How do halogens such as fluorine and chlorine act as oxidizing agents?

Halogens, such as fluorine and chlorine, act as oxidizing agents by raising the oxidation number of other elements through the transfer of electrons. In this process, the halogen itself is reduced, as its oxidation state changes from 0 to -1.1

This ability to function as an oxidizing agent is rooted in the high electron affinity of halogen atoms, which allows them to readily accept electrons to form stable halide ions. The oxidizing strength of the halogens increases from astatine to fluorine.12

For fluorine, this exceptional reactivity is further enhanced by its relatively low dissociation energy and its ability to form very strong bonds with other elements, resulting in a large heat of reaction. Because fluorine possesses the highest electronegativity of all elements, it is the most powerful oxidizing agent among the halogens.21