Editing Group 9 element (section)

===Rhodium===
[[File:Wollaston William Hyde Jackson color.jpg|thumb|upright|left|[[William Hyde Wollaston]]]]

Rhodium was discovered in 1803 by [[William Hyde Wollaston]],<ref>{{cite journal |title= On a New Metal, Found in Crude Platina |first=W. H. |last=Wollaston|author-link=William Hyde Wollaston |journal=[[Philosophical Transactions of the Royal Society of London]] |volume=94 |year=1804 |pages=419–430 |doi=10.1098/rstl.1804.0019| url = https://books.google.com/books?id=7AZGAAAAMAAJ&pg=PA419|doi-access=free }}</ref> soon after he discovered [[palladium]].<ref>{{cite journal|journal = Platinum Metals Review|url = http://www.platinummetalsreview.com/dynamic/article/view/47-4-175-183|title = Rhodium and Palladium – Events Surrounding Its Discovery|first = W. P. |last = Griffith|volume = 47|issue = 4|year = 2003|pages = 175–183| doi=10.1595/003214003X474175183 |doi-access = free}}</ref><ref>{{cite journal|title = On the Discovery of Palladium; With Observations on Other Substances Found with Platina|first = W. H.|last = Wollaston|author-link = William Hyde Wollaston|journal = [[Philosophical Transactions of the Royal Society of London]]|volume = 95|year = 1805|pages = 316–330|doi = 10.1098/rstl.1805.0024|doi-access = free}}</ref><ref name="contr">{{cite journal | doi = 10.1080/00033797800200431 | title = The Wollaston/Chenevix controversy over the elemental nature of palladium: A curious episode in the history of chemistry |year = 1978 | last1 = Usselman | first1 = Melvyn | journal = Annals of Science | volume = 35 | issue = 6 | pages = 551–579}}</ref> He used crude [[platinum]] ore presumably obtained from [[South America]].<ref>{{Cite book|author=Lide, David R.|title=CRC handbook of chemistry and physics: a ready-reference book of chemical and physical data|year=2004|publisher=CRC Press|location=Boca Raton|isbn=978-0-8493-0485-9|pages=[https://archive.org/details/crchandbookofche81lide/page/4 4–26]|url-access=registration|url=https://archive.org/details/crchandbookofche81lide/page/4}}</ref> His procedure dissolved the ore in [[aqua regia]] and neutralized the acid with [[sodium hydroxide]] (NaOH). He then precipitated the platinum as [[ammonium chloroplatinate]] by adding [[ammonium chloride]] ({{chem|NH|4|Cl}}). Most other metals like [[copper]], [[lead]], [[palladium]], and rhodium were precipitated with [[zinc]]. Diluted [[nitric acid]] dissolved all but palladium and rhodium. Of these, palladium dissolved in [[aqua regia]] but rhodium did not,<ref>{{Greenwood&Earnshaw2nd|page=1113}}</ref> and the rhodium was precipitated by the addition of [[sodium chloride]] as {{chem| Na|3|[RhCl|6|]·''n''H|2|O}}. After being washed with ethanol, the rose-red precipitate was reacted with zinc, which [[Displacement reaction|displaced]] the rhodium in the ionic compound and thereby released the rhodium as free metal.<ref name="griffith">{{cite journal |title=Bicentenary of Four Platinum Group Metals: Osmium and iridium – events surrounding their discoveries |author=Griffith, W. P. |journal=Platinum Metals Review |volume=47 |issue=4 |year=2003 |pages=175–183|doi=10.1595/003214003X474175183 |doi-access=free }}</ref>