2. 8/26/20151 Chemistry 4362 Advanced Inorganic Chemistry Dr. Byron K. Christmas Instructor: Dr. Byron K. Christmas Tue & Thur - 5:29 to 6:49 p.m. Class Time: Tue & Thur - 5:29 to 6:49 p.m. N-936  C-320 Classroom: N-936  C-320 (713) 221-8169(713) 221-8528 Phone: (713) 221-8169FAX: (713) 221-8528 ChristmasB@uhd.edu E-Mail: ChristmasB@uhd.edu

3. 8/26/20152 Introduction What is Inorganic Chemistry ? “The chemistry of everything everything that is NOT NOT organic…” “The chemistry of all of the elements and their compounds “The chemistry of all of the elements and their compounds except for the hydrocarbons and their derivatives.” except for the hydrocarbons and their derivatives.” “The branch of chemistry falling between and overlapping “The branch of chemistry falling between and overlapping with physical chemistry and organic chemistry.” with physical chemistry and organic chemistry.” “What Inorganic Chemists Do!” “What Inorganic Chemists Do!” Your Personal Definition??

4. 8/26/20153 What Do Inorganic Chemists Do ? Synthesize and characterize substances other than those that are clearly “organic”.Synthesize and characterize substances other than those that are clearly “organic”. Determine the structures of inorganic substances. Determine the structures of inorganic substances. Investigate the chemical reactions of inorganic substances. Investigate the chemical reactions of inorganic substances. Investigate the physical properties of inorganic substances. Investigate the physical properties of inorganic substances.. Develop hypotheses and theories to explain and systematize Develop hypotheses and theories to explain and systematize the empirical data collected. the empirical data collected.

5. 8/26/20154 Why Should You Study Inorganic Chemistry ? Essentially the entire universe is Inorganic.Essentially the entire universe is Inorganic. Elemental Composition of the Sun and the Universe SunUniverse Hydrogen92.5 % 90.87 % Helium 7.3 % 9.08 % All Others 0.2 % 0.05 % The Earth is predominantly Inorganic The Earth is predominantly Inorganic. Elemental Composition of the Earth’s Crust Oxygen45.5 %Iron6.20 % Silicon27.2 %Calcium4.66 % Aluminum 8.30 %All Others8.14 %

6. 8/26/20155 Inorganic materials are an essential part of our national economy. Inorganic materials are an essential part of our national economy. U.S. Production of Top 10 Chemicals (x 10 9 lb.) - 1997 Sulfuric Acid95.58 Nitrogen82.88* Oxygen64.84* Ethylene51.08 Lime42.56 Ammonia38.39 Propylene27.53 Phosphoric Acid26.83 Ethylene Dichloride26.29 Sulfur26.24 From C&EN, June 29, 1998 *Calculated from “billion cubic feet at STP”

7. 8/26/20156 2000 RANK (by mass) CHEMICAL2000 PRODUCTION (in 10 9 kg) FORMULAPRODUCTION (in moles) RANK (by moles) 1Sulfuric acid39.62 2Ethylene25.15 3Lime20.12 4Phosphoric acid16.16 5Ammonia15.03 6Propylene14.45 7Chlorine12.01 8Sodium hydroxide10.99 9Sodium carbonate10.21 10Ethylene chloride9.92 11Nitric acid7.99 12Ammonium nitrate7.49 13Urea6.96 14Ethylbenzene5.97 15Styrene5.41 16Hydrogen chloride4.34 17Ethylene oxide3.87 18Cumene3.74 19Ammonium sulfate2.60 201,3-Butadiene2.01 http://scifun.chem.wisc.edu/chemweek/Sulf&top/Sulf&Top.html

8. 8/26/20157 U.S. Production of Top 50 Chemicals (x 10 9 lb.) - 1994 Total Organics279.17 Total Inorganics450.19 Grand Total729.36 Inorganics are essential to life. Inorganics are essential to life. q Water is essential for all life. q About 30 different elements are believed to be essential to life - 28 in addition to carbon and essential to life - 28 in addition to carbon and hydrogen. hydrogen. For all practical purposes, Inorganic Chemistry IS For all practical purposes, Inorganic Chemistry IS chemistry - the study of the properties, composition, and structure of matter, the physical and chemical changes it undergoes, and the energy liberated or absorbed during those changes. chemistry - the study of the properties, composition, and structure of matter, the physical and chemical changes it undergoes, and the energy liberated or absorbed during those changes.

