Editing Gallium (section)

==History==
[[File:Gallium drops.ogv|thumbnail|Small gallium droplets fusing together]]
In 1871, the existence of gallium was first predicted by Russian chemist [[Dmitri Mendeleev]], who named it "[[Mendeleev's predicted elements|eka-aluminium]]" from its position in his [[periodic table]]. He also predicted several properties of eka-aluminium that correspond closely to the real properties of gallium, such as its [[density]], [[melting point]], oxide character, and bonding in chloride.<ref>{{cite book |title=The Ingredients: A Guided Tour of the Elements |author=Ball, Philip |publisher=Oxford University Press |page=105 |date=2002 |isbn=978-0-19-284100-1}}</ref>

:{| class="wikitable"
|+ Comparison between Mendeleev's 1871 predictions and the known properties of gallium<ref name="GreenwoodEarnshaw2nd"/>{{rp|217}}
|-
! Property
! Mendeleev's predictions
! Actual properties
|-
! [[Atomic weight]]
| ~68
| 69.723
|-
! Density
| 5.9&nbsp;g/cm<sup>3</sup>
| 5.904&nbsp;g/cm<sup>3</sup>
|-
! Melting point
| Low
| 29.767&nbsp;°C
|-
! Formula of oxide
| M<sub>2</sub>O<sub>3</sub>
| Ga<sub>2</sub>O<sub>3</sub>
|-
! Density of oxide
| 5.5&nbsp;g/cm<sup>3</sup>
| 5.88&nbsp;g/cm<sup>3</sup>
|-
! Nature of hydroxide
| amphoteric
| amphoteric
|}

Mendeleev further predicted that eka-aluminium would be discovered by means of the [[spectroscope]], and that metallic eka-aluminium would dissolve slowly in both acids and alkalis and would not react with air. He also predicted that M<sub>2</sub>O<sub>3</sub> would dissolve in acids to give MX<sub>3</sub> salts, that eka-[[aluminium salt]]s would form basic salts, that eka-aluminium sulfate should form [[alum]]s, and that anhydrous MCl<sub>3</sub> should have a greater volatility than ZnCl<sub>2</sub>: all of these predictions turned out to be true.<ref name="GreenwoodEarnshaw2nd"/>{{rp|217}}

Gallium was discovered using [[spectroscopy]] by French chemist [[Paul-Émile Lecoq de Boisbaudran]] in 1875 from its characteristic spectrum (two [[violet (color)|violet]] lines) in a sample of [[sphalerite]].<ref name="Bois">{{cite journal |title= Caractères chimiques et spectroscopiques d'un nouveau métal, le gallium, découvert dans une blende de la mine de Pierrefitte, vallée d'Argelès (Pyrénées) |first=Paul Émile  |last= Lecoq de Boisbaudran |pages=493–495 |journal= Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences |volume= 81 |date=1875 }}</ref> <!--{{doi|10.1002/andp.18762351216}}--> Later that year, Lecoq obtained the free metal by [[electrolysis]] of the [[Gallium(III) hydroxide|hydroxide]] in [[potassium hydroxide]] solution.<ref name="Weeks" />

He named the element "gallia", from [[Latin]] {{Lang|la|Gallia}} meaning '[[Gaul]]', a name for his native land of France. It was later claimed that, in a multilingual [[pun]] of a kind favoured by men of science in the 19th century, he had also named gallium after himself: {{Lang|fr|Le coq}} is French for 'the rooster', and the Latin word for 'rooster' is {{Lang|la|gallus}}. In an 1877 article, Lecoq denied this conjecture.<ref name="Weeks">{{cite journal |title= The discovery of the elements. XIII. Some elements predicted by Mendeleeff |pages= 1605–1619 |last= Weeks |first= Mary Elvira |author-link=Mary Elvira Weeks |doi=10.1021/ed009p1605 |journal= [[Journal of Chemical Education]] |volume= 9 |issue= 9 |date= 1932 |bibcode= 1932JChEd...9.1605W}}</ref>

Originally, de Boisbaudran determined the density of gallium as 4.7&nbsp;g/cm<sup>3</sup>, the only property that failed to match Mendeleev's predictions; Mendeleev then wrote to him and suggested that he should remeasure the density, and de Boisbaudran then obtained the correct value of 5.9&nbsp;g/cm<sup>3</sup>, that Mendeleev had predicted exactly.<ref name="GreenwoodEarnshaw2nd"/>{{rp|217}}

From its discovery in 1875 until the era of semiconductors, the primary uses of gallium were high-temperature thermometrics and metal alloys with unusual properties of stability or ease of melting (some such being liquid at room temperature).

