Question

which of the following has the greatest number of unshared electrons around the central atom?
i3-
sf4
so2
nh3
h2o

Explanation:

• For $\text{I}_3^-$: Central I has 3 lone pairs (6 unshared electrons).
• For $\text{SF}_4$: Central S has 1 lone pair (2 unshared electrons).
• For $\text{SO}_2$: Central S has 1 lone pair (2 unshared electrons).
• For $\text{NH}_3$: Central N has 1 lone pair (2 unshared electrons).
• For $\text{H}_2\text{O}$: Central O has 2 lone pairs (4 unshared electrons).

$\text{I}_3^-$ has the most unshared electrons around the central atom.

Answer:

$\text{I}_3^-$