Chapter 7 Periodic Properties of the Elements Learning Outcomes
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Additional Teacher Background Chapter 4 Lesson 3, P. 295
Additional Teacher Background Chapter 4 Lesson 3, p. 295 What determines the shape of the standard periodic table? One common question about the periodic table is why it has its distinctive shape. There are actu- ally many different ways to represent the periodic table including circular, spiral, and 3-D. But in most cases, it is shown as a basically horizontal chart with the elements making up a certain num- ber of rows and columns. In this view, the table is not a symmetrical rectangular chart but seems to have steps or pieces missing. The key to understanding the shape of the periodic table is to recognize that the characteristics of the atoms themselves and their relationships to one another determine the shape and patterns of the table. ©2011 American Chemical Society Middle School Chemistry Unit 303 A helpful starting point for explaining the shape of the periodic table is to look closely at the structure of the atoms themselves. You can see some important characteristics of atoms by look- ing at the chart of energy level diagrams. Remember that an energy level is a region around an atom’s nucleus that can hold a certain number of electrons. The chart shows the number of energy levels for each element as concentric shaded rings. It also shows the number of protons (atomic number) for each element under the element’s name. The electrons, which equal the number of protons, are shown as dots within the energy levels. The relationship between atomic number, energy levels, and the way electrons fill these levels determines the shape of the standard periodic table. -
An Alternate Graphical Representation of Periodic Table of Chemical Elements Mohd Abubakr1, Microsoft India (R&D) Pvt
An Alternate Graphical Representation of Periodic table of Chemical Elements Mohd Abubakr1, Microsoft India (R&D) Pvt. Ltd, Hyderabad, India. [email protected] Abstract Periodic table of chemical elements symbolizes an elegant graphical representation of symmetry at atomic level and provides an overview on arrangement of electrons. It started merely as tabular representation of chemical elements, later got strengthened with quantum mechanical description of atomic structure and recent studies have revealed that periodic table can be formulated using SO(4,2) SU(2) group. IUPAC, the governing body in Chemistry, doesn‟t approve any periodic table as a standard periodic table. The only specific recommendation provided by IUPAC is that the periodic table should follow the 1 to 18 group numbering. In this technical paper, we describe a new graphical representation of periodic table, referred as „Circular form of Periodic table‟. The advantages of circular form of periodic table over other representations are discussed along with a brief discussion on history of periodic tables. 1. Introduction The profoundness of inherent symmetry in nature can be seen at different depths of atomic scales. Periodic table symbolizes one such elegant symmetry existing within the atomic structure of chemical elements. This so called „symmetry‟ within the atomic structures has been widely studied from different prospects and over the last hundreds years more than 700 different graphical representations of Periodic tables have emerged [1]. Each graphical representation of chemical elements attempted to portray certain symmetries in form of columns, rows, spirals, dimensions etc. Out of all the graphical representations, the rectangular form of periodic table (also referred as Long form of periodic table or Modern periodic table) has gained wide acceptance. -
The Development of the Periodic Table and Its Consequences Citation: J
