The cleavage of covalent bond $\mathrm{A}-\mathrm{B}\to {\mathrm{A}}^{\bullet }+{\mathrm{B}}^{\bullet }$is known as

Homolytic bond fission: The covalent bond between two atoms gets cleavage and each atom takes a single electron and they form free radicals.

$\mathrm{A}-\mathrm{B}\stackrel{\mathrm{Homolytic} \mathrm{Fission}}{\to }{\mathrm{A}}^{\bullet }+{\mathrm{B}}^{\bullet }$