Why ICI is more reactive than `I_2` ?

Explanation

In interhalogen compounds different halogen atoms are linked by covalent bonds (e.g., ICI, `CIF_3` , `IF_7`). In other words, these are heteroatomic in nature. Due to the difference in the electronegativities of the halogen atom involved, the XX. bond in interhalogens is weaker than X-X bond in halogens except F-F bond. Due to weaker nature of X-X. bond, interhalogen compounds are more reactive than halogens (except `F_2`). For example, ICI is more reactive than `I_2`