Magnesium

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sodiummagnesiumaluminium
Be

Mg

Ca
Appearance
shiny grey solid


Spectral lines of Magnesium
General properties
Name, symbol, number magnesium, Mg, 12
Pronunciation /mæɡˈnziəm/
mag-NEE-zee-əm
Element category alkaline earth metal
Group, period, block 23, s
Standard atomic weight 24.3050(6)g·mol−1
Electron configuration [Ne] 3s2
Electrons per shell 2, 8, 2 (Image)
Physical properties
Phase solid
Density (near r.t.) 1.738 g·cm−3
Liquid density at m.p. 1.584 g·cm−3
Melting point 923 K, 650 °C, 1202 °F
Boiling point 1363 K, 1091 °C, 1994 °F
Heat of fusion 8.48 kJ·mol−1
Heat of vaporization 128 kJ·mol−1
Specific heat capacity (25 °C) 24.869 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 701 773 861 971 1132 1361
Atomic properties
Oxidation states 2, 1[1]
(strongly basic oxide)
Electronegativity 1.31 (Pauling scale)
Ionization energies
1st: 737.7 kJ·mol−1
2nd: 1450.7 kJ·mol−1
3rd: 7732.7 kJ·mol−1
Atomic radius 160 pm
Covalent radius 141±7 pm
Van der Waals radius 173 pm
Miscellanea
Crystal structure hexagonal close packed
Magnetic ordering paramagnetic
Electrical resistivity (20 °C) 43.9 nΩ·m
Thermal conductivity (300 K) 156 W·m−1·K−1
Thermal expansion (25 °C) 24.8 µm·m−1·K−1
Speed of sound (thin rod) (r.t.) (annealed)
4940 m·s−1
Young's modulus 45 GPa
Shear modulus 17 GPa
Bulk modulus 45 GPa
Poisson ratio 0.290
Mohs hardness 2.5
Brinell hardness 260 MPa
CAS registry number 7439-95-4
Most stable isotopes
Main article: Isotopes of magnesium
iso NA half-life DM DE (MeV) DP
24Mg 78.99% 24Mg is stable with 12 neutrons
25Mg 10.00% 25Mg is stable with 13 neutrons
26Mg 11.01% 26Mg is stable with 14 neutrons
Magnesium

Magnesium ( /mæɡˈniːziəm/ mag-NEE-zee-əm) is a chemical element with the symbol Mg, atomic number 12 and common oxidation state +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust, where it constitutes about 2% by mass, and ninth in the known universe as a whole.[2] This preponderance of magnesium is related to the fact that it is easily built up in supernova stars from a sequential addition of three helium nuclei to carbon (which in turn is made from three helium nuclei). Magnesium ion's high solubility in water helps ensure that it is the third most abundant element dissolved in seawater.[3]

Magnesium is the 11th most abundant element by mass in the human body. Its ions are essential to all living cells. The ions play a major role in manipulating important biological polyphosphate compounds like ATP, DNA, and RNA. Hundreds of enzymes thus require magnesium ions to function. Magnesium is also the metallic ion at the center of chlorophyll, and is thus a common additive to fertilizers.[4] Magnesium ions are sour to the taste, and in low concentrations help to impart a natural tartness to fresh mineral waters.

The free element (metal) is not found naturally on Earth, as it is highly reactive (though once produced, is coated in a thin layer of oxide (see passivation), which partly masks this reactivity). The free metal burns with a characteristic brilliant white light, making it a useful ingredient in flares. The metal is now mainly obtained by electrolysis of magnesium salts obtained from brine.

Uses[change | change source]

Commercially, the chief use for the metal is as an alloying agent to make aluminium-magnesium alloys, sometimes called "magnalium" or "magnelium". Since magnesium is less dense than aluminium, these alloys are prized for their relative lightness and strength.

Magnesium is used in fireworks to make a brilliant white light.Another use is to mix it with other metals to make it strong, lightweight alloys such as those used to make bicycle frames.

Magnesium compounds are used medicinally as common laxatives, antacids (i.e., milk of magnesia), and in a number of situations where stabilization of abnormal nerve excitation and blood vessel spasm is required (that is, to treat eclampsia).

Magnesium is used in electronic devices, including: mobile phones, laptop computers, cameras, and other electronic components. Magnesium's low weight, good mechanical and electrical properties are good for these uses.

Magnesium reacted with an alkyl halide gives a Gringard reagent, which is a very useful tool for preparing alcohols.

Magnesium is also used in incendiary bombs, which are bombs that blow up and spread fire everywhere.

Other pages[change | change source]

References[change | change source]

  1. Bernath, P. F., Black, J. H., & Brault, J. W. (1985). "The spectrum of magnesium hydride". Astrophysical Journal 298: 375. doi:10.1086/163620 . http://bernath.uwaterloo.ca/media/24.pdf.
  2. Ash, Russell (2005). The Top 10 of Everything 2006: The Ultimate Book of Lists. Dk Pub. ISBN 0756613213 . http://plymouthlibrary.org/faqelements.htm..
  3. Anthoni, J Floor (2006). "The chemical composition of seawater". http://www.seafriends.org.nz/oceano/seawater.htm#composition.
  4. "Magnesium in health". http://www.mg12.info.