Editing Magnesium (section)

====Oxidation====
The principal property of magnesium metal is its reducing power. One hint is that it [[tarnish]]es slightly when exposed to air, although, unlike the heavier [[alkaline earth metals]], an oxygen-free environment is unnecessary for storage because magnesium is protected by a thin layer of oxide that is fairly impermeable and difficult to remove.<ref name=":0">{{Cite web |last=MMTA |title=Magnesium |url=https://mmta.co.uk/metals/mg/ |access-date=2023-11-08 |website=MMTA |language=en-US}}</ref>

Direct reaction of magnesium with air or oxygen at ambient pressure forms only the "normal" oxide MgO. However, this oxide may be combined with hydrogen peroxide to form [[magnesium peroxide]], MgO<sub>2</sub>, and at low temperature the peroxide may be further reacted with ozone to form magnesium superoxide Mg(O<sub>2</sub>)<sub>2</sub>.<ref>{{cite journal |last1=Vol'nov |first1=I. I. |last2=Tokareva |first2=S. A. |last3=Belevskii |first3=V. N. |last4=Latysheva |first4=E. I. |title=The formation of magnesium perperoxide Mg(O2)2 in the reaction of magnesium peroxide with ozone |journal=Bulletin of the Academy of Sciences of the USSR Division of Chemical Science |date=March 1970 |volume=19 |issue=3 |pages=468–471 |doi=10.1007/bf00848959 }}</ref>

Magnesium reacts with nitrogen in the solid state if it is powdered and heated to just below the melting point, forming [[Magnesium nitride]] Mg<sub>3</sub>N<sub>2</sub>.<ref>{{Cite journal|last1=Zong|first1=Fujian|last2=Meng|first2=Chunzhan|last3=Guo|first3=Zhiming|last4=Ji|first4=Feng|last5=Xiao|first5=Hongdi|last6=Zhang|first6=Xijian|last7=Ma|first7=Jin|last8=Ma|first8=Honglei|title=Synthesis and characterization of magnesium nitride powder formed by Mg direct reaction with N2|journal=_Journal of Alloys and Compounds|year=2010 |volume=508|issue=1|pages=172–176|doi=10.1016/j.jallcom.2010.07.224}}</ref>

Magnesium reacts with water at room temperature, though it reacts much more slowly than calcium, a similar group 2 metal.<ref name=":0" /> When submerged in water, [[hydrogen]] bubbles form slowly on the surface of the metal; this reaction happens much more rapidly with powdered magnesium.<ref name=":0" /> The reaction also occurs faster with higher temperatures (see {{slink|#Safety precautions}}). Magnesium's reversible reaction with water can be harnessed to store energy and run a [[Magnesium injection cycle|magnesium-based engine]]. Magnesium also reacts exothermically with most acids such as [[hydrochloric acid]] (HCl), producing [[magnesium chloride]] and hydrogen gas, similar to the HCl reaction with aluminium, zinc, and many other metals.<ref>{{Cite web |title=The rate of reaction of magnesium with hydrochloric acid |url=https://edu.rsc.org/experiments/the-rate-of-reaction-of-magnesium-with-hydrochloric-acid/1916.article |access-date=2023-11-08 |website=RSC Education |language=en}}</ref> Although it is difficult to ignite in mass or bulk, magnesium metal will ignite.

Magnesium may also be used as an igniter for [[thermite]], a mixture of aluminium and iron oxide powder that ignites only at a very high temperature.