Editing Group 9 element (section)

==History==
"Group 9" is the modern standard designation for this group, adopted by the [[IUPAC]] in 1990.<ref name=leigh/> In the [[Group (periodic table)|older group naming systems]], this group was combined with group 8 ([[iron]], [[ruthenium]], [[osmium]], and [[hassium]]) and group 10 ([[nickel]], [[palladium]], [[platinum]], and [[darmstadtium]]) and called group "VIIIB" in the [[Chemical Abstracts Service]] (CAS) "U.S. system", or "VIII" in the old IUPAC (pre-1990) "European system" (and in [[Mendeleev]]'s original table).

===Cobalt===
Cobalt compounds have been used for centuries to impart a rich blue color to [[glass]], [[ceramic glaze|glazes]], and [[Ceramics (art)|ceramics]]. Cobalt has been detected in Egyptian sculpture, Persian jewelry from the third millennium BC, in the ruins of [[Pompeii]], destroyed in 79&nbsp;AD, and in China, dating from the [[Tang dynasty]] (618–907&nbsp;AD) and the [[Ming dynasty]] (1368–1644&nbsp;AD).<ref>[https://www.britannica.com/EBchecked/topic/123235/cobalt-Co Cobalt], Encyclopædia Britannica Online.</ref>

Swedish chemist [[Georg Brandt]] (1694–1768) is credited with discovering cobalt <abbr>c.</abbr> 1735, showing it to be a previously unknown element, distinct from bismuth and other traditional metals. Brandt called it a new "semi-metal".<ref>Georg Brandt first showed cobalt to be a new metal in: G. Brandt (1735) "Dissertatio de semimetallis" (Dissertation on semi-metals), ''Acta Literaria et Scientiarum Sveciae'' (Journal of Swedish literature and sciences), vol. 4, pages 1–10.<br />See also: '''(1)''' G. Brandt (1746) "Rön och anmärkningar angäende en synnerlig färg—cobolt" (Observations and remarks concerning an extraordinary pigment—cobalt), ''Kongliga Svenska vetenskapsakademiens handlingar'' (Transactions of the Royal Swedish Academy of Science), vol. 7, pp. 119–130; '''(2)''' G. Brandt (1748) "Cobalti nova species examinata et descripta" (Cobalt, a new element examined and described), ''Acta Regiae Societatis Scientiarum Upsaliensis'' (Journal of the Royal Scientific Society of Uppsala), 1st series, vol. 3, pp. 33–41; '''(3)''' James L. Marshall and Virginia R. Marshall (Spring 2003) [https://web.archive.org/web/20100703175508/http://www.chem.unt.edu/Rediscovery/Riddarhyttan.pdf "Rediscovery of the Elements: Riddarhyttan, Sweden"]. ''The Hexagon'' (official journal of the [[Alpha Chi Sigma]] fraternity of chemists), vol. 94, no. 1, pages 3–8.</ref><ref name="Wang">{{cite journal|journal =Journal of the Minerals, Metals and Materials Society|volume = 58|issue = 10|date = 2006|doi = 10.1007/s11837-006-0201-y|pages = 47–50|title = Cobalt—Its recovery, recycling, and application|first = Shijie|last = Wang|bibcode = 2006JOM....58j..47W|s2cid = 137613322}}</ref> He showed that compounds of cobalt metal were the source of the blue color in glass, which previously had been attributed to the bismuth found with cobalt. Cobalt became the first metal to be discovered since the pre-historical period. All other known metals (iron, copper, silver, gold, zinc, mercury, tin, lead and bismuth) had no recorded discoverers.

