The Periodic Table Chapter 8 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 ns 1 ns 2 ns 2 np 1 ns 2 np 2 ns 2 np 3 ns 2 np 4 ns 2 np 5 ns 2 np 6 d1d1 d5d5 d 10 4f 5f Ground State Electron Configurations of the Elements

3 Classification of the Elements

4 Electron Configurations of Cations and Anions Na [Ne]3s 1 Na + [Ne] Ca [Ar]4s 2 Ca 2+ [Ar] Al [Ne]3s 2 3p 1 Al 3+ [Ne] Atoms lose electrons so that cation has a noble-gas outer electron configuration. H 1s 1 H - 1s 2 or [He] F 1s 2 2s 2 2p 5 F - 1s 2 2s 2 2p 6 or [Ne] O 1s 2 2s 2 2p 4 O 2- 1s 2 2s 2 2p 6 or [Ne] N 1s 2 2s 2 2p 3 N 3- 1s 2 2s 2 2p 6 or [Ne] Atoms gain electrons so that anion has a noble-gas outer electron configuration. Of Representative Elements

Cations and Anions Of Representative Elements

6 Na + : [Ne]Al 3+ : [Ne] F - : 1s 2 2s 2 2p 6 or [Ne] O 2- : 1s 2 2s 2 2p 6 or [Ne]N 3- : 1s 2 2s 2 2p 6 or [Ne] Na +, Al 3+, F -, O 2-, and N 3- are all isoelectronic with Ne What neutral atom is isoelectronic with H - ? H - : 1s 2 same electron configuration as He Isoelectronic: have the same number of electrons, and hence the same ground-state electron configuration

7 Electron Configurations of Cations of Transition Metals When a cation is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the (n – 1)d orbitals. Fe: [Ar]4s 2 3d 6 Fe 2+ : [Ar]4s 0 3d 6 or [Ar]3d 6 Fe 3+ : [Ar]4s 0 3d 5 or [Ar]3d 5 Mn: [Ar]4s 2 3d 5 Mn 2+ : [Ar]4s 0 3d 5 or [Ar]3d 5

8 Effective nuclear charge (Z eff ) is the “positive charge” felt by an electron. Na Mg Al Si Z eff Core Z Radius (pm) Z eff = Z -  0 <  < Z (  = shielding constant) Z eff  Z – number of inner or core electrons

9 Effective Nuclear Charge (Z eff ) increasing Z eff

10 Atomic Radii metallic radius covalent radius

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12 Trends in Atomic Radii

13 Comparison of Atomic Radii with Ionic Radii

14 Cation is always smaller than atom from which it is formed. Anion is always larger than atom from which it is formed.

15 The Radii (in pm) of Ions of Familiar Elements

16 Ionization energy is the minimum energy (kJ/mol) required to remove an electron from a gaseous atom in its ground state. I 1 + X (g) X + (g) + e - I 2 + X + (g) X 2 + (g) + e - I 3 + X 2+ (g) X 3 + (g) + e - I 1 first ionization energy I 2 second ionization energy I 3 third ionization energy I 1 < I 2 < I 3

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18 Filled n=1 shell Filled n=2 shell Filled n=3 shell Filled n=4 shell Filled n=5 shell Variation of the First Ionization Energy with Atomic Number

19 General Trends in First Ionization Energies Increasing First Ionization Energy

20 Electron affinity is the negative of the energy change that occurs when an electron is accepted by an atom in the gaseous state to form an anion. X (g) + e - X - (g) F (g) + e - X - (g) O (g) + e - O - (g)  H = -328 kJ/mol EA = +328 kJ/mol  H = -141 kJ/mol EA = +141 kJ/mol

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22 Diagonal Relationships on the Periodic Table

23 Group 1A Elements (ns 1, n  2) M M e - 2M (s) + 2H 2 O (l) 2MOH (aq) + H 2(g) 4M (s) + O 2(g) 2M 2 O (s) Increasing reactivity

24 Group 2A Elements (ns 2, n  2) M M e - Be (s) + 2H 2 O (l) No Reaction Increasing reactivity Mg (s) + 2H 2 O (g) Mg(OH) 2(aq) + H 2(g) M (s) + 2H 2 O (l) M(OH) 2(aq) + H 2(g) M = Ca, Sr, or Ba

25 Group 2A Elements (ns 2, n  2)

26 Group 3A Elements (ns 2 np 1, n  2) 4Al (s) + 3O 2(g) 2Al 2 O 3(s) 2Al (s) + 6H + (aq) 2Al 3+ (aq) + 3H 2(g)

27 Group 3A Elements (ns 2 np 1, n  2)

28 Group 4A Elements (ns 2 np 2, n  2) Sn (s) + 2H + (aq) Sn 2+ (aq) + H 2 (g) Pb (s) + 2H + (aq) Pb 2+ (aq) + H 2 (g)

29 Group 4A Elements (ns 2 np 2, n  2)

30 Group 5A Elements (ns 2 np 3, n  2) N 2 O 5(s) + H 2 O (l) 2HNO 3(aq) P 4 O 10(s) + 6H 2 O (l) 4H 3 PO 4(aq)

31 Group 5A Elements (ns 2 np 3, n  2)

32 Group 6A Elements (ns 2 np 4, n  2) SO 3(g) + H 2 O (l) H 2 SO 4(aq)

33 Group 6A Elements (ns 2 np 4, n  2)

34 Group 7A Elements (ns 2 np 5, n  2) X + 1e - X - 1 X 2(g) + H 2(g) 2HX (g) Increasing reactivity

35 Group 7A Elements (ns 2 np 5, n  2)

36 Group 8A Elements (ns 2 np 6, n  2) Completely filled ns and np subshells. Highest ionization energy of all elements. No tendency to accept extra electrons.

37 Compounds of the Noble Gases A number of xenon compounds XeF 4, XeO 3, XeO 4, XeOF 4 exist. A few krypton compounds (KrF 2, for example) have been prepared.

38 Properties of Oxides Across a Period basicacidic