Cliffs AP Chemistry, 3rd Edition

3. What is the oxidation number of platinum in PtCl 62 -

A. − 4

B. − 2

C. − 1

D. +4

E. +6

Answer: D

Because chlorine is a halogen, it has an oxidation number of −1. And because there are 6 chlo-
rines, there is a total charge of −6 for the chlorines. The overall charge is −2, so algebraically,
x+ (−6) = −2. Solving this yields x = +4. Thus, the charge (or oxidation number) of platinum
is +4.

4. What type of bond would you expect in CsI?

A. Ionic

B. Covalent

C. Hydrogen

D. Metallic

E. van der Waals

Answer: A

Generally, expect an ionic bond whenever you have a metal (Cs) bonded to a nonmetal (I). If
you have a table of electronegativities to refer to, the electronegativity difference is greater than
1.7 for ionic compounds.

5. Arrange the following ions in order of increasing ionic radius: Mg2+, F–, and O2–.

A. O2–, F–, Mg2+

B. Mg2+, O2–, F–

C. Mg2+, F–, O2–

D. O2–, Mg2+, F–

E. F–, O2–, Mg2+

Ionic Bonding