9. 8/26/20158 Approaches to the Study of Inorganic Chemistry Empirical Approach (Descriptive Chemistry) Empirical Approach (Descriptive Chemistry) q Historically this was the way it was taught. q It involves essentially all memorization. q It is necessary for a complete understanding of Chemistry. Theoretical Approach Theoretical Approach q It provides a framework for understanding the “why” of descriptive chemistry. q It can provide “intellectual satisfaction”. q It is limited in its ability to give explanations for all observed phenomena. q It has dominated the teaching of Inorganic Chemistry for over 30 years.

10. 8/26/2015 9 Introduction to Descriptive Chemistry Definition: Definition: “…the study of the composition, structure, facts about the and properties of matter….” - the facts about the elements and their compounds. Comments from the Experts: Comments from the Experts: “…evident differences between this and previous editions…is the absence of much theoretical material previously included…the continuing rapid growth of chemistry…required the addition of impor- facts tant new facts to all of the descriptive material…over the years, become less persuaded of the value of certain types of facts theorizing….Thus, we felt obliged to make space for facts at Cotton and Wilkinson, the expense of theoretical material.” Cotton and Wilkinson, Advanced Inorganic Chemistry, 5th Edition, 1988.

11. 8/26/2015 10 Comments from the Experts: Comments from the Experts: “The facts concerning the properties and reactions of substances are the very essence of chemistry. Facts undergo little if any change in contrast to constantly changing theories. Moreover, …a chemist needs a solid background of facts in order to appreciate the need for theories….” R. J. Gillespie in the Forward of Chemistry of the Elements, Greenwood and Earnshaw, 1st Edition, 1984.

12. 8/26/2015 11 “Over the years, the theoretical part tended to grow at the expense of the descriptive material….The theoretical part tended to become the end rather than the means….By the 1970’s many teachers had to abandon any attempt to cover descriptive inorganic chemistry in the traditional sense. Thus we can encounter the student who can write an erudite account of structural minutiae in copper(II) chemistry, ligand field spectra and…,but who knows little about the more mundane compounds of the transition elements and would be hard pressed to locate indium in the Periodic Table, let Derek W. Smith, alone venture anything about its chemistry.” Derek W. Smith, Inorganic Substances: A Prelude to the Study of Descriptive Inorganic Chemistry, 1st Edition, 1990.

13. 8/26/2015 12 “Chemistry has always been, and still is, a practical subject….An American professor told me he divided inorganic chemistry books into two types: theoretical and practical. In deciding how to classify any particular book, he first looked to see if the extraction of the two most produced metals (Fe and Al) was adequately covered, what impurities were likely to be present, and how the processing was adapted to re- move them. Second, he looked to see if the treatment of the bonding in xenon compounds and ferrocene was longer than that of the pro- duction of ammonia. Third, he looked to see if the production and uses of phosphates were covered adequately….For some years there has been a trend for chemistry teaching to become more theoretical. There is always theoretical interest in another interesting oxidation state or another unusual complex, but the balance of this book is tilted to ensure that they do not exclude the commonplace, the mun- J. D. Lee, Concise Inorganic dane and the commercially important.” J. D. Lee, Concise Inorganic Chemistry, 5th Edition, 1996.

14. 8/26/201513 Industrial Applications Approach Industrial Applications Approach q Few schools other than chemical engineering programs have used this approach. q It is of great “practical” importance for students preparing for industry. q It is of limited utility in preparing for graduate work in chemistry. Balanced Approach Balanced Approach q Provides a balance among all approaches. q Applicable to “survey-type” course. q Useful for either graduate school or industry preparation. q Used in THIS COURSE!!

