Question

1. draw all possible resonance structures for each of these compounds. determine the formal charge on each atom in each of the resonance structures. write the bond order of each bond.

a. so₂
b. no₃⁻

Explanation:

Step1: Resonance structures of SO₂

SO₂ has 2 resonance structures:

1. S double-bonded to left O, single-bonded to right O (lone pairs: S=1, left O=2, right O=3)
2. S double-bonded to right O, single-bonded to left O (lone pairs: S=1, right O=2, left O=3)

Step2: Formal charges for SO₂

Formal charge formula: $FC = V - N - \frac{B}{2}$ (V=valence e⁻, N=lone pair e⁻, B=bonding e⁻)

• Structure 1: S: $6 - 2 - \frac{8}{2}=0$; left O: $6 - 4 - \frac{4}{2}=0$; right O: $6 - 6 - \frac{2}{2}=-1$
• Structure 2: S: $6 - 2 - \frac{8}{2}=0$; right O: $6 - 4 - \frac{4}{2}=0$; left O: $6 - 6 - \frac{2}{2}=-1$

Step3: Bond order of SO₂ bonds

Bond order = total bonds / number of bond positions = 3 / 2 = 1.5

Step4: Resonance structures of NO₃⁻

NO₃⁻ has 3 resonance structures: each O alternates between double and single bonds to N (lone pairs: N=0, double-bonded O=2, single-bonded O=3)

Step5: Formal charges for NO₃⁻

• N: $5 - 0 - \frac{8}{2}=+1$
• Double-bonded O: $6 - 4 - \frac{4}{2}=0$
• Single-bonded O: $6 - 6 - \frac{2}{2}=-1$

Step6: Bond order of NO₃⁻ bonds

Bond order = total bonds / number of bond positions = 4 / 3 ≈ 1.33

Answer:

a. SO₂: 2 resonance structures; formal charges: S=0, one O=0, one O=-1 per structure; bond order=1.5
b. NO₃⁻: 3 resonance structures; formal charges: N=+1, one O=0, two O=-1 per structure; bond order≈1.33