Thanks to the alternating single-double nature of the bonds, electrons in these orbitals end up delocalized; the differences between the bonds become a bit irrelevant, and the molecule is best viewed ...

Let us consider formaldehyde. The pictures of the MO's are shown over the skeleton of the molecule, represented as a set of tubes. Below I show the molecular skeleton in two common orientations: from ...

When it comes to extreme multiple bonds, the transition metals have long ruled the roost. Quadruple bonds? They’ve got thousands of them. Quintuple bonds? Right there in a landmark organometallic ...