15. 8/26/201514 Course Overview Introduction to Inorganic Polymers Introduction to Inorganic Polymers Theoretical Concepts Theoretical Concepts qAtomic Structure & the Periodic Table q Properties of the Elements q Introduction to Chemical Bonding q The Covalent Bond q The Metallic Bond q The Ionic Bond q Intermolecular Attractive Forces q Inorganic Thermodynamics and Kinetics q Solvent Systems and Acids and Bases q Oxidation/Reduction Descriptive Chemistry and Industrial Applications Descriptive Chemistry and Industrial Applications Student Presentations Student Presentations

16. 8/26/201515 Introduction to Inorganic Polymers (Page 338 in Text) Questions to Ponder: 1. Would you know an Inorganic Polymer if you saw one? 2. How could you determine if an inorganic material was, in fact, “polymeric”? 3. List important types of Inorganic Polymers. 4. How would you determine what is and what is NOT an Inorganic Polymer? Is NaCl a Polymer? Is Graphite a Polymer? What about Diamond? Is Aluminum a Polymer? What about Window Glass? 5. What general principles of chemical bonding, atomic size, etc. lead to effective polymer formation for different types of elements? 6. What are commercially important inorganic polymers?

17. 8/26/201516 Introduction to Inorganic Polymers Catenation – What are the requirements? Valence of two or more? Valence of two or more? Bond energies? Bond energies? What else? What else?HomocatenationHeterocatenation Bond Energies – kJ/mole C-C356 Si-Si222 Ge-Ge188 Sn-Sn167 Pb-Pb 87 S-S251 P-P201 O-O142 Si-O460 Sn-O544 Al-O586 Si-N355 B-N460 Bond D (kJ/mol) r (pm) Si-Si222233 Si-N355 Si-O452163 Si-S293200 Si-F565160 Si-Cl381202 Si-Br310215 Si-I234243 Ge-Ge188241 Ge-N257 Ge-F470168 Ge-Cl349210 Ge-Br276230 Ge-I212 Sn-F414 Sn-Cl323233 Sn-Br273250 Sn-I205270 Pb-F331 Pb-Cl243242 Pb-Br201 Pb-I142279 http://chemviz.ncsa.uiuc.edu/content/doc-resources-bond.html

18. 8/26/201517 Introduction to Inorganic Polymers Questions?Assignments! Study Hand-outs and your text on Inorganic Polymers Find three to five ADDITIONAL references on the Web and study them and study them Prepare for next Thursday’s Silicone laboratory (Page 176 in Lab Manual) Polysulfide Demonstration/Experiment

19. 8/26/201518 Theoretical Concepts Chapter 1 qAtomic Structure & the Periodic Table qProperties of the Elements q Introduction to Chemical Bonding q The Ionic Bond q The Covalent Bond q The Metallic Bond q Intermolecular Attractive Forces q Thermodynamics q Acids and Bases q Oxidation/Reduction

20. 8/26/201519 ATOMIC STRUCTURE Definition of Chemistry: The study of the properties, composition, and STRUCTURE STRUCTURE of matter, the physical and chemical changes it undergoes, and the energy liberated or absorbed during those changes. STRUCTURE The foundation for the STRUCTURE of inorganic STRUCTURE materials is found in the STRUCTURE of the atom. Atomic Structure Molecular Structure Bulk Structure Material Properties

21. 8/26/201520 ATOMIC STRUCTURE Historical Development: Greek Concepts of Matter Aristotle - Matter is continuous, infinitely divisible, and is composed of only 4 elements: Earth, Air, Fire, and Water q Won the philosophical/political battle. q Dominated Western Thought for Centuries. q Seemed very “logical”. WRONG!! q Was totally WRONG!!

22. 8/26/201521 ATOMIC STRUCTURE Democritus The “Atomists” (Democritus, Lucippus, Epicurus, et. al.) - Matter consists ultimately of “indivisible” particles called “atomos” that canNOT be further subdivided or simplified. If these “atoms” had space between them, nothing was in that space - the “void”. q Lost the philosophical/political battle. q Lost to Western Thought until 1417. q Incapable of being tested or verified. q Believed the “four elements” consisted of “transmutable” atoms. q Was a far more accurate, though quite imperfect “picture” of reality.

