1. Periodic Properties electron configurations properties hydrogen atom1 electron to remove e - n f = ∞  E = x 6.022 x 10 23 atoms atommol = 1311 kJ mol Z = 1 from ground staten i = 1 2.178 x 10 -18 J  E = 1 nf2nf2 - 1 ni2ni2 - R H Z2Z2 nuclear charge 1s11s1 Ionization Energy, I

2. He + Z = +2  E = 1 nf2nf2 - 1 ni2ni2 - R H Z2Z2 = 5250 kJ/mol 1s11s1  E = 5250 kJ/mol systems with more than 1 electron studied experimentallyionization reactions higher nuclear chargelowers orbital energy - + - 2+ stabilizes system H1s11s1 Z = +1  E = 1311 kJ/mol

3. 1.Effect of 2 electrons in same orbital He 1s21s2 Z = +2  E = 2372 kJ/mol same nuclear charge - 2+ - - orbital energy higher e - e - repulsion less stable easier to remove e - He + 1s11s1  E = 5250 kJ/mol

4. 2.Effect of electrons in different orbital Li Li 2+ 1s21s2 2s12s1 Z = +3  E = 2954 kJ/mol  E = 520 kJ/mol same nuclear charge 3+ ground state2s12s1 excited state 1s1s 1s1s 2s2s2s2s - - - - inner electrons shielding charge Z eff < Z

5. 3.Effect of orbital shape Li 1s21s2 1s21s2 Z = +3  E = 341 kJ/mol  E = 520 kJ/mol same nuclear charge ground state2s12s1 excited state2p12p1 3+ 1s1s 2s2s 1s1s 2p2p - - - - - - s orbitals penetratinglower energy

6. determines orbital energiesPotential Energy 1. Greater nuclear charge (Z) lowers energy 2.Electron-electron repulsionraise energy electrons more difficult to remove electrons easier to remove electrons shield Z inner electrons shield better 3.Orbitals with more penetrationlower energy electrons more difficult to remove s < p < d < f

7. I 1 decreaseZ eff decreasesmore shielding e - I 1 increaseZ increases shielding stays same core e - adding valence e - core e - unchanged

8. 5+ 1s1s 2s2s 2p2p 10+ - 1s1s 2s2s 2p2p - - - - - - - - - BNe - - - - -

9. 4+ 1s1s 2s2s Be B 5+ 1s1s 2s2s 2p2p - - N O - - - - - - - e - e - repulsion

10. Ionization Energy Na I1I1 I2I2 I3I3 I4I4 I5I5 I6I6 I7I7 Mg Al Si P S Cl Ar 495 735 580 780 1060 1005 1255 1527 4560 1445 1815 1575 1890 2260 2295 2665 7730 11,600 16,100 21,200 27,000 very difficult to remove core electrons Second

11. Atomic Radius increase in size n dominates decrease in size Z eff dominates

12. Electron Affinity Energy given off when a gas phase atom gains e - Cl (g) + e -  Cl - (g) Increases Z eff increases Noble gases – no tendency to gain e -

13. Summary atomic radius decreases ionization energy increases electron affinity increases atomic radius increases ionization energy decreases Z eff n metals lose e - non-metals gain e -