Electron Configuration

1. Electron Configuration Where are the electrons around the nucleus?

2. Order of sublevel energies • S<P<D<F

3. Hund’s Rule • Electrons are added from lowest to highest energy orbitals. • 1 electron is added to each degenerate orbital in a subshell before adding 2 electrons are added to any one orbital

4. Build up (Aufbau)

6. unoccupied orbital orbital with 1 electron orbital with 2 electrons Orbital Diagrams • we often represent an orbital as a square and the electrons in that orbital as arrows • the direction of the arrow represents the spin of the electron Tro, Chemistry: A Molecular Approach

9. Periodic tablePeriods– horizontal rowsGroups—Verticle columns with numbers at the top 1. each period begins with element in 1A column 2. 1A column marks beginning of filling a new principle energy level 3. each consecutive element on the table has one more electron than the last 4. Each element in a group has the identical outer shell configuration except n changes 5. Outer shell (valence shell) configuration accounts for the properties of the elements

12. Z effective Zeff

13. Z effectivehow much the electron “feels” the nucleus Penetration & Shielding Tro, Chemistry: A Molecular Approach

14. Effective Nuclear Charge • in a multi-electron system, electrons are simultaneously attracted to the nucleus and repelled by each other • outer electrons are shieldedfrom full strength of nucleus • screening effect • effective nuclear charge is net positive charge that is attracting a particular electron • Z is nuclear charge, S is electrons in lower energy levels • electrons in same energy level contribute to screening, but very little • effective nuclear charge on sublevels trend,s > p > d > f Zeffective= Z - S Tro, Chemistry: A Molecular Approach

15. Screening & Effective Nuclear Charge

18. Trends in Atomic RadiusTransition Metals • increase in size down the Group • atomic radii of transition metals roughly the same size across the d block • must less difference than across main group elements • valence shell ns2, not the d electrons • effective nuclear charge on the ns2 electrons approximately the same Tro, Chemistry: A Molecular Approach

19. Atomic radius

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21. Which atom of the following pairs has a larger radius? • N or F • C or Ge • N or Al • Al or Ge

22. N or F, N is further left • N or F • C or Ge • N or Al • Al or Ge? opposing trends • N or F • C or Ge, Ge is further down • N or F • C or Ge • N or Al, Al is further down & left Choose the Larger Atom in Each Pair Tro, Chemistry: A Molecular Approach

23. Electron Configuration of Cations in their Ground State • cations form when the atom loses electrons from the valence shell • for transition metals electrons, may be removed from the sublevel closest to the valence shell Al atom = 1s22s22p63s23p1 Al+3 ion = 1s22s22p6 Fe atom = 1s22s22p63s23p64s23d6 Fe+2 ion = 1s22s22p63s23p63d6 Fe+3 ion = 1s22s22p63s23p63d5 Cu atom = 1s22s22p63s23p64s13d10 Cu+1 ion = 1s22s22p63s23p63d10 Tro, Chemistry: A Molecular Approach

24. Trends in Ionic Radius • Ions in same group have same charge • Ion size increases down the group • higher valence shell, larger • Cations smaller than neutral atom; Anions bigger than neutral atom • Cations smaller than anions • except Rb+1 & Cs+1 bigger or same size as F-1 and O-2 • Larger positive charge = smaller cation • for isoelectronic species • isoelectronic = same electron configuration • Larger negative charge = larger anion • for isoelectronic series Tro, Chemistry: A Molecular Approach

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29. Magnetic Properties of Transition Metal Atoms & Ions • electron configurations that result in unpaired electrons mean that the atom or ion will have a net magnetic field – this is called paramagnetism • will be attracted to a magnetic field • electron configurations that result in all paired electrons mean that the atom or ion will have no magnetic field – this is called diamagnetism • slightly repelled by a magnetic field • both Zn atoms and Zn2+ ions are diamagnetic, showing that the two 4s electrons are lost before the 3d • Zn atoms [Ar]4s23d10 • Zn2+ ions [Ar]4s03d10 Tro, Chemistry: A Molecular Approach

30. Write the Electron Configuration and Determine whether the Fe atom and Fe3+ ion are Paramagnetic or Diamagnetic

31. Ionization Energy • minimum energy needed to remove an electron from an atom • gas state • endothermic process • valence electron easiest to remove • M(g) + IE1 M1+(g) + 1 e- • M+1(g) + IE2  M2+(g) + 1 e- • first ionization energy = energy to remove electron from neutral atom; 2nd IE = energy to remove from +1 ion; etc. Tro, Chemistry: A Molecular Approach

32. Ionization energy • Ionization energy: energy required to remove an electron from the atom or ion. • Li Li+ + 1 e- IE = 513.3 kJ/mol (1st ionization energy) Li+  Li2+ + 1e- IE = 7298.0 kJ/mol (2nd ionization energy)

34. Choose the Atom in Each Pair with the Higher First Ionization Energy • Al or S • As or Sb • N or Si • O or Cl

35. Al or S, Al is further left • Al or S • As or Sb, Sb is further down • Al or S • As or Sb • N or Si, Si is further down & left • Al or S • As or Sb • N or Si • O or Cl? opposing trends Choose the Atom in Each Pair with the Higher First Ionization Energy Tro, Chemistry: A Molecular Approach

37. Ionization Energy • 1st ionization energy kJ/mol E + Al  Al+ + e- I=580 E + Al+  Al2+ +e- I = 1815 E + Al2+  Al3+ + e- I=2740 E + Al3+  Al4+ + e- I = 11,600

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40. Metallic Character • Metals • malleable & ductile • shiny, lusterous, reflect light • conduct heat and electricity • most oxides basic and ionic • form cations in solution • lose electrons in reactions - oxidized • Nonmetals • brittle in solid state • dull • electrical and thermal insulators • most oxides are acidic and molecular • form anions and polyatomic anions • gain electrons in reactions - reduced • metallic character increases left • metallic character increase down Tro, Chemistry: A Molecular Approach

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42. Choose the More Metallic Element in Each Pair • Sn or Te • P or Sb • Ge or In • S or Br

43. Sn or Te • P or Sb • Ge or In, In is further down & left • Sn or Te • P or Sb • Ge or In • S or Br? opposing trends • Sn or Te, Sn is further left • Sn or Te • P or Sb, Sb is further down Choose the More Metallic Element in Each Pair Tro, Chemistry: A Molecular Approach