Firenze University Press www.fupress.com/substantia The Development of the Periodic Table and its Consequences Citation: J. Emsley (2019) The Devel- opment of the Periodic Table and its Consequences. Substantia 3(2) Suppl. 5: 15-27. doi: 10.13128/Substantia-297 John Emsley Copyright: © 2019 J. Emsley. This is Alameda Lodge, 23a Alameda Road, Ampthill, MK45 2LA, UK an open access, peer-reviewed article E-mail: [email protected] published by Firenze University Press (http://www.fupress.com/substantia) and distributed under the terms of the Abstract. Chemistry is fortunate among the sciences in having an icon that is instant- Creative Commons Attribution License, ly recognisable around the world: the periodic table. The United Nations has deemed which permits unrestricted use, distri- 2019 to be the International Year of the Periodic Table, in commemoration of the 150th bution, and reproduction in any medi- anniversary of the first paper in which it appeared. That had been written by a Russian um, provided the original author and chemist, Dmitri Mendeleev, and was published in May 1869. Since then, there have source are credited. been many versions of the table, but one format has come to be the most widely used Data Availability Statement: All rel- and is to be seen everywhere. The route to this preferred form of the table makes an evant data are within the paper and its interesting story. Supporting Information files. Keywords. Periodic table, Mendeleev, Newlands, Deming, Seaborg. Competing Interests: The Author(s) declare(s) no conflict of interest. INTRODUCTION There are hundreds of periodic tables but the one that is widely repro- duced has the approval of the International Union of Pure and Applied Chemistry (IUPAC) and is shown in Fig.1. -
Dmitri Mendeleev
DOWNLOADABLE EXTRAS Atomic Structure: Part 1 1 Dmitri Mendeleev Dmitri Mendeleev was born on the 8th of February 1834 in Siberia, Russia. His father who was a teacher of the arts and politics, died when he was only thirteen. He was one of a large family and is thought to possibly have had 17 brothers and sisters. Due to his father’s death and a failed family business (a glass factory that burnt down) the family were very poor. Despite this, his mother wanted him to be educated at a higher level so she moved the family to St Petersburg in order for Dmitri to attend school. After graduating he became a teacher in the area of science. His passion was chemistry and he studied the capillarity of liquids (ability of a liquid to fl ow in a narrow space without any suction or pumping, like when water moves against gravity up a straw placed in a glass of water), the components of petrol and the spectroscope (a device that uses light to identify unknown materials). Because chemistry at the time was so disorganised, Mendeleev saw a need to establish a set of rules and guidelines that would be universal (able to be used across the world). He started by writing two very successful text books that included all of his chemistry knowledge. However he felt that this wasn’t enough and that the concepts of chemistry were too broad and unlinked. In 1869 he started to write a system that ordered the elements as these were the main concept behind a lot of other chemistry. -
ELECTRON AFFINITY - the Electron Affinity Is the ENERGY CHANGE on Adding a Single Electron to an Atom
189 ELECTRON AFFINITY - the electron affinity is the ENERGY CHANGE on adding a single electron to an atom. - Atoms with a positive electron affinity cannot form anions. - The more negative the electron affinity, the more stable the anion formed! - General trend: As you move to the right on the periodic table, the electron affinity becomes more negative. EXCEPTIONS - Group IIA does not form anions (positive electron affinity)! valence electrons for Group IIA! period number - To add an electron, the atom must put it into a higher-energy (p) subshell. - Group VA: can form anions, but has a more POSITIVE electron affinity than IVA valence electrons for Group VA! Half-full "p" subshell! To add an electron, must start pairing! - Group VIIIA (noble gases) does not form anions full "s" and "p" subshells! 190 "MAIN" or "REPRESENTATIVE" GROUPS OF THE PERIODIC TABLE IA VIIIA 1 H He IIA IIIA IVA VA VIA VIIA 2 Li Be Read about these in B C N O F Ne Section 8.7 of the Ebbing 3 Na Mg Al Si P S Cl Ar textbook! 4 K Ca Ga Ge As Se Br Kr 5 Rb Sr In Sn Sb Te I Xe 6 Cs Ba Tl Pb Bi Po At Rn 7 Fr Ra Chalcogens Alkaline earth metals Halogens Alkali metals Noble/Inert gases 191 The representative (main) groups GROUP IA - the alkali metals valence electrons: - React with water to form HYDROXIDES alkali metals form BASES when put into water! - Alkali metal OXIDES also form bases when put into water. (This is related to METALLIC character. -