23. 8/26/201522 ATOMIC STRUCTURE Modern Concepts of Matter John Dalton (1803) - An atomist who formalized the idea of the atom into a viable scientific theory in order to explain a large amount of empirical data that could not be explained otherwise. q Matter is composed of small “indivisible” particles called “atoms”. q The atoms of each element are identical to each other in mass but different from the atoms of other elements. q A compound contains atoms of two or more elements bound together in fixed proportions by mass.

24. 8/26/201523 ATOMIC STRUCTURE q A chemical reaction involves a rearrangement of of atoms but atoms are not created nor destroyed during such reactions. Present Concepts - An atom is an electrically neutral entity consisting of negatively charged electrons (e - ) situated outside of a dense, posi- tively charged nucleus consisting of positively charged protons (p + ) and neutral neutrons (n 0 ). ParticleCharge Mass Electron - 1 9.109 x 10 -28 g Proton +1 1.673 x 10 -24 g Neutron 0 1.675 x 10 -24 g

25. 8/26/201524 ATOMIC STRUCTURE e-e- p+nop+no n o p+p+ Nucleus Electron Cloud Model of a Helium-4 (4He) atom How did we get this concept? - This portion of our program is brought to you by: Democritus, Dalton, Thompson, Planck, Einstein, Millikan, Rutherford, Bohr, de Broglie, Heisenberg, Schrödinger, Chadwick, and many others.

26. 8/26/201525 ATOMIC STRUCTURE Democritus - First atomic ideas Dalton - 1803 - First Atomic Theory J. J. Thompson - 1890s - Measured the charge/mass ratio of the electron (Cathode Rays) + Anode _ Cathode Electric Field Source (Off) Fluorescent Material With the electric field off, the cathode ray is not deflected.

27. 8/26/201526 ATOMIC STRUCTURE Cathode Anode Electric Field Source (On) Fluorescent Material - ++ - With the electric field on, the cathode ray is deflected away from the negative plate. The stronger the electric field, the greater the amount of deflection. Cathode Anode - + Magnet

28. 8/26/201527 ATOMIC STRUCTURE With the magnetic field present, the cathode ray is deflected out of the magnetic field. The stronger the magnetic field, the greater the amount of deflection. e/m = E/H 2 r e = the charge on the electron m = the mass of the electron E = the electric field strength H = the magnetic field strength r = the radius of curvature of the electron beam Thompson, thus, measured the charge/mass ratio of the electron - 1.759 x 10 8 C/g

29. 8/26/201528 ATOMIC STRUCTURE Summary of Thompson’s Findings: q Cathode rays had the same properties no matter what metal was being used. what metal was being used. q Cathode rays appeared to be a constituent of all matter and, thus, appeared to be a “sub-atomic” matter and, thus, appeared to be a “sub-atomic” particle. particle. q Cathode rays had a negative charge. q Cathode rays have a charge-to-mass ratio of 1.7588 x 10 8 C/g. of 1.7588 x 10 8 C/g.

30. 8/26/201529 ATOMIC STRUCTURE R. A. Millikan - Measured the charge of the electron. In his famous “oil-drop” experiment, Millikan was able to determine the charge on the electron independently of its mass. Then using Thompson’s charge-to-mass ratio, he was able to calculate the mass of the electron. e = 1.602 10 x 10 -19 coulomb e/m = 1.7588 x 10 8 coulomb/gram m = 9.1091 x 10 -28 gram Goldstein - Conducted “positive” ray experiments that lead to the identification of the proton. The charge was found to be identical to that of the electron and 1.6726 x 10 -24 g. the mass was found to be 1.6726 x 10 -24 g.

