Editing Platinum (section)

===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>