Question

Why are halogens strong oxidising agents?

Answer 1

Hint: All elements in the halogen family have 7 electrons in their valence shell. So for these elements, gaining an electron is always a preferred way to complete octet and become stable i.e. achieve nearest noble gas electronic configuration.

Complete step-by-step answer:
Fluorine, Chlorine, Bromine, Iodine and Astatine are the 5 elements present in group 17 and are called as Halogens. In Greek, the word Halogens means salt producer. Their general electronic configuration is ${\text{n}}{{\text{s}}^{\text{2}}}{\text{ n}}{{\text{p}}^{\text{5}}}$.i.e. they have 7 electrons in their valence shell and hence need just 1 electron in their outer shell to achieve nearest noble gas configuration and become stable. This increases their ability to gain electrons and hence they have high value of electronegativity.
Oxidation is basically loss of electrons and the species which loses an electron is said to be oxidised. Consequently, the species which gains this electron is said to be reduced itself but is an oxidising agent. Hence, halogens are strong oxidising agents.

Additional information: Fluorine and Chlorine exist as gases; Bromine is a liquid whereas Iodine and Astatine are mostly solids at room temperature. This makes group 17 the only group or family in the periodic table which contains elements in all states of matter at room temperature.

Note: Halogens lie on the extreme right side of the periodic table i.e. to the immediate left of noble gases and are known to have very high values of electronegativity. We know that electronegativity decreases down the group but these elements still have the highest values of electronegativity as compared to other elements in their respective periods.