===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>

===Iridium===
Chemists who studied platinum dissolved it in [[aqua regia]] (a mixture of [[hydrochloric acid|hydrochloric]] and [[nitric acid]]s) to create soluble salts. They always observed a small amount of a dark, insoluble residue.<ref name="hunt">{{cite journal |title=A History of Iridium |first=L. B. |last=Hunt |journal=Platinum Metals Review |volume=31 |issue=1 |date=1987 |pages=32–41 |doi=10.1595/003214087X3113241 |url=https://technology.matthey.com/documents/496120/626258/pmr-v31-i1-032-041.pdf/ |access-date=2023-10-12 |archive-date=2022-09-29 |archive-url=https://web.archive.org/web/20220929092320/https://technology.matthey.com/documents/496120/626258/pmr-v31-i1-032-041.pdf/ |url-status=dead |url-access=subscription }}</ref> In 1803, British scientist [[Smithson Tennant]] (1761–1815) analyzed the insoluble residue and concluded that it must contain a new metal. Vauquelin treated the powder alternately with alkali and acids<ref name="Emsley">{{cite book| title=Nature's Building Blocks: An A–Z Guide to the Elements| last=Emsley| first=J.| publisher=[[Oxford University Press]]| date=2003| location=Oxford, England, UK| isbn=978-0-19-850340-8| chapter=Iridium| pages=[https://archive.org/details/naturesbuildingb0000emsl/page/201 201–204]| chapter-url=https://archive.org/details/naturesbuildingb0000emsl/page/201}}</ref> and obtained a volatile new oxide, which he believed to be of this new metal—which he named ''ptene'', from the Greek word {{lang|el|πτηνός}} ''ptēnós'', "winged".<ref>{{cite book |title=A System of Chemistry of Inorganic Bodies |url=https://archive.org/details/asystemchemistr07thomgoog |author=Thomson, T. |author-link=Thomas Thomson (chemist) |publisher=Baldwin & Cradock, London; and William Blackwood, Edinburgh |date=1831 |volume=1 |page=[https://archive.org/details/in.ernet.dli.2015.32266/page/n721/mode/2up 693]}}</ref><ref name="griffith" /> Tennant, who had the advantage of a much greater amount of residue, continued his research and identified the two previously undiscovered elements in the black residue, iridium and osmium.<ref name="hunt" /><ref name="Emsley" /> He obtained dark red crystals (probably of {{chem|Na|2|[IrCl|6}}]·''n''{{chem|H|2|O}}) by a sequence of reactions with [[sodium hydroxide]] and [[hydrochloric acid]].<ref name="griffith" /> He named iridium after [[Iris (mythology)|Iris]] ({{lang|el|Ἶρις}}), the Greek winged goddess of the rainbow and the messenger of the Olympian gods, because many of the [[Salt (chemistry)|salts]] he obtained were strongly colored.{{efn|''Iridium'' literally means "of rainbows".}}<ref>{{cite book |title=Discovery of the Elements |url=https://archive.org/details/discoveryofeleme0000week |url-access=registration |pages=[https://archive.org/details/discoveryofeleme0000week/page/414 414–418] |author=Weeks, M. E. |date=1968 |edition=7th |publisher=Journal of Chemical Education |isbn=978-0-8486-8579-9 |oclc=23991202}}</ref> Discovery of the new elements was documented in a letter to the [[Royal Society]] on June 21, 1804.<ref name="hunt"/><ref>{{cite journal |title=On Two Metals, Found in the Black Powder Remaining after the Solution of Platina |first=S. |last=Tennant |journal=Philosophical Transactions of the Royal Society of London |volume=94 |date=1804 |pages=411–418 |jstor=107152 |doi=10.1098/rstl.1804.0018 |url=https://zenodo.org/record/1432312 |doi-access=}}</ref>

===Meitnerium===
Meitnerium was [[discovery of the chemical elements|first synthesized]] on August 29, 1982, by a German research team led by [[Peter Armbruster]] and [[Gottfried Münzenberg]] at the [[Gesellschaft für Schwerionenforschung|Institute for Heavy Ion Research]] (Gesellschaft für Schwerionenforschung) in [[Darmstadt]].<ref name="82Mu01">{{cite journal|title=Observation of one correlated α-decay in the reaction <sup>58</sup>Fe on <sup>209</sup>Bi→<sup>267</sup>109|doi=10.1007/BF01420157|year=1982|journal=Zeitschrift für Physik A|volume=309|issue=1|pages=89|last1=Münzenberg|first1=G.|last2=Armbruster|first2=P.|last3=Heßberger|first3=F. P.|last4=Hofmann|first4=S.|last5=Poppensieker|first5=K.|last6=Reisdorf|first6=W.|last7=Schneider|first7=J. H. R.|last8=Schneider|first8=W. F. W.|last9=Schmidt|first9=K.-H.|first10=C.-C.|last10=Sahm|first11=D.|last11=Vermeulen|bibcode = 1982ZPhyA.309...89M|s2cid=120062541}}</ref> The team bombarded a target of [[bismuth-209]] with accelerated nuclei of [[iron]]-58 and detected a single atom of the [[isotope]] meitnerium-266:<ref name="93TWG">{{Cite journal|doi=10.1351/pac199365081757|title=Discovery of the transfermium elements. Part II: Introduction to discovery profiles. Part III: Discovery profiles of the transfermium elements|year=1993|author=Barber, R. C.|journal=Pure and Applied Chemistry|volume=65|pages=1757|last2=Greenwood|first2=N. N.|last3=Hrynkiewicz|first3=A. Z.|last4=Jeannin|first4=Y. P.|last5=Lefort|first5=M.|last6=Sakai|first6=M.|last7=Ulehla|first7=I.|last8=Wapstra|first8=A. P.|last9=Wilkinson|first9=D. H.
|issue=8|s2cid=195819585|doi-access=free}} (Note: for Part I see Pure Appl. Chem., Vol. 63, No. 6, pp. 879–886, 1991)</ref>

:{{nuclide|bismuth|209}} + {{nuclide|iron|58}} → {{nuclide|meitnerium|266}} + {{SubatomicParticle|neutron}}

This work was confirmed three years later at the [[Joint Institute for Nuclear Research]] at [[Dubna]] (then in the [[Soviet Union]]).<ref name="93TWG" />