), what color flame(s) will we see, I think it is D, just because I accidentally done that before and it has come out those two colors, I contaminated the sample, R Did you do the flame test in this class? S No I did it in high school

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R Before you answered B S I don’t know why R Ok, your answer is just D S Yeah R Let’s do 18 Question 18 S The reason for my answer to question 17 is.. I think is A, each substance will show its own color R The first time you answer this question you chose B S That is because I though blue will be seen but I think it is A R Next question number 19 Question 19 S If we run the flame test using a mixture of vanadium (IV) chloride 27:23 and lithium chloride, it was calculated that the mixture contains 1 + mole of V4+ (blue color flame) and 2 moles of Li (red color

flame), what color flame(s) will we see, oh well I think it is the same D R Ok, let’s see the answers, next please Question 20 S The reason for my answer to question 19 is..(reading) I think it is A, I think the amount of substance doesn’t matter R The first time you answer these two questions, you answer the same in Q19 but you chose a different reason, reason A, any ideas why S Probably because I though since there is more moles of lithium then it should, I don’t think I was paying attention R Then your final answer in 20 is? Q20B->Q20A S A R The last question is if you have any problems understanding Overall the questions? Anything confusing? comments S The questions were fine, I just don’t understand the concepts

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R Ok, did you feel that it was too long for you? S I just remember that they didn’t give us enough time, R Did you feel rush? S Yeah, they told us that we have 10 minutes to do it and it took us like 20 R Ok, thank you very much I appreciate you coming over to give me your input

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Appendix U

Instructor’s signed permission for administering inventory

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Appendix V

Invitation to participate in Chemistry Concept Inventory Project (Sample)

Through a grant from the National Science Foundation, my graduate students and I have developed several concept inventories for use in undergraduate chemistry. These multiple-choice assessments focus on students’ understanding of key concepts in chemistry. A brief description of each concept inventory can be found below.

I am writing to invite you to use these concept inventories in your classroom during the fall 2012 semester. You may use one, two, three, or all four of them. These concept inventories are designed to be given after you have taught and tested this material with your students. Each concept inventory requires 10-15 minutes for students to complete. Some faculty administer this during lecture and some administer it at the start of a laboratory experiment, so it can be given in either lecture or lab. We will mail you paper copies of each inventory, scantron “bubble sheets” for students to use to record their answers, a short “script” to read as directions before administering the concept inventory, and a postage paid federal express envelope to return all the concept inventories and the scantrons back to us. There is no cost to you for participating in this project.

In return, we will provide you with data analysis regarding your students’ performance on each question so that you might use this formative feedback in your classroom. Student responses will be anonymous but they will be asked to grant permission for their responses to be used in our research study. This research has been reviewed and approved by the Miami University Institutional Review Board under exemption certificate #E00532.

Here is a brief description of each concept inventory, as well as a short description of how they were developed:

• Acid-Base Concept Inventory – explores student understanding of acid base reactions written as balanced equations • Bonding Representations Inventory – explores student understanding of covalent and ionic bonding using representations such as Lewis structures, 3-D models, etc. • Flame Test Concept Inventory – explores student understanding of electron structure and atomic emission using color pictures of flame tests • Molecular Attractions Concept Inventory – explores student understanding of intermolecular forces using color pictures of paper chromatography experiments

The concept inventories were developed through interviews with students, asking them to explain demonstrations (e.g., paper chromatography or flame tests), or to interpret models showing the structure of molecules, or to interpret commonly used symbols such as balanced equations or energy level diagrams. Students’ descriptions of these events were used to write multiple choice items that include not only the correct answer, but also the most frequently expressed alternative conceptions of the students.

