91Ó°ÊÓ

Resonance is a hypothetical process of movement of pi electrons due to the presence of conjugation. conjugation are of many types such as pi and positive charge, pi and Ion pair are on alternative position, pi and free radical are on alternative position, pi and pi electrons are on alternative position, ion pair and positive charge are on alternative position.

Resonating structures are hypothetical structures represent different positions of pi electrons at different time during resonance.

Given compound with a carbocation has conjugation in which double bond are on alternative position and one double bond is on alternative position to charge. Due to conjugation resonance occur and we get resonating structures. In the structure, pi electrons move towards positive charge due to which positive charge displace to that on from which electron are displaced (carbon 3)

In second structure, second double bond electrons move to 3rd carbon and due to this positive charge generated to 5th carbon.

In third stucture, third double bond electrons move to 5th carbon and due to this, positive charge generated to 7th carbon.

Thus, we get three resonating structures and alll are at equilibrium with each other. In one structure positive charge is on 3rd carbon, in seond structure positive charge is on 5th carbon and in third structure positive charge is on 7th carbon.