The halogens can act as oxidising agents by gaining electrons to form halide ions. The oxidising ability decreases down the group with fluorine being the strongest oxidising agent.

Are halogens oxidizing or reducing agents?

Explaining the trend. Down the group, the ease with which these hydrated ions are formed decreases; the halogens become less effective as oxidizing agents, taking electrons from something else less readily.

Why halogens are oxidizing agents?

Thus, halogens need only one more electron to complete their octet and to attain the stable noble gas configuration. ... Therefore, they have a high tendency to gain an electron. Hence, they act as strong oxidizing agents.