Bond order

The Coulson pi bond order from Huckel molecular orbitals, and Pauling’s bond-order/bond-length correlation.

Coulson’s molecular-orbital bond order in butadiene, hexatriene, and benzene

Coulson's molecular-orbital bond order in butadiene, hexatriene, and benzene

Pauling’s bond-order and bond-length correlation for carbon-carbon bonds

Pauling's bond-order and bond-length correlation for carbon-carbon bonds