Question

What is the molecular shape of a molecule that has three electron pairs in which two pairs are shared and one is an unshared pair?

Answer 1

The electron pairs are trigonal planar to a first approximation.

Explanation:

The electron pairs mutually repel each other; and their most stable geometry is as a trigonal plane, with `120""^@` between the pairs. But we describe molecular geometry on the basis of the disposition, the geometry, of atoms, not electron pairs.

An `AX_2E` molecule would thus be described as bent, with `/_X-A-X` `<` `120^@`. The angle is compressed somewhat in that the lone pair is closer to the central molecule, and repels the bonding pairs of electron. Species of this type include ozone, `O_3`, dichlorocarbene, `"CCl"_2`, and nitrite anion, `NO_2^-`. You should look up the actual bond angles observed for these species.