Question

lewis structures practice worksheet – 30 pps
draw the lewis structures for the following compounds:

1. pbr₃

1. n₂h₂

1. ch₃oh

1. no₂⁻¹

1. c₂h₄

Explanation:

Step1: Draw Lewis structure for N₂H₂

N₂H₂: Two N atoms (each 5 valence e⁻) and two H atoms (each 1 valence e⁻). Total valence e⁻: 2×5 + 2×1 = 12. N-N single bond, each N bonded to one H, each N has one lone pair. Structure: H-N=N-H (each N has 2 lone e⁻).

Step2: Draw Lewis structure for CH₃OH

CH₃OH: C (4), 4 H (1 each), O (6). Total valence e⁻: 4 + 4×1 + 6 = 14. C bonded to 3 H and O; O bonded to C and 1 H, with two lone pairs. Structure: H₃C-O-H (O has 2 lone pairs).

Step3: Confirm NO₂⁻ structure (given)

NO₂⁻: N (5) + 2×O (6) + 1 (charge) = 18 valence e⁻. Resonance: N double-bonded to one O, single-bonded to the other (with charge on single-bonded O), each O has lone pairs. Given structure matches resonance form.

Step4: Draw Lewis structure for C₂H₄

C₂H₄: 2×C (4) + 4×H (1) = 12 valence e⁻. C-C double bond, each C bonded to two H. Structure: H₂C=CH₂ (no lone pairs on C).

Answer:

1. PBr₃: As shown (P bonded to 3 Br, each Br has 3 lone pairs, P has 1 lone pair)
2. N₂H₂: H-N=N-H (each N has 2 lone electrons)
3. CH₃OH: H₃C-O-H (O has 2 lone pairs)
4. NO₂⁻: As shown (resonance form with N=O and N-O⁻)
5. C₂H₄: H₂C=CH₂