31. 8/26/201530 ATOMIC STRUCTURE Ernest Rutherford - Developed the “nuclear” model of the atom. The Plum Pudding Model of the atom: - - - - - + + + + + + + + + +A smeared out “pudding” of positive charge with negative electron “plums” imbedded in it. The Metal Foil Experiments: Radioactive Material in Pb box. Metal Foil Fluorescent Screen -particles

32. 8/26/201531 ATOMIC STRUCTURE If the plum pudding model is correct, then all of the massive  -particles should pass right through without being deflected. In fact, most of the  - particles DID pass right through. However, a few of them were deflected at high angles, disproving the “plum pudding” model. Rutherford concluded from this that the atom con- sisted of a very dense nucleus containing all of the positive charge and most of the mass surrounded by electrons that orbited around the nucleus much as the planets orbit around the sun.

33. 8/26/201532 ATOMIC STRUCTURE Assignment: Assume the diameter of the nucleus of a hydrogen atom is 1 x 10 -13 cm and the diameter of the atom is 1 x 10 -8 cm. 1. Calculate the volume of the nucleus and the volume of the atom in cm 3. 2. Calculate the volume of empty space in the atom. 3. Calculate the ratio of the volume of the nucleus to volume of the whole atom. 4. Calculate the density of the nucleus if the proton’s mass is 1.6726 x 10 -24 g

34. 8/26/201533 ATOMIC STRUCTURE Problems with the Rutherford Model: It was known from experiment and electromagnetic theory that when charges are accelerated, they continuously emit radiation, i.e., they loose energy continuously. The “orbiting” electrons in the atom were, obviously, not doing this. q The atoms were NOT collapsing. q Atomic spectra and blackbody radiation were known to be DIS DIScontinuous.

35. 8/26/201534 ATOMIC STRUCTURE Atomic Spectra - Since the 19th century, it had been known that when elements and compounds are heated until they emit light (glow) they emit that light only at discrete frequencies, giving a line spectrum. + - Hydrogen Gas Line Spectrum

36. 8/26/201535 ATOMIC STRUCTURE When white light is passed through a sample of the vapor of a substance, only discrete frequencies are absorbed, giving an absorption ban spectrum. These frequencies are identical to those of the line spectrum of the same element or compound. For hydrogen, the spectroscopists of the 19th Century found that the lines were related by the Rydberg equation:  c = R[(1/m 2 ) - (1/n 2 )]  frequency c = speed of light R = Rydberg Constant m = 1, 2, 3, …. n = (m+1), (m+2), (m+3), ….

37. 8/26/201536 ATOMIC STRUCTURE Max Planck - In 1900 he was investigating the nature of black body radiation and tried to interpret his findings using accepted theories of electromagnetic radiation (light). He was NOT successful since these theories were based on the assumption that light had WAVE WAVE characteristics. To solve the problem he postulated that light was emitted from black bodies in discrete packets he called “quanta”. Einstein later called them “photons”. By assuming that the atoms of the black body emitted energy only at discrete frequencies, he was able to explain black body radiation. E = h E = h

38. 8/26/201537 ATOMIC STRUCTURE Both spectroscopy and black body radiation indicated that atoms emitted energy only at discrete frequencies or energies rather than continuously. Is light a particle or a wave?? Why do atoms emit only discrete energies? What actually happens when light interacts with matter? What was wrong with Rutherford’s Model?

39. 8/26/201538 ATOMIC STRUCTURE Niels Bohr - Bohr corrected Rutherford’s model of the atom by formulating the following postulates: q Electrons in atoms move only in discrete orbits around the nucleus. q When in an orbit, the electron does NOT emit energy. q They may move from one orbit to another but are NEVER residing in between orbits. q When an electron moves from one orbit to another, it absorbs or emits a photon of light with a specific energy that depends on the difference in energy between the two orbits.

