Editing Platinum (section)

==Characteristics==

===Physical===
Pure platinum is a lustrous, [[Ductility|ductile]], and [[malleable]], silver-white metal.<ref name="lagowski">{{cite book|title = Chemistry Foundations and Applications|volume = 3|editor = Lagowski, J. J.|pages = [https://archive.org/details/chemistryfoundat0000unse/page/267 267–268]|date = 2004|isbn = 978-0-02-865724-0|publisher = Thomson Gale|url = https://archive.org/details/chemistryfoundat0000unse/page/267}}</ref> Platinum is more ductile than [[gold]], [[silver]] or [[copper]], thus being the most ductile of pure metals, but it is less malleable than gold.<ref>{{cite book |first=M. |last=Schwartz |title=Encyclopedia and Handbook of Materials, Parts and Finishes |publisher=CRC Press |edition=2nd |date=2002 |isbn=9781420017168 |pages= |url=}}</ref><ref>{{cite book |last1=Vaccari |first1=J.A. |last2=Clauser |first2=H.R. |last3=Brady |first3=G.S. |title=Materials handbook: an encyclopedia for managers, technical professionals, purchasing and production managers, technicians, and supervisors |publisher=McGraw-Hill |edition=15th |date=2002 |isbn=9780071360760 |pages= |url=}}</ref>

Its physical characteristics and chemical stability make it useful for industrial applications.<ref>{{cite book|chapter-url = https://books.google.com/books?id=KXwgAZJBWb0C&pg=RA1-PT8|chapter = Platinum|pages = 8–9|isbn = 978-0-87170-518-1|title = Handbook of corrosion data|author1 = Craig, Bruce D|author2 = Anderson, David S|author3 = International, A.S.M.|date = January 1995| publisher=ASM International |url-status = live|archive-url = https://web.archive.org/web/20170324014936/https://books.google.com/books?id=KXwgAZJBWb0C&pg=RA1-PT8|archive-date = 24 March 2017|df = dmy-all}}</ref> Its resistance to wear and tarnish is well suited to use in fine [[Jewellery|jewelry]].

===Chemical===
{{see also|Platinum group}}
[[File:Platin löst sich in heißem Königswasser.jpg|thumb| upright=1.3|left|Platinum being dissolved in hot ''[[aqua regia]]'']]

Platinum has excellent resistance to [[corrosion]]. Bulk platinum does not oxidize in air at any temperature, but it forms a thin surface film of [[Platinum dioxide|{{chem2|PtO2}}]] that can be easily removed by heating to about 400&nbsp;°C.<ref>{{cite web | first=J.C. | last=Chaston | title=Reaction of Oxygen with the Platinum Metals | website=technology.matthey.com | url=https://technology.matthey.com/journal | access-date=2022-07-30 | archive-date=30 July 2022 | archive-url=https://web.archive.org/web/20220730200706/https://technology.matthey.com/journal | url-status=dead }}</ref><ref name="Brewer 1953">{{cite journal |last1=Brewer |first1=Leo |title=Thermodynamic Properties of the Oxides and their Vaporization Processes. |journal=Chemical Reviews |date=1953 |volume=53 |issue= |pages=1–75 |doi=10.1021/cr60161a001 |url=https://pubs.acs.org/doi/pdf/10.1021/cr60161a001|access-date=30 July 2022}}</ref>

The most common [[oxidation state]]s of platinum are +2 and +4. The +1 and +3 oxidation states are less common, and are often stabilized by metal bonding in bimetallic (or polymetallic) species. Tetracoordinate platinum(II) compounds tend to adopt 16-electron [[square planar]] geometries. Although elemental platinum is generally unreactive, it is attacked by [[chlorine]], [[bromine]], [[iodine]], and [[sulfur]]. It reacts vigorously with fluorine at {{convert|500|C}} to form [[platinum tetrafluoride]].<ref name="Lockyer1891">{{cite book|author=Sir Norman Lockyer|title=Nature|url=https://books.google.com/books?id=FswKAAAAYAAJ&pg=PA625|year=1891|publisher=Macmillan Journals Limited|pages=625–|url-status=live|archive-url=https://web.archive.org/web/20170324091844/https://books.google.com/books?id=FswKAAAAYAAJ&pg=PA625|archive-date=24 March 2017|df=dmy-all}}</ref> Platinum is insoluble in [[hydrochloric acid|hydrochloric]] and [[nitric acid]], but dissolves in hot ''[[aqua regia]]'' (a mixture of nitric and hydrochloric acids), to form aqueous [[chloroplatinic acid]], {{chem2|H2PtCl6}}:<ref name="Kauuf" /><ref name="CRC">{{Cite book| author = ((CRC contributors)) | editor = Lide, David R.| chapter = Platinum| date = 2007–2008| title = CRC Handbook of Chemistry and Physics| volume = 4| page= 26| location = New York| publisher = CRC Press| isbn = 978-0-8493-0488-0}}</ref>

