Halogens react with each other to form a number of compounds called interhalogen compounds. Their general formula in ${\mathrm{AX}}_{\mathrm{n}}$; where A is less electronegative halogen while X is a more electronegative halogen and n is its number the interhalogen  compounds are essentially covalent and more reactive than the halogens since the bond $\mathrm{A}-\mathrm{X}$ is weaker than $\mathrm{A}-\mathrm{A}$ or $\mathrm{X}-\mathrm{X}$ bond. The reactions of interhalogens are similar to those of halogens.