Question

the electron - dot structure (lewis structure) for which of the following molecules would have two unshared pairs of electrons on the central atom? a h2s b nh3 c hcn d co2

Explanation:

Step1: Analyze H₂S

Sulfur (S) is the central atom. S has 6 valence - electrons. It forms 2 single bonds with 2 hydrogen atoms, using 2 of its valence - electrons. So, it has 4 remaining electrons which form 2 unshared pairs.

Step2: Analyze NH₃

Nitrogen (N) is the central atom. N has 5 valence - electrons. It forms 3 single bonds with 3 hydrogen atoms, using 3 of its valence - electrons. So, it has 2 remaining electrons which form 1 unshared pair.

Step3: Analyze HCN

Carbon (C) is the central atom. C has 4 valence - electrons. It forms a single bond with H and a triple bond with N, using all 4 of its valence - electrons. So, it has 0 unshared pairs.

Step4: Analyze CO₂

Carbon (C) is the central atom. C has 4 valence - electrons. It forms 2 double bonds with 2 oxygen atoms, using all 4 of its valence - electrons. So, it has 0 unshared pairs.

Answer:

A. H₂S