1. Periodic Relationships Among the Elements Chapter 7 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 8.1 When the Elements Were Discovered

3. 8.3 Atomic radius – one-half the distance between the two nuclei in two adjacent metal atoms or in a diatomic molecule

4. 8.3

6. General Trend in First Ionization Energies 8.4 Increasing First Ionization Energy

7. Electron affinity is the negative 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) 8.5 F (g) + e - F - (g) O (g) + e - O - (g)  H = -328 kJ/mol EA = +328 kJ/mol  H = -141 kJ/mol EA = +141 kJ/mol

8. Electron affinity – the energy change in kJ accompanying the addition of 1 mol of e- to 1 mol of gaseous atoms or ions.

9. SAMPLE PROBLEMRanking Elements by Atomic Size PLAN: SOLUTION: PROBLEM:Using only the periodic table (not Figure 8.15)m rank each set of main group elements in order of decreasing atomic size: (a) Ca, Mg, Sr(b) K, Ga, Ca(c) Br, Rb, Kr(d) Sr, Ca, Rb Elements in the same group increase in size and you go down; elements decrease in size as you go across a period. (a) Sr > Ca > MgThese elements are in Group 2A(2). (b) K > Ca > GaThese elements are in Period 4. (c) Rb > Br > KrRb has a higher energy level and is far to the left. Br is to the left of Kr. (d) Rb > Sr > CaCa is one energy level smaller than Rb and Sr. Rb is to the left of Sr.

10. SAMPLE PROBLEMRanking Elements by First Ionization Energy PLAN: SOLUTION: PROBLEM:Using the periodic table only, rank the elements in each of the following sets in order of decreasing IE 1 : (a) Kr, He, Ar(b) Sb, Te, Sn(c) K, Ca, Rb(d) I, Xe, Cs IE decreases as you proceed down in a group; IE increases as you go across a period. (a) He > Ar > Kr (b) Te > Sb > Sn (c) Ca > K > Rb (d) Xe > I > Cs Group 8A(18) - IE decreases down a group. Period 5 elements - IE increases across a period. Ca is to the right of K; Rb is below K. I is to the left of Xe; Cs is furtther to the left and down one period.

11. Group 1A Elements (ns 1, n  2) 8.6

12. Group 1A Elements Increasing reactivity 8.6 Low Ionization energies. Tendency to lose the single valance electron They are very reactive, never found in nature in pure state

13. Group 2A Elements (ns 2, n  2) 8.6

14. Group 2A Elements Increasing reactivity 8.6 Alkaline earth metals Metallic character increases from top to bottom

15. Group 3A Elements (ns 2 np 1, n  2) 8.6

16. Group 3A Elements 8.6 Boron is a metalloid; the rest are metals

17. Group 4A Elements (ns 2 np 2, n  2) 8.6

18. Group 4A Elements 8.6 Carbon a non metal Silicon and Germanium are metalloids Then all metals

19. Group 5A Elements 8.6

20. Group 5A Elements 8.6 Nitrogen and Phosphorous are non metals Arsenic and antimony are metalloids Bismuth is a metal

21. Group 6A Elements 8.6

22. Group 6A Elements 8.6 The 1 st three are non metals The last two are metalloids

23. Group 7A Elements 8.6

24. Group 7A Elements Increasing reactivity 8.6 All are halogens and are non metals Great reactivity Never found in their element form in nature High ionization energies Large positive electron affinity

25. Group 8A Elements 8.6 Completely filled ns and np subshells. Highest ionization energy of all elements. No tendency to accept extra electrons.

26. Trends in metallic behavior.