Page 93 - Theory and Problems of BEGINNING CHEMISTRY

82 CHEMICAL BONDING [CHAP. 5

DISTINCTION BETWEEN IONIC AND COVALENT BONDING
5.39. Describe the bonding of the chlorine atoms in each of the following substances: (a)Cl 2 ,(b) SCl 2 , and
(c) CaCl 2 .
Ans. (a) The chlorine atoms are bonded to each other with a covalent bond. (b) The chlorine atoms are both
bonded to the sulfur atom with covalent bonds. (c) The chlorine atoms are changed to Cl ions, and are
−
bonded to the calcium ion by ionic bonds.
5.40. Draw an electron dot diagram for (a)K 2 SO 4 and (b)H 2 SO 4 . What is the major difference between them?
2−
Ans.
O O
+
(a) 2 K O S O (b) H O S O H
O O

In the potassium salt there is ionic bonding as well as covalent bonding; in the hydrogen compound, there is
only covalent bonding.

5.41. What type of bonding is present in each of the following compounds: (a) AlCl 3 ,(b) NCl 3 , and
(c) Al(ClO) 3 ?
Ans. (a) Ionic (b) Covalent (c) Both ionic and covalent
PREDICTING THE NATURE OF BONDING IN COMPOUNDS
5.42. Which element of each of the following pairs has the higher electronegativity? Consult Table 5-1 only
after writing down your answer. (a) K and Cl, (b) S and O, and (c) Cl and O.
Ans. (a) Cl. It lies farther to the right in the periodic table. (b) O. It lies farther up in the periodic table.
(c) O. It lies farther up in the periodic table, and is more electronegative even though it lies one group to the
left. (See Table 5-1.) O is an exception in this regard.

5.43. Which element is named first in the compound of each of the following pairs: (a) As and O, (b) As and
Br, and (c) S and I?

Ans. (a) As, since it lies to the left of O and below it. (b) As, since it lies left of Br. (c) S, since it lies left of I,
despite the fact that it is above I.

DETAILED ELECTRONIC CONFIGURATIONS OF IONS
5.44. What is the electronic configuration of H ?
+
0
+
Ans. There are no electrons left in H , and so the configuration is ls . This is not really a stable chemical species.
+
+
H is a convenient abbreviation for a more complicated ion, H 3 O .
2−
3+
2−
+
5.45. Write detailed electronic configurations for the following ions: (a)K ,(b)Ti ,(c)S , and (d)Se .
2
6
2
2
2
6
2
2
Ans. (a)K + ls 2s 2p 3s 3p 6 (c) S 2− ls 2s 2p 3s 3p 6
6
2
2
2
2
2
6
10
2
6
6
2
(b)Ti 3+ ls 2s 2p 3s 3p 3d 1 (d)Se 2− ls 2s 2p 3s 3p 4s 3d 4p 6
5.46. What positive ion with a double charge is represented by each of the following configurations:
6
2
2
2
6
2
2
6
2
(a)ls 2s 2p ,(b)ls , and (c)ls 2s 2p 3s 3p ?
Ans. (a)Mg 2+ (b)Be 2+ (c)Ca 2+
5.47. What is the electronic configuration of Pb ?
2+
Ans. The configuration for Pb is
10
14
2
6
2
2
2
6
10
6
2
10
6
2
Pb 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4 f 5d 6p 2