Ionization Energies Bonding: Electron Affinity Bonding
Announcements – 9/13/00 Bonding: Ionization Energies n Labs begin TODAY! n Ionization Energy (IE) n Old exams on website -quantifies the tendency of an electron to leave an atom in the gas phase: n Problem Set Solutions? n Exam #1 X (g) X+ (g) + e- DE = IE -covers matl thru this Friday (Ch 1&2) IE: -always positive (energy ADDED) -email/contact me ASAP if you have a conflict with exam time -INCR across row -DECR down a group n Demo and Quiz on Friday 1 2 Bonding: Electron Affinity Bonding: Electronegativity n Electron Affinity (EA) n Electronegativity (EN) - -quantifies ability of an atom to attract an e in -combines IE and EA terms to give the the gas phase relative ability of an atom to attract e-’s to X (g) + e- ® X- (g) -DE = EA itself when bonded to another atom EA: -it’s the energy released upon addition of an electron to an atom EN: -INCR across a row -can be positive or negative -DECR down a group - (pos: atom wants the e -Best to consider DEN for a bond neg: atom happy as an atom) 3 4 1 EN: Examples Bond Polarity: Dipole Momement n NaCl: Na EN = 0.93 n HCl d+ d- ¬ partial charges DEN = 2.23 (ionic) H – Cl Cl EN = 3.16 2.2 3.2 Polar Covalent bond: share e-, but not equally n O2: O EN = 3.44 DEN = 0 (covalent) -Quantify via: DIPOLE MOMENT (µ) n HCl: H EN = 2.2 µ = d x d Bond length (m) DEN = 0.96 (?) 1 Debye (D) Amt of displaced charge (C) Cl EN = 3.16 (polar covalent) = 3.34 x 10-30 C-m 5 6 Dipole Moment Examples Visualizing Molecules n H2O O EN = 3.44 H EN = 2.2 DEN = 1.24 CH4 -each H-O bond is polar, but does the MOLECULE have -
The Modern Periodic Table Part II: Periodic Trends
K The Modern Periodic Table Part II: Periodic Trends November 13, 2014 ATOMIC RADIUS Period Trend *Across a period, Atomic Size DECREASES as Atomic Number INCREASES DECREASING SIZE Li Na K Rb Cs 2.2.0 1. 0 0 Group Trend *Within a group Atomic Size INCREASES as Atomic number INCREASES Trend In Classes of the Elements Across a Period Per Metals Metalloids Nonmetals 3 4 5 6 7 8 9 10 2 Li Be B C N O F Ne 11 12 13 14 15 16 17 18 3 Na Mg Al Si P S Cl Ar Trend in Ionic Radius Definition of Ion: An ion is a charged particle. Ions form from atoms when they gain or lose electrons. Trend in Ionic Radius v An ion that is formed when an atom gains electrons is negatively charged (anion) v Nonmetal ions form this way v Examples: Cl- , F- v An ion that is formed when an atom loses electrons is positively charged (cation) v Metal ions form this way v Examples: Al+3 , Li+ v METALS: The ATOM is larger than the ion v NON METALS: The ION is larger than atom Trends in Ionic Radii v In general, as you move left to right across a period the size of the positive ion decreases v As you move down a group the size of both positive and negative ions increase Ionization Energy Trends Definition: the energy required to remove an electron from a gaseous atom v The energy required to remove the first electron from an atom is its first ionization energy v The energy required to remove the second electron is its second ionization energy v Second and third ionization energies are always larger than the first Period Trend *Across a period, IONIZATION ENERGY increases from left to right Group Trend *Within a group, the IONIZATION ENERGY Decreases down a column Octet Rule Definition: Eight electrons in the outermost energy level (valence electrons) is a particularly stable arrangement. -
Chapter 8 2013
