1. A Review of General Chemistry

Calculate the formal charge of the indicated atom in the following molecules or ions.

(e)

For each of the following compounds and ions,

1. Draw a Lewis structure.

2. Show the kinds of orbitals that overlap to form each bond.

3. Give approximate bond angles around each atom except hydrogen.

d. CH₃–CH=CH₂

e. HC≡C–CHO

f. H₂N–CH₂–CN

Draw the Lewis structure for the following ions. Be sure to calculate the formal charge of each atom to confirm that your structure is correct.

(c) BH₄^-

Which set of formal charges correctly corresponds to the three major resonance forms of $N_{2}O$ (nitrous oxide), written as $N-N-O$?

Calculate the net charge of the molecule

Draw the Lewis structure for the following molecules. Be sure to calculate the formal charge of each atom as a way of confirming your structure is correct.

(b) HOBr

By moving an electron pair, draw a better Lewis structure that minimizes formal charges.

(a)

Given the Lewis structure of ${\mathrm{CO}}_2$, determine the formal charge on each atom.

Draw the Lewis structure for the following ions. Be sure to calculate the formal charge of each atom to confirm that your structure is correct.

(d) AlCl₄^-

Looking ahead in Chapter 3, we describe how the formal charge on an atom can be used to predict the number of lone pairs. Given the charge, or lack of charge, on each atom, fill in the electron pairs.

(c)

An atom with a formal charge does not necessarily have more or less electron density than the atoms in the molecule without formal charges. We can see this by examining the potential maps for H₂O, H₃O⁺, and HO⁻.

<IMAGE>

a. Which atom bears the formal negative charge in the hydroxide ion?

b. Which atom has the greater electron density in the hydroxide ion?

Draw a Lewis structure for each of the following:

b. CO₃²⁻

Draw the missing lone-pair electrons and assign the missing formal charges for the following:

a.

b.

For each of the following structures,

1. Draw a Lewis structure; fill in any nonbonding electrons.

2. Calculate the formal charge on each atom other than hydrogen

d. [(CH₃)₃O]⁺

e. CH₃NC

f. (CH₃)₄NBr

Give each atom the appropriate formal charge:

c.

d.