Question

What is the formal charge of the central atom in `O_3`?

Answer 1

The central oxygen atom of ozone bears a formal positive charge.

Explanation:

The `O_3` molecule is bent, and displays formal charge separation.

There are `3xx6` valence electrons.

A reasonable Lewis structure would be, `""^(-)O-stackrel(+)O=O`, and going from the left oxygen to right, around each oxygen centre there are `7`, `5`, and `6` electrons respectively. And thus the central oxygen bears a positive charge, and the left most oxygen bears a negative charge. With this formulation, the ozone molecule is still formally neutral. The terminal oxygens are equivalent by resonance.