: {{chem2|1=Pt + 4 HNO3 + 6 HCl → H2PtCl6 + 4 NO2 + 4 H2O}}

As a [[HSAB theory|soft acid]], the {{chem2|Pt(2+)}} ion has a great affinity for sulfide and sulfur ligands. Numerous DMSO complexes have been reported and care is taken in the choosing of reaction solvents.<ref name="han">{{cite journal|doi = 10.1021/om700543p|title = Mono- vs Bis(carbene) Complexes: A Detailed Study on Platinum(II)−Benzimidazolin-2-ylidenes|date = 2007|first1 = Y. |last1 = Han |first2=H. V. |last2=Huynh |first3=G. K. |last3 = Tan|journal = [[Organometallics]]|volume = 26|pages = 4612–4617|issue = 18}}</ref>

In 2007, the German scientist [[Gerhard Ertl]] won the [[Nobel Prize in Chemistry]] for determining the detailed molecular mechanisms of the catalytic oxidation of [[carbon monoxide]] over platinum ([[catalytic converter]]).<ref>{{cite journal |pages = 385–407|doi = 10.1002/anie.200800480 |title = Reactions at Surfaces: From Atoms to Complexity (Nobel Lecture) |pmid = 18357601 |issue = 19 |date = 2008 |last1 = Ertl |first1 = Gerhard |journal = Angewandte Chemie International Edition |volume = 47 |s2cid = 38416086 }}</ref>

===Isotopes===
{{main|Isotopes of platinum}}
Platinum has six naturally occurring [[isotopes]]: {{chem|190|Pt}}, {{chem|192|Pt}}, {{chem|194|Pt}}, {{chem|195|Pt}}, {{chem|196|Pt}}, and {{chem|198|Pt}}. The most [[isotopic abundance|abundant]] of these is {{chem|195|Pt}}, comprising 33.83% of all platinum. It is the only stable isotope with a non-zero [[Spin (physics)|spin]]. The spin of <sup>1</sup>/<sub>2</sub> and other favourable magnetic properties of the nucleus are utilised in [[Platinum-195 nuclear magnetic resonance|{{chem|195|Pt}} NMR]]. Due to its spin and large abundance, {{chem|195|Pt}} satellite peaks are also often observed in {{chem|1|H}} and {{chem|31|P}} NMR spectroscopy (''e.g.,'' for Pt-phosphine and Pt-alkyl complexes). {{chem|190|Pt}} is the least abundant at only 0.012%. Of the naturally occurring isotopes, only {{chem|190|Pt}} is unstable, though it decays with a half-life of 4.83{{e|11}}&nbsp;years,<ref name="nubase"/> causing an activity of 16.8 [[Becquerel|Bq]]/kg of natural platinum. Other isotopes can undergo [[alpha decay]], but their decay has never been observed, therefore they are considered stable.<ref name="bellidecay">{{cite journal |last1=Belli |first1=P. |last2=Bernabei |first2=R. |last3=Danevich |first3=F. A. |last4=Incicchitti |first4=A. |last5=Tretyak |first5=V. I. |display-authors=3 |title=Experimental searches for rare alpha and beta decays |journal=European Physical Journal A |date=2019 |volume=55 |issue=8 |pages=140–1–140–7 |doi=10.1140/epja/i2019-12823-2 |issn=1434-601X |arxiv=1908.11458|bibcode=2019EPJA...55..140B |s2cid=201664098 }}</ref> Platinum also has 38 synthetic isotopes ranging in atomic mass from 165 to 208, making the total number of known isotopes 44. The least stable of these are {{chem|165|Pt}} and {{chem|166|Pt}}, with half-lives of 260&nbsp;μs, whereas the most stable is {{chem|193|Pt}} with a half-life of 50&nbsp;years. Most platinum isotopes decay by some combination of [[beta decay]] and alpha decay. {{chem|188|Pt}}, {{chem|191|Pt}}, and {{chem|193|Pt}} decay primarily by [[electron capture]]. {{chem|190|Pt}} and {{chem|198|Pt}} are predicted to have energetically favorable [[double beta decay]] paths.<ref name="nubase">{{NUBASE2020}}</ref>

