resonance (in chemistry)
In chemistry, resonance refers to the theory of molecule structure in which
the actual state of the bonding in a molecule
is expressed as a "resonance hybrid" between two or more valence-bond structures,
and is intermediate between them, but of lower energy. There is no actual
oscillation, and the model is equivalent to molecular orbital
theory. First proposed for benzene, resonance
stabilizes aromatic compounds
and conjugated double-bonded systems such as 1,3-butadiene.
|A carboxylate ion can be thought of as a resonance
hybrid between valence bond structures (A) and (B). Alternatively,
the hybrid structure can be represented as (C).