Editing Selenium (section)

==History==
[[File:Luna statue.jpg|thumb|upright|Selenium is named after the [[Selene]], the Greek Goddess of the [[Moon]]]]
Selenium ([[Greek language|Greek]] σελήνη ''[[selene]]'' meaning "Moon") was discovered in 1817 by [[Jöns Jacob Berzelius]] and [[Johan Gottlieb Gahn]].<ref>{{cite journal |last1=Berzelius |first1=J.J.|title=Lettre de M. Berzelius à M. Berthollet sur deux métaux nouveaux |journal=Annales de Chimie et de Physique |year=1818 |volume=7 |pages=199–206 |url=https://books.google.com/books?id=jBIAAAAAMAAJ&pg=PA199 |series=2nd series |trans-title=Letter from Mr. Berzelius to Mr. Berthollet on two new metals |language=fr}} From p. 203: ''"Cependant, pour rappeler les rapports de cette dernière avec le tellure, je l'ai nommée sélénium."'' (However, in order to recall the relationships of this latter [substance (viz, selenium)] to tellurium, I have named it "selenium".)</ref> Both chemists owned a chemistry plant near [[Gripsholm]], Sweden, producing [[sulfuric acid]] by the [[lead chamber process]]. [[Pyrite]] samples from the [[Falun Mine]] produced a red solid precipitate in the lead chambers, which was presumed to be an arsenic compound, so the use of pyrite to make acid was discontinued. Berzelius and Gahn, who wanted to use the pyrite, observed that the red precipitate gave off an odor like [[horseradish]] when burned. This smell was not typical of arsenic, but a similar odor was known from [[tellurium]] compounds. Hence, Berzelius's first letter to [[Alexander Marcet]] stated that this was a tellurium compound. However, the lack of tellurium compounds in the [[Falun Mine]] minerals eventually led Berzelius to reanalyze the red precipitate, and in 1818 he wrote a second letter to Marcet describing a newly found element similar to [[sulfur]] and tellurium. Because of its similarity to tellurium, named for the Earth, Berzelius named the new element after the [[Moon]].<ref>{{cite journal |doi=10.1021/ed009p474 |title=The Discovery of the Elements. VI. Tellurium and Selenium |date=1932 |last1=Weeks |first1=Mary Elvira |author-link1=Mary Elvira Weeks |journal=Journal of Chemical Education |volume=9 |issue=3 |page=474 |bibcode=1932JChEd...9..474W}}</ref><ref>{{cite journal |title=Berzelius' Discovery of Selenium |first=Jan |last=Trofast |url=http://www.iupac.org/publications/ci/2011/3305/5_trofast.html |journal=Chemistry International |volume=33 |issue=5 |year=2011 |pages=16–19}} [http://www.iupac.org/publications/ci/2011/3305/sept11.pdf#page=18 PDF]</ref>

