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{{redirects|Mg|other uses|MG}}
{{Infobox magnesium}}
[[File:Magnesium.jpg|thumb|Magnesium]]
'''Magnesium''' ( /mæɡˈniːziəm/ mag-NEE-zee-əm) is a [[chemical element]]. It has the symbol ''Mg'', [[atomic number]] 12 and common [[oxidation state]] +2. It is an [[alkaline earth metal]] and the eighth most [[Abundance of chemical elements|abundant]] [[Chemical element|element]] in the [[Earth's crust]]. It makes up 2% of the [[mass]] of the crust. It is the ninth most common element in the [[Observable universe|known]] [[universe]].<ref>{{cite book|last = Ash|first = Russell|title = The Top 10 of Everything 2006: The Ultimate Book of Lists|publisher = Dk Pub|year = 2005|url = http://plymouthlibrary.org/faqelements.htm|isbn = 0756613213|access-date = 2011-09-26|archive-date = 2010-02-10|archive-url = https://web.archive.org/web/20100210170504/http://plymouthlibrary.org/faqelements.htm|url-status = dead}}.</ref> This is because it is easily built up in [[supernova]] stars by addition of three [[helium]] [[nucleus (physics)|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]].<ref>{{cite news|url=http://www.seafriends.org.nz/oceano/seawater.htm#composition|title=The chemical composition of seawater|author=Anthoni, J Floor|year=2006}}</ref>

Magnesium is the 11th most abundant element by mass in the [[human body]]. Its ions are essential to all living [[Cell|cells]]. The ions play a major role in manipulating important biological [[polyphosphate]] compounds like [[Adenosine triphosphate|ATP]], [[DNA]], and [[RNA]]. Hundreds of [[enzyme]]s thus require magnesium ions to function. Magnesium is also the metallic ion at the center of [[chlorophyll]]. It is a common [[additive]] to [[fertilizer]]s.<ref>{{cite web|url=http://www.mg12.info|title=Magnesium in health}}</ref>  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 [[Reactivity (chemistry)|reactive]] (though once produced, it is coated in a thin layer of [[oxide]] (see [[Passivation (chemistry)|passivation]]), which partly masks this reactivity). The free metal burns with a  [[brilliant white]] light, making it a useful ingredient in [[Flare|flares]]. The metal is now mainly obtained by [[electrolysis]] of magnesium salts obtained from [[brine]].
==Uses==
[[Commerce|Commercially]], the main use for the metal is as an alloying agent to make [[aluminium]]-magnesium [[Alloy|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 [[Firework|fireworks]] to make a brilliant bright 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 [[Medicine|medicinally]] as common [[laxative]]s, [[Antacid|antacids]] (i.e. [[milk of magnesia]]), and where [[Stability|stabilization]] of abnormal [[nerve]] excitation and [[blood vessel]] spasm is required (that is, to treat [[eclampsia]]).

Magnesium is used in [[Electronics|electronic]] [[Electronic component|devices]], including: [[mobile phone]]s, [[laptop computer]]s, [[camera]]s, 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 [[alcohol]]s.

Magnesium is also used in [[Incendiary device|incendiary]] bombs, which are bombs that blow up and spread fire everywhere.

== Forms ==

=== Alloys ===
[[File:Cold_rolling_of_Mg_and_Mg-1Al-0.1Ca.jpg|thumb|Magnesium is brittle, and fractures along [[Shear band|shear bands]] when its thickness is reduced by only 10% by [[cold rolling]] (top). However, after alloying Mg with 1% Al and 0.1% Ca, its thickness could be reduced by 54% using the same process (bottom).]]
As of 2013, [[Magnesium alloy|magnesium alloys]] was used less than one million [[Metric ton|tonnes]] per year. This was a lot less than [[Aluminium alloy|aluminium alloys]]. In the same year, 50 million tonnes of [[Aluminium alloy|aluminium alloys]] were used. Using magnesium alloys have limited. This is because magnesium alloys can [[Corrosion|corrode]],<ref name="makar13">{{cite journal|last1=Makar|first1=G. L.|last2=Kruger|first2=J.|year=1993|title=Corrosion of magnesium|journal=International Materials Reviews|volume=38|issue=3|pages=138–153|bibcode=1993IMRv...38..138M|doi=10.1179/imr.1993.38.3.138}}</ref> [[Creep (deformation)|creep]] at high [[Temperature|temperatures]], and [[Combustion|combust]].<ref name="giz">{{cite web|author=Dodson, Brian|date=29 August 2013|title=Stainless magnesium breakthrough bodes well for manufacturing industries|url=http://www.gizmag.com/stainless-magnesium-corrosion-monash/28856|access-date=29 August 2013|publisher=Gizmag.com}}</ref>

=== Compounds ===
Magnesium can makes many different [[Magnesium compounds|compound]]. They are important in [[industry]] and [[biology]]. Some common magnesium compounds are [[magnesium carbonate]], [[magnesium chloride]], [[magnesium citrate]], [[magnesium hydroxide]], [[magnesium oxide]], [[magnesium sulfate]], and magnesium sulfate heptahydrate ([[Epsom salts]]).<ref>{{Cite web|date=2021-03-23|title=8 Types of magnesium and their benefits|url=https://www.medicalnewstoday.com/articles/types-of-magnesium|access-date=2024-05-04|website=www.medicalnewstoday.com|language=en}}</ref><ref>{{Cite web|date=2013-10-02|title=Chemistry of Magnesium (Z=12)|url=https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Supplemental_Modules_and_Websites_(Inorganic_Chemistry)/Descriptive_Chemistry/Elements_Organized_by_Block/1_s-Block_Elements/Group__2_Elements%3A_The_Alkaline_Earth_Metals/Z012_Chemistry_of_Magnesium_(Z12)|access-date=2024-05-04|website=Chemistry LibreTexts|language=en}}</ref>

=== Isotopes ===
Magnesium has three stable [[Isotope|isotopes]]. These isotopes are {{chem|24|Mg}}, {{chem|25|Mg}} and {{chem|26|Mg}}. All of these isotopes are very common in nature. About 79% of Mg is {{chem|24|Mg}}. The isotope {{chem|28|Mg}} is [[Radioactive decay|radioactive]]. In the 1950s to 1970s, many [[Nuclear power plant|nuclear power plants]] made {{chem|28|Mg}} for [[Experiment|experiments]]. This isotope has a fairly short [[Half-life (element)|half-life]] of 21 hours.

== Safety ==
Magnesium burns at a very high temperature, and cannot be put out with water or an ordinary fire extinguisher. It must be extinguished with a class D fire extinguisher. Burning magnesium also produces ultraviolet radiation, which can harm the eyes if it is viewed directly.

==Related pages==
* [[Periodic table]]
* [[List of common elements]]

==References==
<references/>

{{Periodic Table}}{{authority control}}
[[Category:Alkaline earth metals]]