DOCSLIB.ORG

Standard EPS Shell Presentation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Standard EPS Shell Presentation Tuesday 9/6/16 Chapter 14 - the Atom (finally…) Learning Goals and the Achievement Scale 4, 3, 2, 1, 0 Scoring Scale. Discuss Learning Goals. Pass out Periodic Tables. Nothing warms the soul… Score 2: The student demonstrates no major errors or omissions regarding the simpler details and processes that support the learning goal(s). The student : Can state the key theories or experiments associated with Dalton, Rutherford, Thomson and Bohr. Can compare the relative sizes and charges of the subatomic particles (protons, neutrons and electrons). Can define the 3 fundamental forces (strong nuclear, weak nuclear and electromagnetic) at play in the atom. Can define the terms atom, element, ion and isotope. Can define the terms atomic number, atomic mass, mass number. Can identify the number of protons, neutrons for an atom when given the atomic number and mass. Can state that electrons exist within energy levels that surround the nucleus at a relatively large distance from the nucleus in comparison to the size of the nucleus. Can state how many electrons each energy level can hold. Can draw the electron configuration of ground state atoms. Can draw a generic atomic model of a ground state atom and correctly place, label and indicate the charge of the protons, neutrons and electrons. Score 1: With help (being given word banks, manipulated equations, retakes), the student demonstrates a partial understanding of the simpler details and processes that support the learning goal(s) stated for a Score of 2. Score 0: Even with help, no success Score 4 Example Assessment Items: Academic Vocabulary: Explain how each of the 3 fundamental forces works to Atom Electric Charge hold an atom together. Be sure to list the relative strength Element Neutral and distances over which these forces act. List 3 similarities and 3 differences between an ion and Ions an isotope of Chlorine. Isotopes Atomic Number Draw an atomic model of 13C-2. Score 3 Example Assessment Items: Atomic Mass or Mass Number Explain the key results that were found by 2 of the Protons scientists that we discussed in class. Neutrons What is the role of each of the 3 fundamental forces? How many electrons are found in the first, second, third Electrons and fourth energy levels of the Sulfur +2 ion? ground state excited state energy levels Score 2 Example Assessment Items absorption What is the charge and relative mass of a proton, neutron and electron? emission A _________ is an atom that has gained or lost electrons. elementary force Draw a model of an atom correctly locating the protons, neutrons and electrons. Make sure to label each. strong nuclear force weak nuclear force electromagnetic force Achievement Scale Content Area: Physical Science Grade Level: 9 Unit: Atomic Structure Learning Goals: I can discuss the historical developments leading to the atomic theory and analyze results of key scientists to determine their historical conclusions. I can draw an atomic model and correctly label the subatomic particles and their charges. I can distinguish between elements ions and isotopes. I can discuss the role of the electron in the atoms in terms of energy levels and location in the atom. Score 4: Student demonstrates in-depth inferences and applications of the learning goal(s) and can reconstruct and apply their knowledge from limited information: The student: Can state the timeline associated with the key theories or experiments associated with Dalton, Rutherford, Thomson, and Bohr and how these led to the development of the atomic theory. Can explain that the electrons are not massless but that in comparison to nucleus are insignificant to mass of the atom. Can compare and contrast the role of the 3 fundamental forces in holding together the atom and the relative strength of each forces (strong nuclear, weak nuclear and electromagnetic). Can compare and contrast the terms atom, element, ion and isotope. Can determine the number of subatomic particles in an atom when given the atomic number, atomic mass, mass number, atomic mass unit and/or charge in symbol form. Can identify the number of protons, neutrons and electrons for an atom, ion or isotope when given the least amount of information possible. Can compare and contrast the mass, charge of each subatomic particle. Can identify the energy levels in which electrons exist when given an element, atom or ion in symbol form. Can explain in detail what happens when electrons transfer between energy levels and the differences associated with changes between different energy levels. Can draw an atomic model of atoms, ions and isotopes with minimal information (13C-2). Score 3: Student demonstrates no major errors or omissions regarding the learning goal(s) that were explicitly