How did Linus Pauling use the idea of resonance to describe molecules?

Linus Pauling utilized the theory of resonance to describe molecules by proposing that their true normal state is not represented by a single valence-bond structure, but rather by a resonance hybrid of several distinct, hypothetical structures.1

In his 1931 work, Pauling applied this concept to benzene, suggesting that the molecule exists as a composite state—a weighted average—of five specific configurations: two Kekulé structures and three Dewar structures. By using quantum-mechanical considerations, he demonstrated that the energy of this resonance hybrid is lower than that of any individual alternative structure, a phenomenon known as resonance stabilization.12

Pauling’s approach, detailed in his influential treatise The Nature of the Chemical Bond, emphasized that the molecule is always in this combined state rather than oscillating between different forms. This method allowed chemists to analyze aromatic molecules and other systems where a single, satisfactory structure could not be assigned using traditional bond representations.12