Why is ICl more reactive than I2 ?
(i) In interhalogen compound ICl and I2 the atoms are bonded by covalent bonds.
Reactivity refers to the rate at which a chemical species will undergo reaction in time. For reaction to take place the compound needs to be broken into separate elements first, then the individual elements react with other elements to form new compounds. So any compound which can easily break into their individual elements can react faster.
(ii) The covalent bonds between dissimilar atoms I and Cl atoms in ICl are weaker than between similar atoms in I2. Therefore the bond between ICL will break easily so the I and Cl atom will be easily available to form another compound as compared to the strong bond between I2.
(iii) Therefore bond dissociation enthalpy of all bond is less than that of I2 bond.
Therefore ICl is more reactive than I2.