Explain the action of halogen with alkali metals

Explanation

Alkali metals combine readily with halogens to form ionic halides MX Reactivity of alkali metals with halogen increases down the group because of corresponding increase in electropositive character.
`2M+X_(2) to 2M^(+) X^(-)` (M=Li, Na, K, Rb and Cs) (X=F, CI, Brand I)