When a chemical reaction initiates, all the bonds of reactants get broken and new bonds are formed during and after the reaction. This process of breaking down the bond during chemical reaction is called cleavage of bonds. There are two types of cleavage in general.
1. Homolytic cleavage: It involves the fission of covalent bond in such a way that each of the bonded atom takes away one electron out of their shared pair. It is shown by half headed curved arrows. This type of fission generally occurs if the bonded atoms have similar electronegativities. It is generally form in the presence of light, heat, peroxide etc.
Homolytic cleavage produces:
- Free radical species.
- Paramagnetic species.
2. Heterolytic cleavage: In heterolytic cleavage, the shared pair is taken by one of the most electronegative atoms. It is shown by bend arrow. This type of fission generally occurs if the bonded atoms have different electronegativities.
Heterolytic fission produces:
- Ionic species called carbocation or carboanion.
- Diamagnetic species.