# Where we should put an arrow to represent Coordinate bond in O3?

O=stackrel(ddot)O^(+)-O^(-); from left to right as we face the page, each oxygen atom has $8$, $7$, and $9$ electrons associated with that centre, and hence the formal charge designation, as each oxygen nucleus necessarily has 8 positive nuclear charges. Of course the charges can be distributed over the entire molecule by resonance, but the central oxygen in the molecule is $s {p}_{2} - \text{hybridized}$ to a first approx. with $\angle O - O - O \le {120}^{\circ}$, about ${117}^{\circ}$.