taught: The student: Can state the key results of the experiments associated with Dalton, Rutherford, Thomson, and Bohr and what this lead each to conclude. Can explain that the electrons are not massless but that in comparison to nucleus are insignificant to mass of the atom. Can explain the role of the 3 fundamental forces (strong nuclear, weak nuclear and electromagnetic) in the atom. Can determine the number of each of the subatomic particles in an atom when specifically given the atomic number, atomic mass, mass number, atomic mass unit and/or charge. Can state the energy levels in which electrons exist when given an atom or ion and its charge. Can explain that energy must be absorbed to change an atom from the ground sate to the excited state and that this transfer (absorption or emission) happens when electrons transfer between energy levels. Can draw atomic models of atoms, ions and isotopes when given specific information (atomic number and mass, charge). The Questions What particles makes up the atom? What is the charge on each particle? What is the mass of each particle? Structure of the Atom In order to understand atoms, we need to understand the idea of electric charge. Electric Charge – A fundamental property of matter that can be either positive or negative. We know of two different kinds of electric charge. Positive and negative. Structure of the Atom Elementary Charge: The smallest unit of electric charge that is possible. The elementary charge can be either positive 1 (+1) or negative 1 (-1) and is indicated by the small letter, e. The only options are whole numbers. +1, +2, +3 (+e, +2e, +3e)… or -1, -2, -3 (-e, -2e, - 3e)… Structure of the Atom “Opposites Attract” Opposite charges attract each other and like charges repel each other. Positive attracts negative charge. Negative repels negative. Positive repels positive. Electric charge in matter Electrically neutral: We say an object is electrically neutral when its total electric charge is zero. The Atom The atom is made up of 3 particles. 2 of these particles make up the nucleus of the atom: Proton: A particle found in the nucleus with a positive charge (+e) exactly equal and opposite to the electron. Neutron: A particle found in the nucleus with a mass similar to the proton but with zero electric charge (neutral). The third particle is found in a cloud (Electron Cloud) that surrounds the nucleus but is far, far away from the nucleus. Electron: A particle with a negative electric charge (–e) found outside of the nucleus in the electron cloud. The Nucleus The protons and neutrons are much larger and more massive than electrons. The mass of the nucleus determines the mass of an atom because the protons and neutrons are much larger and more massive than electrons. A proton has 1,836 times more mass than an electron. The Electron Cloud Area surrounding the nucleus. Contains the electrons. Does NOT contain the nucleus. Put it together: Model of the Atom Nucleus: Contains Protons and Neutrons. Electron Cloud: Contains the electrons far, far (away) from the nucleus. The model… On board. The Answers What particles makes up the atom? Proton, Neutron, Electron. What is the charge on each particle? Proton: +e Neutron: No charge. Electron: -e What is the relative mass of each particle? Electron: 1 Proton: 1836 Neutron: 1839.
Load more

Recommended publications
  • 1.3.4 Atoms and Molecules Name Symbol Definition SI Unit
    1.3.4 Atoms and molecules Name Symbol Definition SI unit Notes nucleon number, A 1 mass number proton number, Z 1 atomic number neutron number N N = A - Z 1 electron rest mass me kg (1) mass of atom, ma, m kg atomic mass 12 atomic mass constant mu mu = ma( C)/12 kg (1), (2) mass excess ∆ ∆ = ma - Amu kg elementary charge, e C proton charage Planck constant h J s Planck constant/2π h h = h/2π J s 2 2 Bohr radius a0 a0 = 4πε0 h /mee m -1 Rydberg constant R∞ R∞ = Eh/2hc m 2 fine structure constant α α = e /4πε0 h c 1 ionization energy Ei J electron affinity Eea J (1) Analogous symbols are used for other particles with subscripts: p for proton, n for neutron, a for atom, N for nucleus, etc. (2) mu is equal to the unified atomic mass unit, with symbol u, i.e. mu = 1 u. In biochemistry the name dalton, with symbol Da, is used for the unified atomic mass unit, although the name and symbols have not been accepted by CGPM. Chapter 1 - 1 Name Symbol Definition SI unit Notes electronegativity χ χ = ½(Ei +Eea) J (3) dissociation energy Ed, D J from the ground state D0 J (4) from the potential De J (4) minimum principal quantum n E = -hcR/n2 1 number (H atom) angular momentum see under Spectroscopy, section 3.5. quantum numbers -1 magnetic dipole m, µ Ep = -m⋅⋅⋅B J T (5) moment of a molecule magnetizability ξ m = ξB J T-2 of a molecule -1 Bohr magneton µB µB = eh/2me J T (3) The concept of electronegativity was intoduced by L.