described by Core Chapter 8 Electrons Wave Function e- filling spdf electronic configuration comprising (Orbital) Valence determined by Electrons described by Aufbau basis for Rules Periodic Quantum which involve Table Numbers which summarizes Orbital Pauli Hund’s which are Energy Exclusion Rule Periodic Properties Electron Configuration and Chemical Periodicity Quantum 4-quantum numbers specify the energy and location of Numbers electrons around a nucleus (all we can know). This numbers are the framework for the “electronic structure Orbital size of an atom”. Principal define & energy n = 1,2,3,.. s defines Name Symbol Permitted Values Property principal n positive integers (1,2,3...) orbital energy (size) Angular Orbital angular l orbital shape (0, 1, 2, and 3 momentum, l defines momentum integers from 0 to n-1 correspond to s, p, d, and f shape orbitals, respectively.) Magnetic Orbital magnetic integers from -l to 0 to +l orbital orientation in space defines ml ml orientation direction of e- spin spin m +1/2 or -1/2 Electron s Spin, ms defines spin Quantum Allowed Schrodinger’s equation gives an exact solution for H- Possible Orbitals Number Values atom, but does not for many electron-atoms. Electron- n Positive integers 1 2 3 electron repulsion in multi-electron split energy levels. 1,2,3,4.... Hydrogen Atom Multi-electron atoms 0 0 1 0 1 2 l 0 up to max Orbitals are of n-1 “degenerate” or Energy the same energy in Hydrogen! ml -l,...0...+l 0 0 -1 0 1 0 -1 0 1 -2-1 0 12 Orbital Name 1s 2s 2p 3s 3p 3d Electrons will Shapes or Boundry fill lowest Surface Plots energy orbitals first! Inner core electrons “shield” or “screen” outer 4-quantum numbers specify all the information we can know the energy electrons from the positive charge of the nucleus. -
Actinide Ground-State Properties-Theoretical Predictions
Actinide Ground-State Properties Theoretical predictions John M. Wills and Olle Eriksson electron-electron correlations—the electronic energy of the ground state of or nearly fifty years, the actinides interactions among the 5f electrons and solids, molecules, and atoms as a func- defied the efforts of solid-state between them and other electrons—are tional of electron density. The DFT Ftheorists to understand their expected to affect the bonding. prescription has had such a profound properties. These metals are among Low-symmetry crystal structures, impact on basic research in both the most complex of the long-lived relativistic effects, and electron- chemistry and solid-state physics that elements, and in the solid state, they electron correlations are very difficult Walter Kohn, its main inventor, was display some of the most unusual to treat in traditional electronic- one of the recipients of the 1998 behaviors of any series in the periodic structure calculations of metals and, Nobel Prize in Chemistry. table. Very low melting temperatures, until the last decade, were outside the In general, it is not possible to apply large anisotropic thermal-expansion realm of computational ability. And DFT without some approximation. coefficients, very low symmetry crystal yet, it is essential to treat these effects But many man-years of intense research structures, many solid-to-solid phase properly in order to understand the have yielded reliable approximate transitions—the list is daunting. Where physics of the actinides. Electron- expressions for the total energy in does one begin to put together an electron correlations are important in which all terms, except for a single- understanding of these elements? determining the degree to which 5f particle kinetic-energy term, can be In the last 10 years, together with electrons are localized at lattice sites. -
Modeling the Shape of Ions in Pyrite-Type Crystals
Crystals 2014, 4, 390-403; doi:10.3390/cryst4030390 OPEN ACCESS crystals ISSN 2073-4352 www.mdpi.com/journal/crystals Article Modeling the Shape of Ions in Pyrite-Type Crystals Mario Birkholz IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany; E-Mail: [email protected]; Tel.: +49-335-56250 Received: 13 April 2014; in revised form: 22 August 2014 / Accepted: 26 August 2014 / Published: 3 September 2014 Abstract: The geometrical shape of ions in crystals and the concept of ionic radii are re-considered. The re-investigation is motivated by the fact that a spherical modelling is justified for p valence shell ions on cubic lattice sites only. For the majority of point groups, however, the ionic radius must be assumed to be an anisotropic quantity. An appropriate modelling of p valence ions then has to be performed