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If you are interested in administering one or more of these concept inventories, please reply to this email at your earliest convenience with the following information about you and your students:

1. Which concept inventories do you wish to administer? 2. How many students will take each inventory? 3. By what date do you need to receive each inventory? (If you wish to give the Molecular Attractions Inventory but this comes at the very end of the fall semester, it would be possible to give this at the start of the spring semester, e.g., at laboratory check-in) 4. What is the name of each course in which you will use the concept inventories (e.g., General Chemistry I, Honors Chemistry I, etc.)? 5. What is the name of the textbook for each course in which you will use the concept inventories? 6. How many years have you been teaching chemistry? 7. Do you consider your university to be an R1, comprehensive, liberal arts, or community college? 8. Is your college public or private? 9. What is your mailing address so we can send a fed ex package containing your concept inventories?

Thank you very much for considering this opportunity. Please do not hesitate to call me or email me with any questions you may have.

Dr. Stacey Lowery Bretz

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Appendix W

Final version of FTCI

Your teacher will receive a summary of how all the students in your class answer these questions. Your individual responses will remain anonymous. Your teacher will not know how you answered each question, nor how many questions you answered correctly. We would like to use your answers as part of a research project here at Miami University. Again, all your answers will remain anonymous. o If you are willing to give us permission to use your answers as part of our research, please fill in FORM 1 in the lower right hand corner of the scantron form. o If you do not want us to use your answers as part of our research, please fill in FORM 2 in the lower right hand corner of the scantron.

Thank you very much.

Flame Test Concept Inventory

Choose the one best answer. Important data about the flame test will be handed to you along with a periodic table.

1) What is the role of the flame in a flame test?

A. It overcomes the activation energy barrier for the reaction. B. It acts as a catalyst to speed up the reaction. C. It acts as an indicator. D. It acts as a source of energy.

2) In the flame test of copper (II) chloride, what happens to the valence electrons as the compound gains energy?

A. Valence electrons are lost. B. Valence electrons are gained. C. Valence electrons move to higher energy orbitals. D. Valence electrons form new bonds.

3) The amount of energy that a compound can absorb in a flame test is limited by______.

A. the temperature of the Bunsen burner flame B. the unique electronic transitions of the metal C. how many orbitals are available in the metal D. the formation of new bonds in the compound

4) A flame test for sodium chloride produces an orange flame, while a flame test for lithium chloride produces a red flame because sodium and Lithium______.

A. have different ionic radii B. both form ions with +1 charges, producing similar colors C. have different energy gaps between ground state and excited state D. are both alkali metals

5) In the flame test of CuCl2, what must happen to the compound before it can release energy?

A. Bonds must break. B. Electrons must absorb energy. C. Subatomic particles must split. D. Atoms must move and collide with each other.

6) When lithium chloride is placed in the flame of a Bunsen burner, the compound______.

A. rearranges to form a new compound B. changes phase from solid to gas C. expands by gaining electrons D. shrinks by losing electrons

7) The particular color of the flame in a flame test is due to the______.

A. energy gap between an excited state and the ground state B. location of elements in the periodic table C. number of valence electrons D. electrons dropping into inner energy levels

8) Copper (II) chloride releases energy in a flame test by______.

A. losing valence electrons B. gaining valence electrons C. breaking bonds in the compound D. valence electrons returning to their ground state

9) A student drew this model to represent the flame test. Which arrows best represent what happens to the electrons in the flame test?

A. B then A B. C then D C. D then B D. C then A

10) Another student looked at the drawing in question 9 and pointed out two possible problems with the model:

i. The model works only for atoms with one electron. ii. The energy levels drawn are equidistant from one another.

Which of these possible problems are limitations when interpreting the flame test?

A. i B. ii C. Both are limitations D. Neither is a limitation

Continue

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11)

The red color appears during the flame test of Lithium chloride due to ______and it is best represented by arrow ______in the diagram above.

A. Atomic absorbance, X B. Atomic absorbance, Y C. Atomic emission, X D. Atomic emission, Y

12) The reason for my answer to question 11 is because the diagram shows ______.

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13) If we replace the gas of the Bunsen burner with another gas that is slightly hotter, will lithium chloride change into a different compound? What color will the flame(s) be?

Will lithium chloride change What color will the flame(s) be? into a different compound?

