Lewis structure
In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or ions by the combination of several contributing structures (or "forms", also variously known as "resonance structures" or "canonical structures") into a resonance hybrid (or "hybrid structure") in valence bond theory. It has particular value for describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by one single Lewis structure.