12 Mg 24.305

Mg - Magnesium

Chemical Element Magnesium Melting Point °C 649
Chemical Symbol Mg Boiling Point °C 1090
Atomic Number 12 Density g/cm3 1.74
Atomic Weight 24.305 Oxide MgO


Magnesium is a silvery-white, lightweight metal, is relatively soft and malleable, and is moderately reactive. Magnesium is the 8th most abundant element on Earth and belongs to Group 2 in the Periodic Table (Alkaline Earth Metals). Magnesium is moderately priced, strong, light and easy to machine; it is protected by a thin layer of oxide on its surface, which is difficult to remove. This layer of oxide means that magnesium does not need to be stored in an oxygen-free environment like the Alkali Metals (Group 1), although it oxidizes with air. Magnesium reacts with water at room temperature, and when it is a powder and is submerged in water, hydrogen bubbles will begin to form on the surface of the metal. Magnesium also reacts with most acids. Magnesium has a reputation for being highly flammable ; whilst this may be true for finely divided magnesium powders and ribbon, bulk magnesium does not burn until it has been heated  to above its melting point (648°C or 1198°F for pure metal). Magnesium has been used for  over 50 years in demanding high temperature applications such as jet engines and nuclear reactors without any practical flammability issues. On burning in air, magnesium produces a brilliant white light, which is an interesting property that gives magnesium some of its uses.  Magnesium is essential for almost all living things.


Magnesium is abundant in the Universe and is formed in supernova stars. Magnesium was first recognised as an element by Joseph Black in 1755.  He showed that magnesium oxide was not the same as calcium oxide, although they were both produced by heating their carbonate ores.  Impure metallic magnesium was first produced in 1792 by Anton Rupprechat, who heated magnesium oxide with charcoal.  A tiny sample of pure metal was first produced by Humphry Davy in 1808 by electrolysis of magnesium oxide.  Magnesium takes its name from Magnesia, a district in Eastern Greece.


The two main magnesium containing minerals are dolomite (CaMg(CO3)2) and magnesite (MgCO3), which are mined to the extent of 10 million tonnes a year in China, Turkey, North Korea, Slovakia, Austria, Russia and Greece.  Reserves of magnesite exceed 2 billion tonnes as ores, and large quantities of magnesium can be found in the oceans.  The majority of magnesium metal is produced by thermal reduction of magnesiumoxide with ferro-silicon, with the remaininga little being produced by electrolysis.


Magnesium oxide is used as a supplement in cattle feed, put into plastics as a bulking agent, producing heat resistant bricks and in products such as lightweight bike frames, car seats and luggage.  It can also be alloyed with up to 10% aluminium and traces of zinc and managese to improve the strength and be used in car bodies and aircrafts.  Magnesium is increasingly being used by car manufacturers due to the environmental benefits, such as having lighter vehicles which last longer.


  • The International Magnesium Association (IMA) 2015
  • Emsley, John. Nature’s Building Blocks, An A-Z Guide to the Elements, New Edition, Oxford University Press, 2011
  • Gray, Theodore. The Elements, A Visual Exploration of Every Known Atom in the Universe, Black Dog & Leventhal Publishers, Inc, NY, 2009
  • Stwertka, Albert. A Guide to the Elements, 3rd Edition, Oxford University Press, 2012

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