===Occurrence===
[[File:Platinum-nugget.jpg|thumb|left|A native platinum nugget, [[Kondyor Massif|Kondyor]] mine, [[Khabarovsk Krai]]]]
[[File:Platinum-palladium ore, Stillwater mine MT.JPG|thumb|left|Platinum-palladium ore, Stillwater mine, Beartooth Mountains, Montana, US]]
[[File:Sulfidic serpentintite (platinum-palladium ore) Johns-Manville Reef, Stillwater Complex.jpg|thumb|left|Sulfidic serpentinite (platinum-palladium ore) from Stillwater Mine, Beartooth Mountains, Montana, USA]]
Platinum is an extremely rare metal,<ref>{{cite journal |url=https://www.newscientist.com/article/mg19426051-200-earths-natural-wealth-an-audit/ |first=D. |last=Cohen |title=Earth's natural wealth: an audit |journal=New Scientist |date=23 May 2007|volume=194 |issue=2605 |pages=34–41 |doi=10.1016/S0262-4079(07)61315-3 }}</ref> occurring at a concentration of only 0.005 [[Parts per million|ppm]] in [[Earth's crust]].<ref>{{cite book|url=https://books.google.com/books?id=nDhpLa1rl44C&pg=PT141|page=141|title=Encyclopaedia of Occupational Health and Safety: Chemical, industries and occupations|author=Stellman, Jeanne Mager|publisher=International Labour Organization|date=1998|isbn=978-92-2-109816-4|url-status=live|archive-url=https://web.archive.org/web/20170324015653/https://books.google.com/books?id=nDhpLa1rl44C&pg=PT141|archive-date=24 March 2017|df=dmy-all}}</ref><ref>{{cite book|url=https://books.google.com/books?id=5IC6--3zhXMC&pg=PA71|page=71|title=in Symposium on Spectrocemical Analysis for Trace Elements|author=Murata, K. J.|publisher=ASTM International|date=1958|url-status=live|archive-url=https://web.archive.org/web/20170324034432/https://books.google.com/books?id=5IC6--3zhXMC&pg=PA71|archive-date=24 March 2017|df=dmy-all}}</ref>Platinum is often found chemically uncombined as native platinum and as [[alloy]] with the other platinum-group metals mostly. Most often native platinum is found in secondary deposits among [[alluvium|alluvial]] deposits. The alluvial deposits used by [[pre-Columbian]] people in the [[Chocó Department]], [[Colombia]] are still a source for platinum-group metals. Another large alluvial deposit is in the [[Ural Mountains]], Russia, and it is still mined.<ref name="CRC" />

In [[nickel]] and [[copper]] deposits, platinum-group metals occur as [[sulfide]]s (e.g., {{chem2|(Pt,Pd)S)}}, [[telluride (chemistry)|tellurides]] (e.g., {{chem2|PtBiTe}}), [[antimonide]]s (PdSb), and [[arsenide]]s (e.g. {{chem2|PtAs2}}), and as end alloys with nickel or copper. Platinum arsenide, [[sperrylite]] ({{chem2|PtAs2}}), is a major source of platinum associated with nickel ores in the [[Sudbury Basin]] deposit in [[Ontario]], [[Canada]]. At [[Platinum, Alaska]], about {{convert|17000|kg|ozt|abbr=on}} was mined between 1927 and 1975. The mine ceased operations in 1990.<ref>{{cite web
 |url         = http://explorenorth.com/library/communities/alaska/bl-Platinum.htm
 |title       = The History of Platinum
 |access-date  = 12 April 2011
 |website     = Alaska Community Database Online
 |publisher   = ExploreNorth
 |quote       = Platinum is located on the Bering Sea coast, below Red Mountain on the south spit of Goodnews Bay.
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20101222134633/http://explorenorth.com/library/communities/alaska/bl-Platinum.htm
 |archive-date = 22 December 2010
 |df          = dmy-all
}}</ref> The rare [[sulfide mineral]] [[cooperite (mineral)|cooperite]], {{chem2|(Pt,Pd,Ni)S}}, contains platinum along with [[palladium]] and nickel. Cooperite occurs in the [[Merensky Reef]] within the [[Bushveld complex]], [[Gauteng]], [[South Africa]].<ref>{{cite journal|doi = 10.1016/j.mineng.2004.04.001|journal = Minerals Engineering|volume = 17|date = 2004|pages = 961–979|title =Characterizing and recovering the platinum group minerals—a review|first1 = Z.|last1 = Xiao|last2= Laplante |first2=A. R.|issue = 9–10| bibcode=2004MiEng..17..961X }}</ref>

