Due to low bond dissociation enthalpy, high electronegativity and large electron gain enthalpy, halogens have a strong tendency to accept electrons and thus get reduced.
X + e– → X–
In other words, halogens act as strong oxidising agents, their oxidising power, however, decreases from F2 to I2 as is evident from their electrode potentials :
E° F2/F– = + 2.87 V.E°Cl2/Cl– = + 1.36V
E°Br2/Br– = 1.09V, E°I2/I– = + 0.54V
Oxidizing agent order of halogens:
F2 > Cl2 > Br2 > I2