40. 8/26/201539 ATOMIC STRUCTURE + Lyman Series Balmer Series Paschen Series The Bohr Model of the Atom (Visible) (IR) (UV)

41. 8/26/201540 ATOMIC STRUCTURE q The lowest possible energy state for an electron GROUND STATE is called the GROUND STATE. All other states EXCITED STATES are called EXCITED STATES. E n = (- 2.179 x 10 -18 J)/n 2 E photon = E high - E low E photon = [(- 2.179 x 10 -18 J)/n 2 high ] -[(- 2.179 x 10 -18 J)/n 2 low ] -[(- 2.179 x 10 -18 J)/n 2 low ] = - 2.179 x 10 -18 J[(1/n 2 high ) - (1/n 2 low )] = - 2.179 x 10 -18 J[(1/n 2 high ) - (1/n 2 low )] Does this equation look familiar?  c = R[(1/m 2 ) - (1/n 2 )]

42. 8/26/201541 ATOMIC STRUCTURE Niels Bohr won the Nobel Prize for his work. However, the model only worked perfectly for What about all of those other elements?? hydrogen. What about all of those other elements?? Louis de Broglie - Thought that if light, which was thought to have wave characteristics, could also have particle characteristics, then perhaps electrons, which were thought to be particles, could have characteristics of waves.  h/mv An electron in an atom was a “standing wave”!

43. 8/26/201542 ATOMIC STRUCTURE Werner Heisenberg - Developed the “uncertainty” It is impossible to make simultaneous and principle: It is impossible to make simultaneous and exact measurements of both the position (location) and the momentum of a sub-atomic particle such as an electron. (  x)(  p)  h/2  Our knowledge of the inner workings of atoms and molecules must be based on probabilities rather than on absolute certainties.

44. 8/26/201543 ATOMIC STRUCTURE Erwin Schrödinger - Developed a form of quantum mechanics known as “wave mechanics”. H  E  H = Hamiltonian operator E = Total energy of the system  Wave function [(-h 2 )/(8  2 m)]  2  - [e 2 /r]  = E  This is simply a quantum mechanical statement of the Law of Conservation of Energy Kinetic Energy Term Potential Energy Term

45. 8/26/201544 ATOMIC STRUCTURE Of the numerous solutions to the Schrödinger equation for hydrogen, only certain ones are allowed due to the following boundary conditions:  , the wave function, must be continuous and finite. q It must be single-valued at all points (There can’t be two different probabilities of finding an electron at one point in space).  The probability of finding the electron,  2, somewhere in space must = 1.  -  ++  2 dxdydz = 1 Y has many values that meet these conditions. They are called “orbitals”.

46. 8/26/201545 ATOMIC STRUCTURE Wave Function - A mathematical function associated with each possible state of an electron in an atom or molecule. q It can be used to calculate the energy of an electron in the state q the average and most probable distance from the nucleus q the probability of finding the electron in any specified region of space.

47. 8/26/201546 ATOMIC STRUCTURE Quantum Numbers: Principle Quantum Number, n - Principle Quantum Number, n - An integer greater than zero that represents the principle energy level or “shell” that an electron occupies. Energy# of orbitals nLevelShelln 2 1 1st K1 2 2nd L2 3 3rd M9 4 4th N 16 etc. etc. etc.etc.

48. 8/26/201547 ATOMIC STRUCTURE Azimuthal Quantum Number, l - Azimuthal Quantum Number, l - The quantum number that designates the “subshell” an electron occupies. It is an indicator of the shape of an orbital 0 to n-1 in the subshell. It has integer values from 0 to n-1. l = 0, 1, 2, 3, …, n - 1 s p d f Magnetic Quantum Number, m l - Magnetic Quantum Number, m l - The quantum number that determines the behavior of an electron the orbital in a magnetic field. It designates the orbital and -l to +l including 0 has integer values from -l to +l including 0. ml ml ml ml = -l, …, -3, -2, -1, 0, +1, +2, +3, …, +l

49. 8/26/201548 ATOMIC STRUCTURE Orbital# of nl Name m l Orbitals 10 1s 0 1 20 2s 0 1 1 2p -1, 0, +1 3 1 2p -1, 0, +1 3 30 3s 0 1 1 3p -1, 0, +1 3 1 3p -1, 0, +1 3 2 3d-2, -1, 0, +1, +2 5 etc.etc. etc. etc. etc. Spin Quantum Number, ms ms ms ms - The quantum number that designates the orientation of an electron in a magnetic field. It has half-integer values, +½ or -½.