by ellipsoids. The approach is tested for pyrite-structured dichalcogenides MX2, with chalcogen ions X = O, S, Se and Te. The latter are found to exhibit the shape of ellipsoids being compressed along the <111> symmetry axes, with two radii r|| and describing their spatial extension. Based on this ansatz, accurate interatomic M–X distances can be derived and a consistent geometrical model emerges for pyrite-structured compounds. Remarkably, the volumes of chalcogen ions are found to vary only little in different MX2 compounds, suggesting the ionic volume rather than the ionic radius to behave as a crystal-chemical constant. Keywords: ionic radius; ionic shape; bonding distance; ionic volume; pyrite-type compounds; di-chalcogenides; di-oxides; di-sulfides; di-selenides; di-tellurides 1. -
1.1 Effective Nuclear Charge 1.2 Effective Nuclear Charge 1.3
Periodic Trends Periodic Trends 1.1 Effective Nuclear Charge 1.2 Effective Nuclear Charge The interaction between the nuclear charge and the Zeff = nuclear charge actually experienced by an valence electrons (how many? how far away?) is electron critical Simplest approximation The nuclear charge experienced by the valence Zeff = Z - # core electrons electrons (Zeff ) impacts how tightly the valence electrons are held Assumption How tightly the valence electrons are held influences atomic size, ionization energy, electron affinity, and Examples reactivity Periodic Trends Periodic Trends 1.3 Effective Nuclear Charge 1.4 Slater’s Rules Slater’s rules acknowledge the imperfect shielding Slater’s rules assume imperfect shielding caused by orbital penetration Zeff = Z – where is calculated using Slater’s rules 1. GthbitlidGroup the orbitals in order: (1s) (2s,2p) (3s,3p) (3d) (4s,4p) (4d) (4f) (5s,5p)… 2. To determine , sum up the following contributions for the electron of interest: a. 0 (zero) for all electrons in groups outside (to the right of) the one being considered b. 0.35 for each of the other electrons in the same ggp(proup (except for 1s group where 0.30 is used) c. If the electron is in a (ns,np) group, 0.85 for each electron in the next innermost (to the left) group d. If the electron is in a (nd) or (nf) group, 1.00 for each electron in the next innermost (to the left) group e. 1.00 for each electron in the still lower (farther in) groups 1 Periodic Trends Periodic Trends 1.5 Using Slater’s Rules 1.6 Using Slater’s Rules What do the 1.0, 0.85 and 0.35 factors mean? Fluorine’s Zeff calculated using the simple approximation = 7 and using Slater’s rules = 5.20. -
Chapter 7 Electron Configuration and the Periodic Table
Chapter 7 Electron Configuration and the Periodic Table Copyright McGraw-Hill 2009 1 7.1 Development of the Periodic Table • 1864 - John Newlands - Law of Octaves- every 8th element had similar properties when arranged by atomic masses (not true past Ca) • 1869 - Dmitri Mendeleev & Lothar Meyer - independently proposed idea of periodicity (recurrence of properties) Copyright McGraw-Hill 2009 2 • Mendeleev – Grouped elements (66) according to properties – Predicted properties for elements not yet discovered – Though a good model, Mendeleev could not explain inconsistencies, for instance, all elements were not in order according to atomic mass Copyright McGraw-Hill 2009 3 • 1913 - Henry Moseley explained the discrepancy – Discovered correlation between number of protons (atomic number) and frequency of X rays generated – Today, elements are arranged in order of increasing atomic number Copyright McGraw-Hill 2009 4 Periodic Table by Dates of Discovery Copyright McGraw-Hill 2009 5 Essential Elements in the Human Body Copyright McGraw-Hill 2009 6 The Modern Periodic Table Copyright McGraw-Hill 2009 7 7.2 The Modern Periodic Table • Classification of Elements – Main group elements - “representative elements” Group 1A- 7A – Noble gases - Group 8A all have ns2np6 configuration(exception-He) – Transition elements - 1B, 3B - 8B “d- block” – Lanthanides/actinides - “f-block” Copyright McGraw-Hill 2009 8 Periodic Table Colored Coded By Main Classifications Copyright McGraw-Hill 2009 9 Copyright McGraw-Hill 2009 10 • Predicting properties – Valence