    [Show full text]
  • Guide for the Use of the International System of Units (SI)
    Guide for the Use of the International System of Units (SI) m kg s cd SI mol K A NIST Special Publication 811 2008 Edition Ambler Thompson and Barry N. Taylor NIST Special Publication 811 2008 Edition Guide for the Use of the International System of Units (SI) Ambler Thompson Technology Services and Barry N. Taylor Physics Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899 (Supersedes NIST Special Publication 811, 1995 Edition, April 1995) March 2008 U.S. Department of Commerce Carlos M. Gutierrez, Secretary National Institute of Standards and Technology James M. Turner, Acting Director National Institute of Standards and Technology Special Publication 811, 2008 Edition (Supersedes NIST Special Publication 811, April 1995 Edition) Natl. Inst. Stand. Technol. Spec. Publ. 811, 2008 Ed., 85 pages (March 2008; 2nd printing November 2008) CODEN: NSPUE3 Note on 2nd printing: This 2nd printing dated November 2008 of NIST SP811 corrects a number of minor typographical errors present in the 1st printing dated March 2008. Guide for the Use of the International System of Units (SI) Preface The International System of Units, universally abbreviated SI (from the French Le Système International d’Unités), is the modern metric system of measurement. Long the dominant measurement system used in science, the SI is becoming the dominant measurement system used in international commerce. The Omnibus Trade and Competitiveness Act of August 1988 [Public Law (PL) 100-418] changed the name of the National Bureau of Standards (NBS) to the National Institute of Standards and Technology (NIST) and gave to NIST the added task of helping U.S.
    [Show full text]
  • An Introduction to Mass Spectrometry
    An Introduction to Mass Spectrometry by Scott E. Van Bramer Widener University Department of Chemistry One University Place Chester, PA 19013 [email protected] http://science.widener.edu/~svanbram revised: September 2, 1998 © Copyright 1997 TABLE OF CONTENTS INTRODUCTION ........................................................... 4 SAMPLE INTRODUCTION ....................................................5 Direct Vapor Inlet .......................................................5 Gas Chromatography.....................................................5 Liquid Chromatography...................................................6 Direct Insertion Probe ....................................................6 Direct Ionization of Sample ................................................6 IONIZATION TECHNIQUES...................................................6 Electron Ionization .......................................................7 Chemical Ionization ..................................................... 9 Fast Atom Bombardment and Secondary Ion Mass Spectrometry .................10 Atmospheric Pressure Ionization and Electrospray Ionization ....................11 Matrix Assisted Laser Desorption/Ionization ................................ 13 Other Ionization Methods ................................................13 Self-Test #1 ...........................................................14 MASS ANALYZERS .........................................................14 Quadrupole ............................................................15
    [Show full text]
  • Glossary of Terms Used in Photochemistry, 3Rd Edition (IUPAC
    Pure Appl. Chem., Vol. 79, No. 3, pp. 293–465, 2007. doi:10.1351/pac200779030293 © 2007 IUPAC INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY ORGANIC AND BIOMOLECULAR CHEMISTRY DIVISION* SUBCOMMITTEE ON PHOTOCHEMISTRY GLOSSARY OF TERMS USED IN PHOTOCHEMISTRY 3rd EDITION (IUPAC Recommendations 2006) Prepared for publication by S. E. BRASLAVSKY‡ Max-Planck-Institut für Bioanorganische Chemie, Postfach 10 13 65, 45413 Mülheim an der Ruhr, Germany *Membership of the Organic and Biomolecular Chemistry Division Committee during the preparation of this re- port (2003–2006) was as follows: President: T. T. Tidwell (1998–2003), M. Isobe (2002–2005); Vice President: D. StC. Black (1996–2003), V. T. Ivanov (1996–2005); Secretary: G. M. Blackburn (2002–2005); Past President: T. Norin (1996–2003), T. T. Tidwell (1998–2005) (initial date indicates first time elected as Division member). The list of the other Division members can be found in <http://www.iupac.org/divisions/III/members.html>. Membership of the Subcommittee on Photochemistry (2003–2005) was as follows: S. E. Braslavsky (Germany, Chairperson), A. U. Acuña (Spain), T. D. Z. Atvars (Brazil), C. Bohne (Canada), R. Bonneau (France), A. M. Braun (Germany), A. Chibisov (Russia), K. Ghiggino (Australia), A. Kutateladze (USA), H. Lemmetyinen (Finland), M. Litter (Argentina), H. Miyasaka (Japan), M. Olivucci (Italy), D. Phillips (UK), R. O. Rahn (USA), E. San Román (Argentina), N. Serpone (Canada), M. Terazima (Japan). Contributors to the 3rd edition were: A. U. Acuña, W. Adam, F. Amat, D. Armesto, T. D. Z. Atvars, A. Bard, E. Bill, L. O. Björn, C. Bohne, J. Bolton, R. Bonneau, H.
