https://en.m.wikipedia.org/wiki/Polonium
https://en.m.wikipedia.org/wiki/Polonium_dichloride
..
https://en.m.wikipedia.org/wiki/Chlorine_oxide
https://en.m.wikipedia.org/wiki/Dichlorine_monoxide
..
https://en.m.wikipedia.org/wiki/Benzene
https://en.m.wikipedia.org/wiki/Hydrocarbon
..
https://en.m.wikipedia.org/wiki/Resonance_(chemistry)