In 1873, [[Willoughby Smith]] found that the [[electrical conductivity]] of grey selenium was affected by light.<ref>{{cite journal |last1=Smith |first1=Willoughby |title=The action of light on selenium |journal=Journal of the Society of Telegraph Engineers |year=1873 |volume=2 |issue=4 |pages=31–33 |url=https://babel.hathitrust.org/cgi/pt?id=uiug.30112007449892;view=1up;seq=67 |doi=10.1049/jste-1.1873.0023}}</ref><ref>{{cite journal |last1=Smith |first1=Willoughby |title=Effect of light on selenium during the passage of an electric current |journal=Nature |date=20 February 1873 |volume=7 |issue=173 |page=303 |url=https://babel.hathitrust.org/cgi/pt?id=uc1.c2754884;view=1up;seq=321 |doi=10.1038/007303e0 |bibcode=1873Natur...7R.303.|doi-access=free }}</ref> This led to its use as a cell for sensing light. The first commercial products using selenium were developed by [[Werner Siemens]] in the mid-1870s. The selenium cell was used in the [[photophone]] developed by [[Alexander Graham Bell]] in 1879. Selenium transmits an electric current proportional to the amount of light falling on its surface. This phenomenon was used in the design of [[light meter]]s and similar devices. Selenium's semiconductor properties found numerous other applications in electronics.<ref>{{cite journal |url=https://books.google.com/books?id=diwDAAAAMBAJ&pg=PA116 |title=Action of light on selenium|journal =[[Popular Science]] |year=1876 |volume=10 |issue=1 |page=116 |author1=Bonnier Corporation}}</ref><ref>{{cite book |url= https://books.google.com/books?id=CaxdTFMwQEAC&pg=PA77 |title= Earliest semiconductor device| pages= 77–79 |series= Getting to Know Semiconductors |isbn=978-981-02-3516-1|last1= Levinshtein |first1=M.E. |last2=Simin |first2=G.S. |date=1992-12-01 |df=dmy-all}}</ref><ref>{{cite book |url=https://books.google.com/books?id=IYsOEa_AIjUC&pg=PA89 |page=89 |title= Media Technology and Society: A History: From the Telegraph to the Internet |isbn= 978-0-415-14229-8 |last1=Winston |first1=Brian |date=1998-05-29 |publisher=Psychology Press |df=dmy-all}}</ref> The development of [[selenium rectifier]]s began during the early 1930s, and these replaced [[copper oxide]] rectifiers because they were more efficient.<ref>{{cite book |url=https://books.google.com/books?id=rslXJmYPjGIC&pg=PA18 |page=18 |title=A History of the World Semiconductor Industry |isbn=978-0-86341-227-1 |last1=Morris |first1=Peter Robin |date=1990}}</ref><ref>{{cite journal |last=Bergmann |first=Ludwig |year=1931 |journal=Physikalische Zeitschrift |volume=32 |pages=286–288 |title=Über eine neue Selen-Sperrschicht-Photozelle}}</ref><ref>{{cite journal |doi=10.1021/ie50392a002 |title=Industrial Utilization of Selenium and Tellurium |year=1942 |last1=Waitkins |first1=G.R. |last2=Bearse |first2=A.E. |last3=Shutt |first3=R. |journal=Industrial & Engineering Chemistry |volume=34 |issue=8 |pages=899–910}}</ref> These lasted in commercial applications until the 1970s, following which they were replaced with less expensive and even more efficient [[silicon rectifier]]s.

Selenium came to medical notice later because of its toxicity to industrial workers. Selenium was also recognized as an important veterinary toxin, which is seen in animals that have eaten high-selenium plants. In 1954, the first hints of specific biological functions of selenium were discovered in [[microorganism]]s by biochemist, [[Jane Gibson|Jane Pinsent]].<ref>{{cite journal |pmc=1269698 |title=The need for selenite and molybdate in the formation of formic dehydrogenase by members of the Coli-aerogenes group of bacteria |volume=57 |issue =1 |journal=Biochem. J. |year=1954 |pages=10–16 |author=Pinsent, Jane |pmid=13159942 |doi=10.1042/bj0570010}}</ref><ref>{{cite book |doi=10.1007/0-306-47466-2_267 |volume=10 |year=2002 |last1=Stadtman |first1=Thressa C. |isbn=978-0-306-46378-5 |title=Trace Elements in Man and Animals 10 |pages=831–836 |chapter=Some Functions of the Essential Trace Element, Selenium}}</ref> It was discovered to be essential for mammalian life in 1957.<ref>{{cite journal |doi=10.1021/ja01569a087 |year=1957 |last1=Schwarz |first1=Klaus |last2=Foltz |first2=Calvin M. |journal=Journal of the American Chemical Society |volume=79 |issue=12 |pages=3292–3293 |title=Selenium as an Integral Part of Factor&nbsp;3 Against Dietary Necrotic Liver Degeneration|bibcode=1957JAChS..79.3292S }}</ref><ref>{{cite book |doi=10.1007/0-387-33827-6_1 |year=2006 |last1=Oldfield |first1=James E. |isbn=978-0-387-33826-2 |title=Selenium |pages=1–6 |chapter=Selenium: A historical perspective}}</ref> In the 1970s, it was shown to be present in two independent sets of [[enzyme]]s. This was followed by the discovery of [[selenocysteine]] in proteins. During the 1980s, selenocysteine was shown to be encoded by the [[Genetic code|codon UGA]]. The recoding mechanism was worked out first in [[bacteria]] and then in [[mammal]]s (see [[SECIS element]]).<ref>{{cite journal |doi=10.1128/MCB.22.11.3565-3576.2002 |title=How Selenium Has Altered Our Understanding of the Genetic Code |year=2002 |last1=Hatfield |first1=D. L. |last2=Gladyshev |first2=V.N. |journal=Molecular and Cellular Biology |volume=22 |issue=11 |pages=3565–3576 |pmid=11997494 |pmc=133838}}</ref>