Chapter 6: Electronic Structure of AtomsChapter 6: Electronic Structure of AtomsConcept CheckWhy do Orbital Energies Differ? (Quantitatively)Energies of Orbitals: Many Electron AtomsElectron “spin”The Fourth Quantum Number (ms)Pauli Exclusion PrincipleWhy Does the Periodic Table Look Like it Does?Hunds RulePractice ProblemElectron Configurations (Memorize?)More Electron ConfigurationsElectron Configuration and the Periodic TableElectron Configurations of the ElementsPractice ProblemPractice with Electron ConfigurationsThe d-Shell ExceptionsWhat You Should KnowWhat You Should KnowChapter 6: Electronic Structure of AtomsCH110 FA11 SAS 1Prepare for Recitation September 8thALEKS Objective 2 due September 6thANGEL Quiz 2, September 8thLecture 5: August 31stLecture 6: September 2ndLabor Day Holiday: September 5thYou are advised to re-read Ch. 6.1-6.6 in addition tothe work shown below in order to help you see thebig picture for this section of the course.Read: Ch. 6.7 – 6.9Additional Preparation*: BLB 6: 33,39,54; Packet 6: 6-9*ALEKS work is necessary but not sufficient for exam level preparation! Do not neglect the packet!Chapter 6: Electronic Structure of AtomsCH110 FA11 SAS 2By the end of Today’s Lecture you should know:wavelength and frequency of light, dual nature of light, electronic transitions and line spectraBohr modelMatter acts as wavesHeisenberg Uncertainty PrincipleElectronic transitions of orbitalsQuantum numbers (n, , m, ms)Orbitals: their shapes and energiesOrbitals and atoms with many electronsSpin quantum number (ms): Pauli Exclusion Principle and Hunds RuleElectron Configurations using the periodic tableWhat is the structure of an atom?What are the properties of atoms?Remember: structure affects function!Where are the electrons located? What is the energy of an electron?KEY QUESTIONS: THE BIG PICTUREConcept CheckCH110 FA11 SAS 3Understanding electromagnetic energy led toquantum theory(it explains what we observe) which led toatomic structureand predictselectron configurationsand explainsperiodic trends of the elementsWhy do Orbital Energies Differ?(Quantitatively)CH110 FA11 SAS 4Electrons in inner orbitals act as screens for outer electrons. Outer electrons experience a lesser nuclear charge (less attractionGeneral Trends in ScreeningFor a given shell (defined by __)•s orbital has electron density at nucleus (sees larger Zeff) and _________________•p orbital has no electron density at the nucleus and __________________•screening increases:E increases:Energies of Orbitals:Many Electron AtomsCH110 FA11 SAS 5Questions we haven’t answered yet:How do the electrons fill the orbitals? In what order? How many electrons can go into an orbital?Electron “spin”CH110 FA11 SAS 6Stern-Gerlach experiment• neutral atoms (electrons) seem to possess magnetic moment that is quantized• enter… another quantum number• spin magnetic quantum number:The Fourth Quantum Number (ms)CH110 FA11 SAS 7• Electron has spin (_________________)as if it had north and south poles• Confirmed by Experiment!ms=Electrons have 4 quantum numbersn l mlmsdefine orbitalmshas only 2 spin values and no two e-can have the same 4 quantum numbers!Therefore, max of 2 electrons per orbitalPauli Exclusion PrincipleWolfgang Pauli, 1945 Nobel Prize in PhysicsPauli Exclusion PrincipleCH110 FA11 SAS 8• No two electrons in an atom can havethe same four quantum numbers• Electrons in the same orbital have thesame values for the first three quantumnumbers• mscan have only two values:•An orbital can hold only two electrons. Subshell No. of Orbitals Max. No. of e–s (l = 0) p (l = 1) d (l = 2)f (l = 3)Look at the periodic table!Why Does the Periodic Table Look Like it Does?CH110 FA11 SAS 9Because of the Pauli Exclusion Principle!The Aufbau Principle:H LiHe BeBCHunds RuleCH110 FA11 SAS 10• How do we fill orbitals of equal energy (same _______ ) with electrons? • How do we handle msof the electrons?Carbon 6 electrons1s22s22p2Why? How do you keep electrons apart (which minimizes their energy)?Practice ProblemCH110 FA11 SAS 11Fill in the following table in accordance with Hunds Rule:1s 2s 2p 3sCNONeNaElectron Configurations (Memorize?)CH110 FA11 SAS 12• Orbitals are filled by electrons insequence determined by energyH 1sHe 1s2Li 1s22s ← new row of Periodic TableBe 1s22s2B 1s22s22pC 1s22s22p2N 1s22s22p3O 1s22s22p4F 1s22s22p5Ne 1s22s22p6 Na 1s22s22p63s ← new row of PTMg 1s22s22p63s2More Electron ConfigurationsCH110 FA11 SAS13Ne 1s22s22p6 Na (Ne)3s ← new row of PTMg (Ne)3s2Al (Ne)3s23pSi (Ne)3s23p2P (Ne)3s23p3S (Ne)3s23p4Cl (Ne)3s23p5Ar (Ne)3s23p6K (Ar)4s ← new row of PTCa (Ar)4s2Sc (Ar)4s23dTi (Ar)4s23d2V (Ar)4s23d3Cr (Ar)4s13d5Mn (Ar)4s23d5Fe (Ar)4s23d6Co (Ar)4s23d7Ni (Ar)4s23d8Cu (Ar)4s13d10Zn (Ar)4s23d10transitionmetals← filled shellElectron Configuration and the Periodic TableCH110 FA11 SAS 14• Location on the periodic table is related to electron configuration .• Elements in the same column (family) have the same _____________ configuration.Example: alkali metals (column 1) have whatvalence electron configuration?(H)Li [He]Na [Ne]K [Ar]Rb [Kr]Cs [Xe]• halogens (F, Cl, Br, I) have _______ outer shell• noble gases (inert) have filled outer shell of _______Valence electrons determine the chemistry!Electron Configurations of the ElementsCH110 FA11 SAS 15Practice ProblemCH110 FA11 SAS 16Which of the following electron configurations can be ruled out by the Pauli Exclusion Principle?A. 1s22s22p63s23p64s13d7B. 1s22s22p63s23p64s23d5C. 1s22s22p63s23p64s24d6D. 1s22s22p63s23p64s23d6E. 1s22s22p83s23p64s23d3Practice with Electron ConfigurationsCH110 FA11 SAS 17The d-Shell ExceptionsCH110 FA11 SAS 18Half filled and completely filled d-shells are stabilizing and electrons will move to achieve this in the Cr and Cu groupsWhat is the electron configuration of copper in its ground state?Fill in the energy diagram for copper in its ground state:What You Should KnowCH110 FA11 SAS 19Electrons in atoms are quantized• Describe the set of 4 quantum numbers needed to uniquely describe any e-• Quantum numbers describe size, shape, and orientation of orbitals and the spin of the electron. Know which describes each of these.• What is the Pauli Exclusion Principle?Energy Level Diagrams• H atom vs. many-electron atoms; which orbitals are degenerate?• Be able to place the orbitals in order of increasing energy. • Explain why H and many-electron atoms
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