Question

Why is the two O - O bond length in the ozone molecules equal?

Answer 1

In ozone, the three oxygen-atoms are arranged in a bent shape. The central oxygen-atom makes one single bond with one of the terminal oxygen-atom and double bond with the other terminal oxygen-atom. But the pi-electrons of the double bond are delocalised over the three oxygen atoms. Due to which the single and the double bond are not entirely pure but are the hybrids of the single and double bond, giving rise to the oxygen-oxygen bond distance as the average bond distance of the single and double bond.
The resonance structure of the ozone is given below: