Question

What is resonance ? And why does it occurs ?

Answer 1

Resonance:

The phenomenon of existence of a molecule in many structures due to delocalization of electrons is called resonance.

These structures are similar in energy, bonding and non-bonding pairs of electrons. Each form of structure is known as canonical form

• Resonance stabilizes the molecule
• Resonance causes equality of bond lengths

OCCURENCE : Electron delocalization lowers the potential energy of the substance and thus makes it more stable than any of the contributing structures. The difference between the potential energy of the actual structure and that of the contributing structure with the lowest potential energy causes resonance effect