The alkaline earth metals are a group of elements on the periodic table. They are all metals. They are similar to the alkali metals. They are a little harder (can only be cut by a knife with difficulty), heavier, and less reactive. Beryllium and magnesium only react with water very slowly. Calcium reacts with water quite rapidly, but slower than lithium or sodium. The other metals react rapidly. Barium and beryllium are toxic, while calcium and magnesium are vital minerals. They are reducing agents.