Sodium - Magnesium - Aluminium

Full table
Name, Symbol, NumberMagnesium, Mg, 12
Series Alkaline earth metals
Group, Period, Block2 (IIA), 3, s
Density, Hardness 1738 kg/m3, 2.5
Appearance silvery white
Atomic Properties
Atomic weight 24.305 amu
Atomic radius (calc.) 150 pm (145 pm)
Covalent radius 130 pm
van der Waals radius 173 pm
Electron configuration [Ne]33s2
e- 's per energy level2, 8, 2
Oxidation states (Oxide) 2 (strong base)
Crystal structure Hexagonal
Physical Properties
State of matter solid (paramagnetic)
Melting point 923 K (1202 F)
Boiling point 1363 K (1994 F)
Molar volume 14.00 ×1010-3 m3/mol
Heat of vaporization 127.4 kJ/mol
Heat of fusion 8.954 kJ/mol
Vapor pressure 361 Pa at 923 K
Speed of sound 4602 m/s at 293.15 K
Electronegativity 1.31 (Pauling scale)
Specific heat capacity 1020 J/(kg*K)
Electrical conductivity 22.6 106/m ohm
Thermal conductivity 156 W/(m*K)
1st ionization potential 737.7 kJ/mol
2nd ionization potential 1450.7 kJ/mol
3rd ionization potential 7732.7 kJ/mol
Most Stable Isotopes
isoNAhalf-life DMDE MeVDP
24Mg78.99%Mg is stable with 12 neutrons
25Mg10%Mg is stable with 13 neutrons
26Mg11.01%Mg is stable with 14 neutrons
SI units & STP are used except where noted.
Magnesium is a chemical element in the periodic table that has the symbol Mg and atomic number 12. Magnesium is the eighth most abundant element and constitutes about 2% of the Earth's crust, and it is the third most plentiful element dissolved in seawater. This alkaline earth metal is primarily used as an alloying agent to make aluminium-magnesium alloys.

Table of contents
1 Notable Characteristics
2 Uses
3 History
4 Sources
5 Compounds
6 Isotopes
7 Precautions
8 External Links

Notable Characteristics

Magnesium is a fairly strong, silvery-white, light-weight metal (one third lighter than aluminium) that slightly tarnishes when exposed to air. In a powder, this metal heats and ignites when exposed to air and burns with a white flame. It is difficult to ignite in bulk, though it is easy to light if it is shaved in to thin strips.


Magnesium compounds, primarily
magnesium oxide, are used mainly as refractory material in furnace linings for producing iron and steel, nonferrous metals, glass, and cement. Magnesium oxide and other compounds also are used in agricultural, chemical, and construction industries. This element's principal use is as an alloying additive to aluminium with these aluminium-magnesium alloys being used mainly for beverage cans. Magnesium alloys also are used as structural components of automobiles and machinery. Another use of this metal is to aid the removal of sulfur from iron and steel.

Other uses include:

  • Magnesium, like aluminium, is strong and light, so it is often used in high grade car wheels, called "mag wheels."
  • Combined in alloys this metal is essential for airplane and missile construction.
  • When used as an alloying agent, this metal improves the mechanical, fabrication, and welding characteristics of aluminium.
  • Additive agent for conventional propellants and used in producing nodular graphite in cast iron.
  • Reducing agent for the production of pure uranium and other metals from their salts.
  • Its hydroxide is used in milk of magnesia, its chloride and sulfate in Epsom salts, and its citratess are used in medicine.
  • Dead-burned magnesite is used for refractory purposes such as brick and liners in furnaces and converters.
  • Magnesium is also flammable, burning at a temperature of (4000oF?).
  • The extremely high temperature at which magnesium burns makes it a handy tool for starting emergency fires during outdoor recreation.
  • Magnesium carbonate (MgCO3) powder is also used by athletes, such as gymnasts and weightlifters, to improve the grip on objects -- the apparatus or lifting bar.
  • Other uses include flashlight photography, flares, and pyrotechnics, including incendiary bombs.


The name originates from the
Greek word for a district in Thessaly called Magnesia. Joseph Black in England recognized magnesium as being an element in 1755, Sir Humphrey Davey electrolytically isolated pure magnesium metal in 1808 from a mix of magnesia and HgO and AA Bussy prepared it in coherent form in 1831. Magnesium is the eighth most abundant element in the earth's crust. It is a alkaline earth element and therefore does not occur uncombined with other elements. It is found in large deposits of magnesite, dolomite, and other minerals.


In the
United States this metal is principally obtained by electrolysis of fused magnesium chloride from brines, wells, and sea water. Although magnesium is found in over 60 minerals, only dolomite, magnesite, brucite, carnallite, and olivine are of commercial importance.
Isolation (* follow):
cathode: Mg2+* + 2e- --> Mg
anode: Cl-* Cl2 (gas) + e-


Organic magnesium is important in both
plant and animal life. Chlorophylls are magnesium-centered porphyrins. The adult daily nutritional requirement, which is affected by various factors include weight and size, is about 300 mg/day.


Magnesium-26 is a stable isotope that has found application in
isotopic geology, similar to that of aluminium. Mg-26 is a radiogenic daughter product of Al-26 (half -life = 0.72x106 yr). Large enrichments of stable Mg-26 have been observed in the Ca-Al-rich inclusions of some carbonaceous chondrite meteorites. The anomalous abundance of Mg-26 is attributed to the decay of its parent Al-26 in the inclusions. Therefore, the meteorite must have formed in ation sources and external links: the solar nebula before the Al-26 had decayed. Hence, these fragments are among the oldest objects in the solar system and have preserved information about its earliest history.

It is conventional to plot Mg-26/Mg-24 against an Al/Mg ratio. In an isochron plot, the Al/Mg ratio plotted is Al-27/Mg-24. The slope of the isochron has no age significance, but indicates the initial Al-26/Al-27 ratio in the sample at the time when the systems were separated from a common reservoir.


Magnesium metal is highly flammable in its pure form, especially when it is a powder.
Magnesium metal quickly reacts exothermically upon contact with air or water and should be handeld with care. Water should not be used to extinguish magnesium fires.

External Links