The alkali earth metals are also called s- block elements because these elelements have one electron each in the valence s- subshell of their atoms i.e, they have ns1 configuration. The Alkali metals include lithium, sodium, potassium, rubidium, cesium, and francium.They are called alkali metals since they readily dissolves in water to form soluble hydroxides, which are strongly alkaline in nature. Because they have only one electron in valence subshell,therefore, they lose easily, owing to their low ionization energies. Therefore, alkali metals are highly reactive chemically & donot exist in free or native state & are not easily found in nature.
