Because the alkali metals are the group 1 metals, they have only 1 valence electron that they want to lose, and the halogens are the group 17 nonmetals, they want to gain 1 valence electron to become stable.
Because the alkali metals are the group 1 metals, they have only 1 valence electron that they want to lose, and the halogens are the group 17 nonmetals, they want to gain 1 valence electron to become stable.
