Resonance (chemistry)

In molecular chemistry, resonance structures are a conceptual tool used to represent molecules or polyatomic ions where a single Lewis structure is insufficient to describe the bonding accurately. These structures depict different possible arrangements of electrons, particularly delocalized electrons, contributing to a resonance hybrid that more precisely reflects the molecule's true electronic structure.^[1]

Resonance structures are multiple valid Lewis structures for a molecule that cannot be represented adequately by a single structure. They are employed when electrons, especially π-electrons or lone pairs, are delocalized over two or more adjacent atoms. The actual molecule is a resonance hybrid of these structures, exhibiting properties intermediate between the contributing forms. This concept is crucial for understanding the stability, reactivity, and physical properties of various chemical species.