Chemistry is a Science dealing with bond making and bond breaking.
sequence in which bonds are made
as a reactant
is converted into product
is known as the “reaction mechanism”.
In a homolytic cleavage the two electrons of the covalent bond initially connecting two atoms are partitioned so that one electron is associated with each atom. A bond is broken and two radicals are formed (BDE= Bond Dissociation Energy).
In a heterolytic cleavage, the two electrons of the covalent bond initially connecting two atoms move as a pair onto one of the atoms. A bond is broken and two ions are formed. The atom that takes up the two electrons becomes an anion and with no electrons- cation.