The development of [[gallium arsenide]] as a [[direct and indirect band gaps|direct bandgap semiconductor]] in the 1960s ushered in the most important stage in the applications of gallium.<ref name="GreenwoodEarnshaw2nd"/>{{rp|221}} In the late 1960s, the [[electronics industry]] started using gallium on a commercial scale to fabricate light emitting diodes, [[photovoltaics]] and semiconductors, while the metals industry used it<ref name="petkof78">{{cite news |last1=Petkof |first1=Benjamin |title=Gallium |url=https://images.library.wisc.edu/EcoNatRes/EFacs2/MineralsYearBk/MinYB197879v1/reference/econatres.minyb197879v1.bpetkof2.pdf |archive-url=https://web.archive.org/web/20210602213700/https://images.library.wisc.edu/EcoNatRes/EFacs2/MineralsYearBk/MinYB197879v1/reference/econatres.minyb197879v1.bpetkof2.pdf |archive-date=2 June 2021 |url-status=live |agency=USGS Minerals Yearbook |publisher=GPO |date=1978}}</ref> to reduce the melting point of [[alloys]].<ref name="azomga">{{cite news |title=An Overview of Gallium |url=https://www.azom.com/article.aspx?ArticleID=1132 |publisher=AZoNetwork |date=18 December 2001}}</ref>

First blue [[gallium nitride]] LED were developed in 1971-1973, but they were feeble.<ref>{{Cite journal |title=History of Gallium–Nitride-Based Light-Emitting Diodes for Illumination |url=https://ieeexplore.ieee.org/document/6582668 |archive-url=https://web.archive.org/web/20240603083529/https://ieeexplore.ieee.org/document/6582668/ |archive-date=3 June 2024 |access-date=2024-12-20 |journal=Proceedings of the IEEE |date=2013 |doi=10.1109/JPROC.2013.2274929 |language=en-US |url-status=live |last1=Nakamura |first1=Shuji |last2=Krames |first2=M. R. |volume=101 |issue=10 |pages=2211–2220 }}</ref> Only in the early 1990s [[Shuji Nakamura]] managed to combine GaN with [[indium gallium nitride]] and develop the modern blue LED, now making the basis of ubiquitous white LEDs, which [[Nichia]] commercialized in 1993. He and two other Japanese scientists received a [[Nobel Prize in Physics|Nobel in Physics]] in 2014 for this work.<ref>{{Cite web |title=Why It Was Almost Impossible to Make the Blue LED |url=https://www.getrecall.ai/summary/veritasium/why-it-was-almost-impossible-to-make-the-blue-led |access-date=2024-12-20 |website=Recall |language=en}}</ref><ref>{{Cite journal |last=Nakamura |first=Shuji |date=2015 |title=Background story of the invention of efficient blue InGaN light emitting diodes (Nobel Lecture) |url=https://onlinelibrary.wiley.com/doi/full/10.1002/andp.201500801 |journal=Annalen der Physik |volume=527 |issue=5–6 |pages=335–349 |doi=10.1002/andp.201500801 |bibcode=2015AnP...527..335N |issn=1521-3889}}</ref>

Global gallium production slowly grew from several tens of t/year in the 1970s til ca. 2010, when it passed 100 t/yr and rapidly accelerated,<ref>{{Cite journal |last1=Grandell |first1=Leena |last2=Höök |first2=Mikael |date=2015-09-01 |title=Assessing Rare Metal Availability Challenges for Solar Energy Technologies |journal=Sustainability |language=en |volume=7 |issue=9 |pages=11818–11837 |doi=10.3390/su70911818 |issn=2071-1050 |doi-access=free|bibcode=2015Sust....711818G }}</ref> by 2024 reaching about 450 t/yr.<ref>{{Cite journal |date=2024-11-25 |title=Gallium: Assessing the long term future extraction, supply, recycling and price of using WORLD7, in relation to future technology visions in the European Union |url=https://www.researchsquare.com/article/rs-5390312/v1 |access-date=2024-12-20 |website=www.researchsquare.com |doi=10.21203/rs.3.rs-5390312/v1 |language=en |last1=Sverdrup |first1=Harald Ulrik |last2=Haraldsson |first2=Hördur Valdimar }}</ref>