    [Show full text]
  • Millikan Oil Drop Experiment
    (revised 1/23/02) MILLIKAN OIL-DROP EXPERIMENT Advanced Laboratory, Physics 407 University of Wisconsin Madison, Wisconsin 53706 Abstract The charge of the electron is measured using the classic technique of Millikan. Mea- surements are made of the rise and fall times of oil drops illuminated by light from a Helium{Neon laser. A radioactive source is used to enhance the probability that a given drop will change its charge during observation. The emphasis of the experiment is to make an accurate measurement with a full analysis of statistical and systematic errors. Introduction Robert A. Millikan performed a set of experiments which gave two important results: (1) Electric charge is quantized. All electric charges are integral multiples of a unique elementary charge e. (2) The elementary charge was measured and found to have the value e = 1:60 19 × 10− Coulombs. Of these two results, the first is the most significant since it makes an absolute assertion about the nature of matter. We now recognize e as the elementary charge carried by the electron and other elementary particles. More precise measurements have given the value 19 e = (1:60217733 0:00000049) 10− Coulombs ± × The electric charge carried by a particle may be calculated by measuring the force experienced by the particle in an electric field of known strength. Although it is relatively easy to produce a known electric field, the force exerted by such a field on a particle carrying only one or several excess electrons is very small. For example, 14 a field of 1000 volts per cm would exert a force of only 1:6 10− N on a particle × 12 bearing one excess electron.
    [Show full text]
  • Electric Charge
    Electric Charge • Electric charge is a fundamental property of atomic particles – such as electrons and protons • Two types of charge: negative and positive – Electron is negative, proton is positive • Usually object has equal amounts of each type of charge so no net charge • Object is said to be electrically neutral Charged Object • Object has a net charge if two types of charge are not in balance • Object is said to be charged • Net charge is always small compared to the total amount of positive and negative charge contained in an object • The net charge of an isolated system remains constant Law of Electric Charges • Charged objects interact by exerting forces on one another • Law of Charges: Like charges repel, and opposite charges attract • The standard unit (SI) of charge is the Coulomb (C) Electric Properties • Electrical properties of materials such as metals, water, plastic, glass and the human body are due to the structure and electrical nature of atoms • Atoms consist of protons (+), electrons (-), and neutrons (electrically neutral) Atom Schematic view of an atom • Electrically neutral atoms contain equal numbers of protons and electrons Conductors and Insulators • Atoms combine to form solids • Sometimes outermost electrons move about the solid leaving positive ions • These mobile electrons are called conduction electrons • Solids where electrons move freely about are called conductors – metal, body, water • Solids where charge can’t move freely are called insulators – glass, plastic Charging Objects • Only the conduction
    [Show full text]
  • Quantifying the Quantum Stephan Schlamminger Looks at the Origins of the Planck Constant and Its Current Role in Redefining the Kilogram
    measure for measure Quantifying the quantum Stephan Schlamminger looks at the origins of the Planck constant and its current role in redefining the kilogram. child on a swing is an everyday mechanical constant (h) with high precision, measure a approximation of a macroscopic a macroscopic experiment is necessary, force — in A harmonic oscillator. The total energy because the unit of mass, the kilogram, can this case of such a system depends on its amplitude, only be accessed with high precision at the the weight while the frequency of oscillation is, at one-kilogram value through its definition of a mass least for small amplitudes, independent as the mass of the International Prototype m — as of the amplitude. So, it seems that the of the Kilogram (IPK). The IPK is the only the product energy of the system can be adjusted object on Earth whose mass we know for of a current continuously from zero upwards — that is, certain2 — all relative uncertainties increase and a voltage the child can swing at any amplitude. This from thereon. divided by a velocity, is not the case, however, for a microscopic The revised SI, likely to come into mg = UI/v (with g the oscillator, the physics of which is described effect in 2019, is based on fixed numerical Earth’s gravitational by the laws of quantum mechanics. A values, without uncertainties, of seven acceleration). quantum-mechanical swing can change defining constants, three of which are Meanwhile, the its energy only in steps of hν, the product already fixed in the present SI; the four discoveries of the Josephson of the Planck constant and the oscillation additional ones are the elementary and quantum Hall effects frequency — the (energy) quantum of charge and the Planck, led to precise electrical the oscillator.
