Question

How do resonance structures affect molecular shape?

Answer 1

Resonance structures don't affect molecular shape, but they explain molecular shape.

For example, the Lewis structure of the carbonate ion CO₃²⁻ is

From this, we predict that it should have two C-O bonds of one length and a C=O bond of a shorter length.

Instead, we find experimentally that all the bonds are the same length.

We explain this by assuming that the CO₃²⁻ ion is a composite or resonance hybrid with three equivalent contributors.

Each C-O bond in the resonance hybrid has exactly the same length.