Editing Magnesium (section)

=== Physical properties ===
Elemental magnesium is a gray-white lightweight metal, two-thirds the density of aluminium. Magnesium has the lowest melting ({{convert|923|K|°C}}) and the lowest boiling point ({{convert|1363|K|°C}}) of all the alkaline earth metals.<ref>{{Cite web |title=alkaline-earth metal – Physical and chemical behaviour |url=https://www.britannica.com/science/alkaline-earth-metal/Physical-and-chemical-behaviour |access-date=2022-03-27 |website=Encyclopædia Britannica |language=en}}</ref>

Pure polycrystalline magnesium is brittle and easily fractures along [[shear band]]s. It becomes much more [[ductility|malleable]] when alloyed with small amounts of other metals, such as 1% aluminium.<ref>{{cite journal |doi=10.1038/s41598-017-10384-0 |pmid=28874798 |pmc=5585333 |title=A rare-earth free magnesium alloy with improved intrinsic ductility |journal=Scientific Reports |volume=7 |issue=1 |pages=10458 |year=2017 |last1=Sandlöbes |first1=S. |last2=Friák |first2=M. |last3=Korte-Kerzel |first3=S. |last4=Pei |first4=Z. |last5=Neugebauer |first5=J. |last6=Raabe |first6=D. |bibcode=2017NatSR...710458S}}</ref> The malleability of polycrystalline magnesium can also be significantly improved by reducing its grain size to about 1&nbsp;[[micrometre|μm]] or less.<ref>{{cite journal |doi=10.1038/s41467-017-01330-9 |pmid=29042555 |pmc=5715137 |title=Super-formable pure magnesium at room temperature |journal=Nature Communications |volume=8 |issue=1 |pages=972 |year=2017 |last1=Zeng |first1=Zhuoran |last2=Nie |first2=Jian-Feng |last3=Xu |first3=Shi-Wei |last4=Davies |first4=Chris H. J. |last5=Birbilis |first5=Nick |bibcode=2017NatCo...8..972Z}}</ref>

When finely powdered, magnesium reacts with water to produce hydrogen gas:
: Mg(s) + 2 H<sub>2</sub>O(g) → Mg(OH)<sub>2</sub>(aq) + H<sub>2</sub>(g) + 1203.6&nbsp;kJ/mol
However, this reaction is much less dramatic than the reactions of the alkali metals with water, because the magnesium hydroxide builds up on the surface of the magnesium metal and inhibits further reaction.<ref>{{Cite web |date=2013-10-03 |title=Reactions of Group 2 Elements with Water |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/1Group_2%3A_Chemical_Reactions_of_Alkali_Earth_Metals/Reactions_of_Group_2_Elements_with_Water |access-date=2022-03-27 |website=Chemistry LibreTexts |language=en}}</ref>