    [Show full text]
  • The Question of Charge and of Mass
    The question of charge and of mass. Voicu Dolocan Faculty of Physics, University of Bucharest, Bucharest, Romania Abstract. There are two long –range forces in the Universe, electromagnetism and gravity. We have found a general expression for the energy of interaction in these cases, αћc/r, where α is the fine structure constant and r is the distance between the two particles. In the case of electromagnetic interaction we have 2 αћc = e /4πεo, where e is the gauge charge, which is the elementary electron charge. In the case of the gravitational interaction we have αћc = GM2, where M = 1.85×10-9 kg is the gauge mass of the particle. This is a giant particle. A system of like charged giant particles, would be a charged superfluid. By spontaneous breaking of a gauge symmetry are generated the Higgs massive bosons. The unitary gauge assure generation of the neutral massive particles. The perturbation from the unitary gauge generates charged massive particles. Also, the Higgs boson decays into charged and neutral particles. The Tesla coil is the user of the excitations of the vacuum. 1. What is electric charge, and what is mass? According to the Standard Model “ The electric charge is a fundamental conserved property of certain subatomic particles that determines the electromagnetic interactions”. Electrically charged particles are influenced by and create electromagnetic fields. The elementary unit of charge is carried by a single proton and the equivalent negative charge is carried by a single electron. Also, there are up quarks with (2/3)e charge and there are down quarks with (1/3)e- charge.
    [Show full text]
  • Measuring Elementary Charge Currently Accepted Number
    8.11 Electromagnetic Forces 8.11 Electromagnetic Forces 4 The value Millikan and Fletcher measured for elementary charge is slightly smaller than the Measuring Elementary Charge currently accepted number. They used an incorrect value for the viscosity of air. This affected their calculation. The number for elementary charge underwent several revisions. Each time the number became a little bigger. Noted physicist, Richard Feynman, remarked on the way 1 Robert Millikan and Harvey physicists arrived at the currently accepted number. Feynman suggested that physicists Fletcher performed an calculating a value that was significantly larger than Millikan’s thought they were wrong. They experiment to measure the looked for problems in their experiments to explain their “error.” Physicists are subject to bias elementary charge in 1909. just as other humans are. Physicists measuring elementary charge trusted the previously The diagram to the right published results more than their own calculations. One might call this bias “conformity bias.” shows the experimental Conformity bias can be defined as the belief that previously published findings can’t be very far setup. Fine oil mist is off. Conformity bias can be both good and bad. It can lead to more thorough experimentation sprayed into a chamber and analysis. It can also ignore truly novel results. through a nozzle. Friction in the nozzle makes some 5 According to theory, all charge has to be a multiple of the elementary charge, the charge of a droplets become charged. The droplets fall through the chamber into the area between the single electron. More than 100 million additional oil droplets have been measured during the metal plates.
