Page 91 - Theory and Problems of BEGINNING CHEMISTRY

80 CHEMICAL BONDING [CHAP. 5

ELECTRON DOT NOTATION
5.23. How many electrons are “required” in the valence shell of atoms of each of the following elements in
their compounds: (a)H,(b)O,(c) N, and (d) Ba?
Ans. (a)2 (b)8 (c)8 (d)0

5.24. Draw electron dot diagrams for lithium atoms and sulfur atoms (a) before they react with each other and
(b) after they react with each other.

Ans. Li Li + 2–
(a) S (b) + S
Li Li

3−
2−
5.25. Draw an electron dot diagram for each of the following: (a) Ca, (b) Cl, (c)P,(d)S ,(e)S,( f )P ,
(g) Ne, and (h)Mg .
2+
2– 3– 2+
Ans. . (a) Ca (b) Cl (c) P (d) S (e) S ( f) P ( g) Ne (h) Mg (Both valence
electrons have been lost.)
5.26. Draw an electron dot diagram for Mg 3 N 2 .
2+ 3–
Ans. 3 Mg 2 N

COVALENT BONDING
5.27. Identify the octet of carbon by encircling the electrons that satisfy the octet rule for carbon in
CO 2 . Put rectangles around the electrons that satisfy the octet for the oxygen atoms.
Ans.
O C O

5.28. Draw electron dot diagrams for CH 2 O and C 2 H 4 .
H H H
Ans.
H C O C C
H H

5.29. Explain why hydrogen atoms cannot form double bonds.
Ans. They cannot hold more than two electrons in their valence shell, because it is the first shell. A double bond
includes four electrons.
5.30. Draw electron dot diagrams for oxygen atoms and sulfur atoms (a) before they react with each other and
(b) after they react to form SO 3 .
Ans. (a) O S O (b) O S O
O

O

5.31. The elements hydrogen, nitrogen, and fluorine exist as diatomic molecules when they are not combined
with other elements. Draw an electron dot structure for each molecule.
Ans. HH N N F F