In 1865, [[chromite]]s were identified in the Bushveld region of South Africa, followed by the discovery of platinum in 1906.<ref>Dan Oancea [http://www.infomine.com/publications/docs/Mining.com/Sep2008e.pdf Platinum In South Africa] {{webarchive|url=https://web.archive.org/web/20110813082346/http://www.infomine.com/publications/docs/Mining.com/Sep2008e.pdf |date=13 August 2011 }}. MINING.com. September 2008</ref> In 1924, the geologist [[Hans Merensky]] discovered a large supply of platinum in the [[Bushveld Igneous Complex]] in South Africa. The specific layer he found, named the [[Merensky Reef]], contains around 75% of the world's known platinum.<ref>{{cite journal|url=http://www.technology.matthey.com/article/43/4/146-148/|title=Seventy-fifth Anniversary of the Discovery of the Platiniferous Merensky Reef|journal=Platinum Metals Review|author=R. Grant Cawthorn|year=1999|volume=43 |issue=4 |pages=146–148 |doi=10.1595/003214099X434146148 |access-date=24 Dec 2017|doi-access=free}}</ref><ref name="kirk-pt" /> The large copper–nickel deposits near [[Norilsk#Norilsk-Talnakh nickel deposits|Norilsk]] in [[Russia]], and the [[Sudbury Basin]], [[Canada]], are the two other large deposits. In the Sudbury Basin, the huge quantities of nickel ore processed make up for the fact platinum is present as only 0.5 [[parts per million|ppm]] in the ore. Smaller reserves can be found in the United States,<ref name="kirk-pt">{{cite book |title=Kirk Othmer Encyclopedia of Chemical Technology |first = R. J.|last = Seymour|author2=O'Farrelly, J. I. |chapter=Platinum-group metals |doi=10.1002/0471238961.1612012019052513.a01.pub2 |date=2001 |publisher=Wiley|isbn = 978-0471238966}}</ref> for example in the [[Absaroka Range]] in [[Montana]].<ref name="NewYorkTimes">{{cite news |url=https://query.nytimes.com/gst/fullpage.html?res=9802E3D6153AF930A2575BC0A96E958260 |title=Mining Platinum in Montana |access-date=9 September 2008 |newspaper=New York Times |date=13 August 1998 |url-status=live |archive-url=https://web.archive.org/web/20080203041654/http://query.nytimes.com/gst/fullpage.html?res=9802E3D6153AF930A2575BC0A96E958260 |archive-date=3 February 2008 |df=dmy-all }}</ref> In 2010, South Africa was the top producer of platinum, with an almost 77% share, followed by Russia at 13%; world production in 2010 was {{convert|192,000|kg|abbr=on}}.<ref name="usgs2012-summary">{{cite web |url=http://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2012-plati.pdf |author=Loferski, P. J. |title=Platinum–Group Metals |publisher=USGS Mineral Resources Program |date=July 2012 |access-date=17 July 2012 |url-status=live |archive-url=https://web.archive.org/web/20120707202546/http://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2012-plati.pdf |archive-date=7 July 2012 |df=dmy-all }}</ref>

New approaches to finding platinum deposits by studing ground water found some evidence of new deposits in the state of [[Tamil Nadu]], [[India]].<ref>{{Cite journal |last=Balaram |first=Vysetti |last2=Satyanarayanan |first2=Manavalan |last3=Anabarasu |first3=Kuppan |last4=Rao |first4=Denduluri Venkata Subba |last5=Ali |first5=Mohammed Dar |last6=Kamala |first6=Chigullarevu Tirumala |last7=Charan |first7=Subramaniam Nirmal |date=2019-10-01 |title=Hydrogeochemistry as a Tool for Platinum Group Element (PGE) Exploration – A Case Study from Sittampundi Anorthosite Complex, Southern India |url=https://pubs.geoscienceworld.org/jour-geosocindia/article/94/4/341/633369/Hydrogeochemistry-as-a-Tool-for-Platinum-Group |journal=Journal of the Geological Society of India |language=en |volume=94 |issue=4 |pages=341–350 |doi=10.1007/s12594-019-1321-7 |issn=0974-6889}}</ref>

Platinum exists in higher abundances on the [[Moon]] and in meteorites. Correspondingly, platinum is found in slightly higher abundances at sites of [[bolide]] impact on Earth that are associated with resulting post-impact volcanism, and can be mined economically; the [[Sudbury Basin]] is one such example.<ref>{{cite book|chapter-url = https://books.google.com/books?id=N-CLZhAXQzEC&pg=PA133|chapter = Identification of meteoritic components in imactites|first = Christian|last = Koeberl|isbn = 978-1-86239-017-1|pages = 133–155|title = Meteorites: flux with time and impact effects|date = 1998|url-status = live|archive-url = https://web.archive.org/web/20170324040542/https://books.google.com/books?id=N-CLZhAXQzEC&pg=PA133|archive-date = 24 March 2017|df = dmy-all}}</ref>