Magnesium
Symbol: Mg
Atomic Number: 12
Atomic Mass: 24.305 amu (atomic mass units)
Melting Point: 650.0°C (923.15 K, 1202.0°F)
Boiling Point: 1090°C (1363 K, 1994°F)
Number of Protons: 12
Number of Electrons: 12
Number of Neutrons: 12
Classification: Metal
Group Name: Alkaline Earth Metal
Crystal Structure: Hexagonal
Density @ 293 K: 1.738 grams per cubic centimeter
Color: silver/white
The British chemist Sir Humphry Davy isolated pure magnesium metal in 1808. He used electrolysis on a mixture of magnesium oxide (MgO) and mercuric oxide (HgO) to isolate the pure element. The name of the element comes from the Magnesia district in the region of Thessaly, Greece. Davy originally suggested the name “magnium” for the element but then agreed on magnesium.
This light, hard, metal burns at a relatively low temperature to produce a bright, white flame. It is the eighth most abundant element in the universe and the seventh most abundant in the Earth’s crust. Magnesium oxide, also known as magnesia, is the second most abundant compound found in the Earth’s crust.
Magnesium is an essential element for all life. The pigment chlorophyll, which is required for photosynthesis in plants, contains magnesium. It is also essential for the action of many enzymes. The human adult recommended daily amount of magnesium is 0.3 grams per day.
There are three naturally occurring isotopes of magnesium, all of which are stable. In order of abundance, these isotopes are magnesium-24 (78.99%), magnesium-26 (11.01%) and magnesium-25 (10.00%). Unstable isotopes with mass numbers ranging from 20 to 38 are recognized for the element.
Despite being, a very common element magnesium is never found as a free element, as it is so reactive. Magnesium can be extracted from many common minerals including dolomite and carnallite. However, most of the world’s supply of magnesium comes from seawater. One cubic kilometer of seawater will yield approximately 1.3 billion kilograms of magnesium. In non-S.I units, this is 12 billion pounds of magnesium from a cubic mile of seawater. This magnesium has numerous industrial applications as does several of its compounds.
* The bright light produced by burning magnesium finds use in the production photographic flash bulbs, signal flares and fireworks.
* Magnesium alloys have proved very useful. When alloyed to aluminum, it makes the aluminum easier to work. Magnesium-aluminum alloys are very lightweight and are suitable for use in aircraft, rockets and missiles. Other items manufactured from magnesium alloys include snowshoes, horseshoes and baseball catcher’s masks.
* Magnesium oxide (MgO) is used to make crucibles, cements and insulating materials. It is also used to refine some metals from their ores. When added to water it forms magnesium hydroxide (Mg(OH)2) or milk of magnesia. Milk of magnesia is both an antacid and a laxative.
* Hydrated magnesium sulfate (MgSO47H2O) is better known as Epsom Salts. This compound was discovered in a well in Epsom, Surrey, UK in 1618. A farmer finding his cattle would not drink water drawn from the well tasted the water and found it very bitter. He did notice that the water had a healing action on scratches and skin irritation. This water contained magnesium sulfate. Epsom Salts are still used today for treating minor skin abrasions.
* Magnesium carbonate (MgCO3) when added to table salt prevents it caking. It is also of use in the manufacture of paints and inks.
* Magnesium fluoride (MgF2) applied as a thin film to optical lenses reduces glare and reflections.
Reference Sources:
Los Alamos National Laboratory’s Chemistry Division
Jefferson Lab Science Education
Web Elements
