A disguised hydride in a butylmagnesium cation.

See more Magnesium products. Magnesium (atomic symbol: Mg, atomic number: 12) is a Block S, Group 2, Period 3 element with an atomic mass of 24.3050. The number of electrons in each of Magnesium's shells is [2, 8, 2] and its electron configuration is [Ne] 3s². The magnesium atom has a radius of 160 pm and a Van der Waals radius of 173 pm. Magnesium was discovered by Joseph Black in 1775 and first isolated by Sir Humphrey Davy in 1808. Magnesium is the eighth most abundant element in the earth's crust and the fourth most common element in the earth as a whole. In its elemental form, magnesium has a shiny grey metallic appearance and is an extremely reactive. It is can be found in minerals such as brucite, carnallite, dolomite, magnesite, olivine and talc. Commercially, magnesium is primarily used in the creation of strong and lightweight aluminum-magnesium alloys, which have numerous advantages in industrial applications. The name "Magnesium" originates from a Greek district in Thessaly called Magnesia.