Group 2 elements are called alkaline earth metals. Magnesium is a grayish-white, fairly tough metal. It tarnishes slightly in air, and finely divided magnesium readily ignites upon heating in air and burns with a dazzling white flame. Normally magnesium is coated with a layer of oxide, MgO, that protects magnesium from air and water. Magnesium is an important element for plant and animal life.
Chlorophylls are porphyrins based upon magnesium.
The adult human daily requirement of magnesium is about 0.3 g day - 1 . Both values are quoted on the Pauling scale. The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. This section gives some data for naturally occurring isotopes.