Oxygen (O2) wants two more electrons, so normally shares them with a partner using two covalent bonds: O=O

I'd always assumed ozone (O3) formed a single bond with each neighbour in a loop. Two bonds each, simple.

But no! There's no loop, and it switches between O-O=O and O=O-O like a maniac, with essentially 1.5 bonds each!? What!?

https://en.m.wikipedia.org/wiki/Ozone #chemistry