A No Red

B No multiple colors, including red

C No single color other than red

D Yes single color other than red

14) The reason for my answer in question 13 is______.

A. any increase in temperature will cause ionization and change the identity of the substance B. the compound can absorb and release only certain amounts of energy C. a higher energy state will be filled, producing a different colored transition D. the compound will absorb more energy so more wavelengths will be emitted

15) A flame test for copper chloride produces a green flame, while a flame test for lithium chloride produces a red flame because copper and lithium ______.

A. have different ionic radii B. both form ions with different ionic charges C. have different energy gaps between ground state and excited state D. are a transition metal and an alkali metal, respectively

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16) If we run the flame test using a mixture of 1 mole of vanadium (IV) chloride (blue color flame) and 1 mole of lithium chloride (red color flame), what color flame(s) will we see?

A. Red flames B. Blue flames C. Purple flames D. Red flames and blue flames

17) The reason for my answer to question 16 is ______.

A. each substance will show its unique color. B. there is one mole of each compound in the mixture. C. there is more energy released by vanadium (IV) chloride than by lithium chloride. D. there is an exchange of electrons between the compounds to create a mixture of colors.

18) If we run the flame test using a mixture of 1 mole of vanadium (IV) chloride (blue color flame) and 2 moles of lithium chloride (red color flame), what color flame(s) will we see?

A. Red flames B. Blue flames C. Purple flames D. Red flames and blue flames

19) The reason for my answer to question 18 is ______.

A. each substance will show its unique color. B. there is more moles of lithium than vanadium in the mixture. C. there is more energy released by vanadium (IV) chloride than by lithium chloride. D. there is an exchange of electrons between the compounds to create a mixture of colors.

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V.1 Color Handout of FTCI

Flame Test : Wooden sticks were soaked in water. They were then used to place compounds into the flame of a Bunsen burner. Please refer to these pictures as needed.

Green

Green Green

Before During After

Figure 1. Flame test of CuCl2, copper (II) chloride.

Red White White

Before During After

Figure 2. Flame test of LiCl, lithium chloride.

Orange White White

Before During After

Figure 3. Flame test of NaCl, sodium chloride

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Appendix X

Instructor’s directions for administering concept inventory

**to be administered in class only**not to be done as homework**

Please read this ‘script’ to students verbatim BEFORE passing out the concept inventory:

1. I am handing out a questionnaire about a chemistry topic we have already learned about this semester. This questionnaire will help me understand what you have learned about this topic. 2. This questionnaire is part of a research project at Miami University in Ohio. The researchers will score your responses and let me know what the class, as a whole, thinks, but I will not know your individual answers. Your answers on this test will be completely anonymous. 3. To keep your answers anonymous, do not write your name on the scantron form. Note that the name ‘ANONYMOUS’ has already been written in. 4. Please note the box at the top of the first page. Miami University would like to use this data in a research study to better understand how college students think about chemistry. All your answers are anonymous. If you are willing to give permission for your answers to be used in the research study, please fill in the bubble for FORM 1 in the lower right hand corner of the scan-tron. If you do NOT want your answers to be part of the research study, then please fill in the bubble for FORM 2 in the lower right hand corner of the scan-tron. 5. Please do not write on the questionnaire. Only write on the scantron. 6. Choose what you think is the one best answer for each question. 7. Please answer all questions and do not leave any blank. There is no penalty for guessing. 8. You will have 15-20 minutes to complete the questionnaire. 9. You may begin.

When students have completed the inventory, or 20 minutes has passed (whichever comes first), please collect all the scantrons, all the concept inventories, and any data sheets that accompanied the concept inventory. Place EVERYTHING into the box and attach the Fedex label and return to:

Dr. Stacey Lowery Bretz Miami University 651 E. High Street Department of Chemistry & Biochemistry Oxford, OH 45056

If there are any questions or difficulties, please call Stacey Lowery Bretz at 513-529-3731.

Thank you very much!

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