Chemistry - A Molecular Science

Chapter 5 The Covalent Bond

104

H CH H

OC

H

H

H

C C

C

N C

C

H H

H

H

H

OC

H

H C H

H

HP

H

H

a)

b)

c)

d)

39.

Lone pairs are often left out of molecular drawings, but, as we shall see in Chapter 6, they are important in determining the shape of the molecule. Indicate any missing lone pairs in th

e following. (Assume that all atoms

except H obey the octet rule.)

38.

Add double bonds to the Lewis structure of naphthalene (C

H 10

, see top of 8

page for the Lewis structure), the active ingredient in mothballs, so that each carbon atom has an octet. How

many resonance structures can be

drawn for naphthalene? Estimate the le

ngths of the carbon-carbon bonds.

a) Hint: refer to Table 5.3 and the discussion in Section 5.7.

Use the method of Section 4.4 to determine the oxidation state of the carbon.

b)

Use the Lewis structure of the com

pound shown in the margin and the

method presented in Section 5.8 to determine the oxidation state of each carbon atom in C

H 2

O. Does either carbon have the oxidation 4

state derived in part a?

Use the following Lewis struct

ures for Exercises 36-38.

H CH H

H

C

O C

H

H CH

OHC

C C

C C

C

C C

C

H

HH

H

C

Exercise 36

Exercise 37

Exercise 38

H

H

H

H

36.

In compounds with more than one atom of the same type, the oxidation state of those atoms derived from the procedure presented in Section 4.4 leads to the average oxida

tion state of the atom, not the oxidation states of

the individual atoms. For example, consider the molecule C

H 2

O. 4

b) Use the Lewis structure of acetic acid shown to the right and the

method presented in Section 5.8 to determine the oxidation state of each carbon atom in HC

H 2

O 3

. Does either carbon have the oxidation 2

state derived in part a?

a) Use the method of Section 4.4 to determine the oxidation state of the

carbon.

37.

Apply the discussion given in Exercise 36 to acetic acid, HC

H 2

O 3

(See 2

above for the Lewis structure.)

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