A resonance structure is best defined as occurring when . The bond length that occurs in a bond that exhibits resonance will .

A resonance structure is best defined as occurring when multiple valid Lewis structures can be drawn for a molecule or ion that differ only in the placement of electrons, while the positions of the atoms remain constant. This concept illustrates that the actual structure of the molecule is a hybrid or average of all possible resonance forms, which helps in depicting the delocalization of electrons.

The bond length that occurs in a bond that exhibits resonance will be intermediate between that of a single bond and a double bond. This is because the electrons in resonance are delocalized over multiple atoms, resulting in more equal bond character across bonds that would otherwise be of differing lengths. In essence, resonance stabilizes the molecule and leads to bond lengths that are characteristic of both single and double bonds, resulting in shorter bonds than a single bond but longer than a double bond.