Page 88 - Theory and Problems of BEGINNING CHEMISTRY

CHAP. 5] CHEMICAL BONDING 77

2
6
6
6
2
2
(d) The configuration of Co 3+ is 1s 2s 2p 3s 3p 3d . An inner electron is removed after both 4s electrons are
removed.
Being able to write correct electronic configurations for transition metal ions becomes very important in
discussions of coordination compounds (in the second semester of general chemistry).

Solved Problems

CHEMICAL FORMULAS
5.1. Which seven elements form diatomic molecules when they are uncombined with other elements?
Ans. H 2 ,N 2 ,O 2 ,F 2 ,Cl 2 ,Br 2 , and I 2 . Remember that the last six of these form a pattern resembling “7” in the
periodic table, starting at element 7.

5.2. How many atoms of each element are there in a formula unit of each of the following substances?

(a)P 4 (c) (NH 4 ) 2 SO 4 (e)I 2 (g)Hg 2 (ClO 3 ) 2
(b)Na 3 PO 4 (d)H 2 O 2 ( f )K 3 PO 4 (h)NH 4 H 2 PO 4
Ans. (a) 4 P atoms (e) 2 I atoms
(b) 3 Na, 1 P, 4 O atoms ( f ) 3 K, 1 P, 4 O atoms
(c) 2 N, 8 H, 1 S, 4 O atoms (g) 2 Hg, 2 Cl, 6 O atoms
(d) 2 H, 2 O atoms (h) 1 N, 6 H, 1 P, 4 O atoms

THE OCTET RULE
5.3. Arrange the electrons in each of the following atoms in shells: (a)F,(b) Cl, (c) Br, and (d)I.
Ans. Shell Number

1 2 3 4 5

(a)F 2 7
(b)Cl 2 8 7
(c) Br 2 8 18 7
(d) I 2 8 18 18 7
5.4. Arrange the electrons in each of the following atoms in shells: (a) Li, (b) Na, (c) K, and (d)Rb.
Ans. Shell Number

1 2 3 4 5

(a)Li 2 1
(b)Na 2 8 1
(c) K 2 8 8 1
(d) Rb 2 8 18 8 1
5.5. Which electron shell is most important to the bonding for each of the following atoms: (a)H,(b) Be,
(c) Al, (d)Sr,(e) Bi, and ( f ) Ra?
Ans. In each case the outermost shell is the most important. (a)1 (b)2 (c)3 (d)5 (e)6 ( f )7