According to the potential map for the ammonium ion <IMAGE>, which atom has the greatest electron density?

Rank the bonds from most polar to least polar.

d. C—H, C—C, C—N

Rank the bonds from most polar to least polar.

c. H—O, H—N, H—C

Rank the bonds from most polar to least polar.

b. C—Cl, C—I, C—Br

Which of the following molecules would you expect to have a dipole moment of zero?

d. NH₃

e. H₂C═CH₂

f. H₂C═CHBr

Two isomers of 1,2-dichloroethene are known. One has a dipole moment of 2.4 D; the other has zero dipole moment. Draw the two isomers, and explain why one has zero dipole moment.

CHCl=CHCl 1,2-dichloroethene

1. Draw the Lewis structure.

2. Show how the bond dipole moments (and those of any nonbonding pairs of electrons) contribute to the molecular dipole moment.

3. Estimate whether the compound will have a large, small, or zero dipole moment.

g. HCN

h. CH₃CHO

i. H₂C=NH

1. Draw the Lewis structure.

2. Show how the bond dipole moments (and those of any nonbonding pairs of electrons) contribute to the molecular dipole moment.

3. Estimate whether the compound will have a large, small, or zero dipole moment.

d. CH₃F

e. CF₄

f. CH₃OH

Sulfur dioxide has a dipole moment of 1.60 D. Carbon dioxide has a dipole moment of zero, even though C―O bonds are more polar than S―O bonds. Explain this apparent contradiction.