Question

1. Which one of each of the following pairs will be smaller? Explain your reasoning in each case. (a) Se2- or Br-; (b) O2- or S2-.

2. Compare the charge density values of the three silver ions: Ag+, Ag2+, and Ag3+ (see Appendix 2). Which is most likely to form compounds exhibiting ionic bonding?

3. Using data tables, find the melting points of uranium(III) fluoride, uranium(IV) fluoride, uranium(V) fluoride, and uranium(VI) fluoride. At what point does the bonding type appear to change?

4. Would you expect sodium chloride to dissolve in carbon tetrachloride, CCl4? Explain your reasoning.

5. Which member of the following pairs has the higher melting point? Give your reasoning in each case. (a) copper(I) chloride, CuCl, or copper(II) chloride, CuCl2; (b) lead(II) chloride, PbCl2, or lead(IV) chloride, PbCl4.

6. Rubidium chloride adopts the sodium chloride structure. Calculate the radius of a rubidium ion if the density of rubidium chloride is 2.76 g?cm23 and it is assumed that the ions touch along the edges of the unit cell.

Answer 1

1.(a) Se and Br in the same row of the periodic table 4p⁴ and 4p⁵ the last shell configuration.

Se^2- , its elctronic configuration is

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

and for the Br^- the electronic configuration is the same

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

But the number of protons in Br- is 1 more than Se^2-. Less the number of protons bigger is the size. So, Br - is smaller in size.

1.(b) O and S are in the same group. 2p⁴ and 3p⁴ respectively for the last shell.

O^2- has one less shell than S^2-, so it will be smaller in size.