Class 11 NEET Chemistry Classification Of Elements And Periodicity In Properties

In case of diatomic molecules (X2) of halogens the bond dissociation energy decreases in the order : Cl2>Br2>F2>I2
The oxidising power, electronegativity and reactivity decrease in the order : F2>Cl2>Br2>I2
Electron gain enthalpy of halogens follows the given order :
Cl2>F2>Br2>I2
The low value of electron gain enthalpy (electron enthalpy) of fluorine is probably due to small size of fluorine atom.