Do you Know !!! What is resonance? Resonance is the way of describing delocalized electrons with in a certain molecule or polyatomic ion Where the bonding can not be expressed by  a single Lewis structure. Molecule / Ion (with delocalized electrons) are represented by several Lewis structures, known as Resonance Structures(Imaginary Structures).Double headed arrow betweenTrick to identify Resonance in a molecule or Ion | How to draw resonance structures – Organic Chemistry