State 5 importance of conjugation &
delocalization

In chemistry, a conjugated system is a system of connected p orbitals with delocalized electrons in a molecule, which in general lowers the overall energy of the molecule and increases stability. It is conventionally represented as having alternating single and multiple bonds. Lone pairs, radicals or carbenium ions may be part of the system, which may be cyclic, acyclic, linear or mixed. The term "conjugated" was coined in 1899 by the German chemist Johannes Thiele.[1]

Cinnamaldehyde is a naturally-occurring compound that has a conjugated system

penta-1,3-diene is a molecule with a conjugated system

Diazomethane conjugated pi-system