How many valence electrons do alkali metals have?

Each of the alkali metals has a single valence electron, which contributes to its high level of chemical reactivity. Valence electron shells are defined as the outermost shell of electrons, excluding the ones that comprise a noble gas, because noble gases are generally chemically inert.

The alkali metals make up the first column of the periodic table of elements after hydrogen; they include lithium, sodium, potassium, rubidium, cesium, francium and cerium. The "s" orbital of the last electron shell is most stable; it is occupied by two electrons, which explains the high reactivity of the alkali metals, which have a single electron.