What is the difference between alkali and alkaline earth metals?

One column on the periodic table. The alkali metals are in group IA, and are much more reactive than the alkaline earth metals, which are in group IIA. The alkali metals have only one valence electron in the outermost s-orbital, while the alkaline earth metals have two electrons in the outermost s-orbital. The alkali metals have lower ionization energies than do the alkaline earth metal, and the same is true for electronegativities.