    [Show full text]
  • Ebook, CURENT Could Extend the Outreach Potential of the RET Program
    Energizing Minds of Tomorrow CURENTCENTER FOR ULTRA-WIDE -AREA RESILIENT ELECTRIC ENERGY TRANSMISSION NETWORKS VOLUME ONE: K- 5 ENERGY SCIENCE ACTIVITES The interdisciplinary elements within this publication serve to supplement teaching STEM concepts focused on power and energy systems for elementary educators. CURENT Energizing Minds of Tomorrow VOLUME ONE: K- 5 Energy Science Activities EDITORS: FELICIA QUALLS CHIEN- FEI CHEN ANNE SKUTNIK CURENT is a National Science Foundation and U.S. Department of Energy funded Engineering Research Center. For more information about the Center for Ultra-Wide-Area Resilient Electric Energy Transmission Networks (CURENT) or our education and outreach programming, please contact: CURENT Engineering Research Center 555 Min H. Kao Building 1520 Middle Drive Knoxville, TN 37996-2250 Tel: 865-974-9720 Fax: 865-974-9723 Email: [email protected] https://curent.org The lessons in this e-book were produced by several cohorts in CURENT’s Research Experience for Teachers (RET) program. Use of CURENT materials for public education efforts and non-commercial purposes is strongly encouraged and requires no expressed authorization. It is requested, however, that any such use properly attributes the source as: "Courtesy of CURENT Engineering Research Center" or "Courtesy of CURENT, an engineering research cooperation between the NSF and the DOE." Images owned by individual photographers and artists are so noted on the pages where they appear. These images may have a Copyright © with all rights reserved of the creator. If you wish to use them, contact the individual owner. All images and text not credited otherwise are Copyright © 2017 Center for Ultra-Wide-Area Resilient Electric Energy Transmission Networks.
    [Show full text]
  • Physical Setting/Physics Core Curriculum Was Reviewed by Many Teachers and Administrators Across the State
    PhysicalPhysical Setting/Setting/ PhysicsPhysics Core Curriculum THE UNIVERSITY OF THE STATE OF NEW YORK THE STATE EDUCATION DEPARTMENT http://www.emsc.nysed.gov THE UNIVERSITY OF THE STATE OF NEW YORK Regents of The University CARL T. HAYDEN, Chancellor, A.B., J.D. ............................................................................Elmira ADELAIDE L. SANFORD, Vice Chancellor, B.A., M.A., P.D. .................................................Hollis DIANE O’NEILL MCGIVERN, B.S.N., M.A., Ph.D. ..............................................................Staten Island SAUL B. COHEN, B.A., M.A., Ph.D. .....................................................................................New Rochelle JAMES C. DAWSON, A.A., B.A., M.S., Ph.D. .......................................................................Peru ROBERT M. BENNETT, B.A., M.S. ........................................................................................Tonawanda ROBERT M. JOHNSON, B.S., J.D. .........................................................................................Huntington ANTHONY S. BOTTAR, B.A., J.D. .........................................................................................North Syracuse MERRYL H. TISCH, B.A., M.A. ............................................................................................New York ENA L. FARLEY, B.A., M.A., Ph.D. .....................................................................................Brockport GERALDINE D. CHAPEY, B.A., M.A., Ed.D...........................................................................Belle
    [Show full text]
  • Charge Watch Edpuzzle Video: Electric Charge, Law of Charges, and Quantization of Charge Lecture Notes
    Name: ____________________ Week 1 - Electrostatics Day 1 – Charge Watch Edpuzzle Video: Electric Charge, Law of Charges, and Quantization of Charge Lecture Notes: https://tinyurl.com/rdmshxj How many types of electric charge are there? What are their names? Can an object have all of one type of charge? How can an object have a charge? Explain when charges either attract or repel? (Law of Charges) Explain the “Quantization” of electric charges. What do we call an atom that has a net electric charge? How can an atom become positive? Negative? The charge on an electron or on a proton has a magnitude of 1.6 × 10–19 C, where “C” are units of charge called “coulombs”. Of the numbers below, circle the numbers that represent amounts of charge that you CAN have. 7.0 × 10–19 C 4.0 × 10–19 C 8.8 × 10–19 C 4.8 × 10–19 C 2.4 × 10–19 C 6.4 × 10–19 C 3.2 × 10–19 C 8.0 × 10–19 C Look this up on the Internet: What does the “Law of Conservation of Charge” say? Do not use the words “created” or “destroyed”. Flipping Physics Lecture Notes: Electric Charge https://www.flippingphysics.com/charge.html The Law of Charges: • Like charges repel & • Unlike charges attract When we rub fur against a rubber rod and then a rubber balloon, electrons transfer from the fur to the rubber objects leaving the rubber objects with a net negative charge and the fur with a net positive charge. When we rub silk against a glass rod, electrons transfer from the glass rod to the silk leaving the glass rod with a net positive charge and the silk with a net negative charge.
    [Show full text]