7.23 Why are halogens strong oxidising agents?

The general electronic configuration of halogens is ${\mathrm{ns}}^{2}{\mathrm{np}}^{5}$ , where n = 2-6. Thus, halogens need only one more electron to complete their octet and to attain the stable noble gas configuration. Also, halogens are highly electronegative with low dissociation energies and high negative electron gain enthalpies. Therefore, they have a high tendency to gain an electron. Hence, they act as strong oxidizing agents.