50. 8/26/201549 ATOMIC STRUCTURE So what do atoms look like? probability A. Interpretation of  : The probability of finding an electron in a small volume of space centered around some point is proportional to the value of    at that point. B. Electron Probability Density vs. r C. Dot Density Representation: Imagine super- imposing millions of photographs taken of an electron in rapid succession. D. Radial Densities

51. 8/26/201550 Electron Configuration A. Many-electron atom: An atom that contains two or more electrons. B. Problems with the Bohr model: 1. It “assumed” quantization of the energy levels in hydrogen. 2. It failed to describe or predict the spectra of more complicated atoms. ATOMIC STRUCTURE

52. 8/26/201551 C. What are the differences in electron energy levels in hydrogen vs. more complicated atoms? 1s 2s 2p 3s 3p 3d Ground State Hydrogen Atom ATOMIC STRUCTURE

53. 8/26/201552 H 1s 2s 2p Li 1s 2s 2p Splitting of the Degeneracy ATOMIC STRUCTURE

54. 8/26/201553 1. In hydrogen, all subshells and orbitals in a given principal energy level have the same energy. Degenerate They are said to be Degenerate. 2. In many-electron atoms, s-orbitals have lower energy than p-orbitals which have lower energy than d-orbitals which have lower energy than f-orbitals, etc., etc. 3. Reason: Complex electrostatic interactions. Splitting of the Degeneracy ATOMIC STRUCTURE

55. 8/26/201554 + - Hydrogen ++ -- Helium +++ Lithium -- - A. Shielding Effect - A decrease in the nuclear force of attraction for an electron caused by the presence of other electrons in underlying orbitals. B. Effective Nuclear Charge - A positive charge that may be less than the atomic number. It is the charge “felt” by outer electrons due to shielding by electrons in underlying orbitals.

56. 8/26/201555 No two electron in The Pauli Exclusion Principle - No two electron in the same atom can have the same four quantum numbers. H + e -  H - QuantumElectron 1Electron 2 Number n11 l00 mlmlmlml00 msmsmsms +1/2 -1/2 ATOMIC STRUCTURE

57. 8/26/201556 The Aufbau Principle - A procedure for “building up” the electronic configuration of many-electron atoms wherein each electron is added consecutively to the lowest energy orbital available, taking into account the Pauli exclusion principle. Order of Filling - 1s2s2p3s3p4s3d4p5s Increasing Energy 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 5g

58. 8/26/201557 Designating Electron Configurations - Standard Designation q Standard Designation H1s1 He1s2 Li1s2 2s1 Be1s2 2s2 B 1 s2 2s2 2p1 C 1s2 2s2 2p2 q Orbital Diagram Designation H He 1s Li Be 1s 2s B C 1s 2s 2p

59. 8/26/201558 q Core Designation - q Core Designation - A designation of electronic configuration wherein the outer shell electrons are shown along with the “core” configuration of the closest previous noble gas. Li Na K Rb Be Mg Ca Sr [He] 2s 1 [Ne] 3s 1 [Ar] 4s 1 [Kr] 5s 1 [He] 2s 2 [Ne] 3s 2 [Ar] 4s 2 [Kr] 5s 2

60. 8/26/201559 Hund’s Rule of Maximum Multiplicity - Electrons occupy a given subshell singly and with parallel spins until each orbital in the subshell has one electron. “Electrons try to stay as far apart as possible” q Elevator Analogy q Bus Seat Analogy B C N [He] 2s 2 2p 1 [He] [He] 2s 2 2p 2 [He] 2s 2 2p 3 2s2p

61. 8/26/201560 Assignment: Write the electron configuration using all three types of designation for lead (Pb). Electronic Configuration for postive ions (cations) - Cations are formed by removing electrons in order nn of decreasing n value. Electrons with the same n l value are removed in order of decreasing l value. Pb [Xe] 6s 2 6s 2 4f 14 4f 14 5d 10 5d 10 6p 2 Pb 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p2

62. 8/26/201561 Assignment: What are the electron configurations for Fe 2+ Fe 3+ CrCr 3+ Se 2- ? Questions?