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No office hours today!

No office hours today!. What’s coming up???. Oct 25 The atmosphere, part 1 Ch. 8 Oct 27 Midterm … No lecture Oct 29 The atmosphere, part 2 Ch. 8 Nov 1 Light, blackbodies, Bohr Ch. 9 Nov 3,5 Postulates of QM, p-in-a-box Ch. 9 Nov 8,10 Hydrogen and multi – e atoms Ch. 9

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No office hours today!

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  1. No office hours today!

  2. What’s coming up??? • Oct 25 The atmosphere, part 1 Ch. 8 • Oct 27 Midterm … No lecture • Oct 29 The atmosphere, part 2 Ch. 8 • Nov 1 Light, blackbodies, Bohr Ch. 9 • Nov 3,5 Postulates of QM, p-in-a-box Ch. 9 • Nov 8,10 Hydrogen and multi – e atoms Ch. 9 • Nov 12, 15 Multi-electron atoms Ch.9,10 • Nov 17 Periodic properties Ch. 10 • Nov 19 Periodic properties Ch. 10 • Nov 22 Valence-bond; Lewis structures Ch. 11 • Nov 24 Hybrid orbitals; VSEPR Ch. 11, 12 • Nov 26 VSEPR Ch. 12 • Nov 29 MO theory Ch. 12 • Dec 1 MO theory Ch. 12 • Dec 2 Review for exam

  3. ORBITAL DIAGRAM Hydrogen has its one electron in the 1s orbital: 1s 2s 2p H: 1s1  Helium has two electrons: both occupy the 1s orbital Pauli principle with opposite spins: 1s 2s 2p He:   1s2 helium ground state Helium can also exist in an excited state such as: 1s 2s 2p He:  1s12s1  Now onto the next atoms

  4. Lithium has three electrons, so it must use the 2s orbital: Beryllium has four electrons, which fill both the 1s and 2s orbitals: Boron’s five electrons fill the 1s and 2s orbitals, and begin to fill the 2p orbitals. Since all three are degenerate, the order in which they are filled does not matter. 1s 2s 2p Li: 1s22s1 1s 2s 2p Be: 1s2 2s2 1s 2s 2p B: 1s22s22p1

  5. CARBON Z=6 A CHOICE 1s 2s 2p C: 1s22s22p2 OR 1s 2s 2p C: 1s22s22p2 How can we decide?????

  6. HUND’S RULE FOR THE GROUND STATE ELECTRONS OCCUPY DEGENERATE ORBITALS SEPARATELY THE SPINS ARE PARALLEL SO FOR CARBON THE GROUND STATE IS 1s 2s 2p C: 1s22s22p2

  7. THE ELECTRON CONFIGURATIONS FOR NITROGEN TO NEON Nitrogen Oxygen Fluorine Neon 1s 2s 2p N: 1s22s22p3 1s 2s 2p O: 1s22s22p4 1s 2s 2p F: 1s22s22p5 1s 2s 2p Ne: 1s22s22p6

  8. H He 1s1 1s2 Li Be B C N O F Ne 2s1 2s2 2p1 2p2 2p3 2p4 2p5 2p6 Na Mg Al Si P S Cl Ar 3s1 3s2 3p1 3p2 3p3 3p4 3p5 3p6 The valence electron configuration of the elements in the periodic table repeat periodically! Every element in a group has the same valence electron configuration!

  9. Sodium has the electron configuration Na: 1s22s22p63s1 And Rb is: 1s22s22p63s23p64s23d104p65s1 abbreviate electron configurations by ... dividing the electrons into…….. valence electrons and core electrons. What does this mean?????

  10. Example Na: 1s22s22p63s1   CORE ELECTRONS VALENCE ELECTRONS are the electrons in the outermost principle quantum level of an atom. highest value of n. Valence electrons are the ones involved in bonding. Noble gases have fully-filled valence shells Example Ar: 1s22s22p63s23p6

  11. ELECTRON CONFIGURATIONS can be abbreviated as a noble gas core and the valence electrons. The configuration for sodium is: Na: 1s22s22p63s1 or Na: [Ne]3s1 Now we can easily write the electron configurations….. QUESTION…..

  12. 4d 5s 4p 3d 4s 3p E 3s 2p 2s 1s POTASSIUM ELECTRONIC CONFIGURATION 1s22s22p62p23s23p64s1 or [Ar]4s1           Q: why does 3d lie above 4s??

  13. SCREENING AND PENETRATION PENETRATION Is to get close to the nucleus SCREENING Is to block the view of other electrons of the nucleus Consider the excited state of helium 1s13p1 LOOK AT RADIAL PROBABILITY DISTRIBUTIONS

  14. SCREENING AND PENETRATION Is 3p THE 1s close to the nucleus PENETRATES WELL SEES A CHARGE OF Z=2 THE 3p DOES NOT SCREEN THE NUCLEUS EFFECTIVE NUCLEAR CHARGE…...

  15. Z eff ´ 2 n SCREENING AND PENETRATION Is 3p THE 1s close to the nucleus Zeff = 2 EFFECTIVE NUCLEAR CHARGE ENERGY MORE NEGATIVE THAN IN H-ATOM E = - 2.178 x 10-19 n

  16. SCREENING AND PENETRATION Is 3p THE 3p far from the nucleus PENETRATES POORLY 1s SCREENS 3p WELL SEES A CHARGE OF Zeff = Z – S = 2-1 = 1

  17. THE 3s orbital penetrates better than 3p orbital The 3p orbital penetrates better than 3d orbital Zeff(s) > Zeff(p) > Zeff(d) 3s 3p 3d

  18. So, in a multi-electron atom Zeff(s) > Zeff(p) > Zeff(d) ENERGY LEVELS REVERSE!! E4s < E3d

  19. H He 1s1 1s2 Li Be B C N O F Ne 2s1 2s2 2p1 2p2 2p3 2p4 2p5 2p6 Na Mg Al Si P S Cl Ar 3s1 3s2 3p1 3p2 3p3 3p4 3p5 3p6 K Ca TRANSITION METALS. The first transition element is scandium, Sc (Z=21) Sc Scandium has the electron configuration: Because….. Sc: [Ar]4s23d1

  20. 4d 5s 4p 3d 4s 3p E 3s 2p 2s 1s ENERGY LEVEL DIAGRAM FOR A MULTI-ELECTRON ATOM SCANDIUM ELECTRONIC CONFIGURATION       Sc: [Ar]4s23d1      Scandium is the first TRANSITION ELEMENT

  21. TRANSITION METALS the metals that fill the d orbitals in their valence shell. WHEN n=3 HUND’S RULE OBEYED FOR ALL EXCEPT Cr and Cu Cr: [Ar] 4s23d4 EXPECTED Cr: [Ar] 4s13d5 …. The d-shell is ½ filled this way; all spin up OBSERVED FOR COPPER

  22. TRANSITION METALS the metals that fill the d orbitals in their valence shell. WHEN n=3 HUND’S RULE OBEYED FOR ALL EXCEPT Cr and Cu Cu: [Ar] 4s23d9 EXPECTED Cu: [Ar] 4s13d10 …. The d-shell is filled this way – extra stable OBSERVED IONS…...

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