Ch13 Even Solns

Ch13 Even Solns - CHAPTER THIRTEEN BONDING: GENERAL...

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CHAPTER THIRTEEN BONDING: GENERAL CONCEPTS Chemical Bonds and Electronegativity 12. a. There are two attractions of the form (+1)(-1)/r , where r = 1 × 10 -10 m = 0.1 nm. V = 2 × (2.31 × 10 -19 J nm) = -4.62 × 10 -18 J b. There are 4 attractions of +1 and -1 charges at a distance of 0.1 nm from each other. The two negative charges and the two positive charges repel each other across the diagonal of the square. This is at a distance of √2 × 0.1 nm. V = -9.24 × 10 -18 J + 1.63 × 10 -18 J + 1.63 × 10 -18 J = -5.98 × 10 -18 J Note: There is a greater net attraction in arrangement b than in a. 14. The most polar bond will have the greatest difference in electronegativity between the two atoms. From positions in the periodic table, we would predict: a. Ge-F b. P-Cl c. S-F d. Ti-Cl e. Sn-H f. Tl-Br 16. (IE – EA) ( IE – EA)/ 502 EN (text) 2006/502 = 4.0 F 2006 kJ/mol 4.0 4.0 Cl 1604 3.2 3.2 Br 1463 2.9 3.0 I 1302 2.6 2.7 The values calculated from IE and EA show the same trend (and agree fairly closely) to the values given in the text.
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Ionic Compounds 18. a. Mg 2+ : 1s 2 2s 2 2p 6 Sn 2+ : [Kr]5s 2 4d 10 K + : 1s 2 2s 2 2p 6 3s 2 3p 6 Al 3+ : 1s 2 2s 2 2p 6 Tl + : [Xe]6s 2 4f 14 5d 10 As 3+ : [Ar]4s 2 3d 10 b. N 3— , O 2— and F : 1s 2 2s 2 2p 6 Te 2— :[Kr]5s 2 4d 10 5p 6 c. Be 2+ : 1s 2 Rb + : [Ar]4s 2 3d 10 4p 6 Ba 2+ : [Kr]5s 2 4d 10 5p 6 Se 2— : [Ar]4s 2 3d 10 4p 6 I : [Kr]5s 2 4d 10 5p 6 20. a. Sc 3+ b. Te 2— - c. Ce 4+ and Ti 4+ d. Ba 2+ 0 All of these have the number of electrons of a noble gas. 22. Lattice energy is proportional to Q 1 Q 2 /r where Q is the charge of the ions and r is the distance between the ions. In general, charge effects on lattice energy are greater than size effects. a. LiF; Li + is smaller than Cs + . b. NaBr; Br is smaller than I . c. BaO; O 2— has a greater charge than Cl . d. CaSO 4 ; Ca 2+ has a greater charge than Na + . e. K 2 O; O 2— - has a greater charge than F . f. Li 2 O; The ions are smaller in Li 2 O. 24. Ionic solids can be characterized as being held together by strong omnidirectional forces. i. For electrical conductivity, charged species must be free to move. In ionic solids the charged ions are held rigidly in place. Once the forces are disrupted (melting or dissolution), the ions can move about (conduct). ii. Melting and boiling disrupts the attractions of the ions for each other. If the forces are strong, it will take a lot of energy (high temp.) to accomplish this. iii. If we try to bend a piece of material, the atoms/ions must slide across each other. For an ionic solid the following might happen:
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Just as the layers begin to slide, there will be very strong repulsions causing the solid to snap across a fairly clean plane. These properties and their correlation to chemical forces will be discussed in detail in
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This note was uploaded on 04/07/2008 for the course CHEM 027 taught by Professor Mccallum during the Spring '08 term at Pacific.

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Ch13 Even Solns - CHAPTER THIRTEEN BONDING: GENERAL...

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