1. A Review of General Chemistry

Use the symbols δ⁺ and δ⁻ to show the direction of the polarity of the indicated bond in each of the following compounds:

g. I—Cl

h. H₂N—OH

Carbon dioxide (CO₂) has no dipole moment (μ = 0 D). The related molecule sulfur dioxide (SO₂) does have a dipole moment (μ = 1.6 D) Explain this observation.

Which bond is stronger? Briefly explain why.

a.

(i) Using the periodic trend, choose the more electronegative atom in each pair. For one pair, you'll need to look at the actual Pauling values. (ii) For which one? (iii) Why?

(b) N vs. O

Show the ionic compound that you would expect to form between the given metal and nonmetal. Label the charges on each species.

(a) Al and F

Use the symbols δ⁺ and δ⁻ to show the direction of the polarity of the indicated bond in each of the following compounds:

e. HO—Br

f. H₃C—Li

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

Which of the following has a bond closest to the ionic end of the bond spectrum?

CH₃NH₂ CH₃CH₃ CH₃F CH₃OH

(a) Rank the following bonds in terms of the strength of their bond dipole (1 = weakest, 6 = strongest).

(b) Which carbon has the largest δ⁺ ?

C―F, C―Br, C―I, C―H, C―C, C―Cl

Given the Lewis structures, indicate the direction of the dipole moment, if there is one.

(b)

Use electronegativities to predict the direction of the dipole moments of the following bonds.

(f) N—Cl

(g) N—O

(h) N—S

(i) N—B

(j) B—Cl

The C≡N triple bond in acetonitrile has a dipole moment of about 3.6 D and a bond length of about 1.16 Å. Calculate the amount of charge separation in this bond. How important is the charge-separated resonance form in the structure of acetonitrile?

For each pair of compounds, predict which one has the higher molecular dipole moment, and explain your reasoning.

a. ethyl chloride or ethyl iodide

b. 1-bromopropane or cyclopropane

Rank the bonds from most polar to least polar.

b. C—Cl, C—I, C—Br

For the molecules shown, indicate the direction of the dipole moment.

(b)