Editing Astatine (section)

== History ==
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  | base_alt = Periodic table by Mendeleev (1871), with astatine missing below chlorine, bromine and iodine ("J")
  | base_caption = Mendeleev's table of 1871, with an empty space at the eka-iodine position
  | base_link = Periodic_table#History
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|caption={{longitem|[[Dmitri Mendeleev]]'s table of 1871, with an empty space at the eka-iodine position}}
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In 1869, when [[Dmitri Mendeleev]] published his [[Periodic table#Mendeleev|periodic table]], the space under iodine was empty; after [[Niels Bohr]] established the physical basis of the classification of chemical elements, it was suggested that the fifth halogen belonged there. Before its officially recognized discovery, it was called "eka-iodine" (from [[Sanskrit]] {{tlit|sa|eka}} 'one') to imply it was one space under iodine (in the same manner as [[Mendeleev's predicted elements|eka-silicon, eka-boron, and others]]).<ref>{{cite book|last=Ball|first=P.|title=The Ingredients: A Guided Tour of the Elements|publisher=Oxford University Press|year=2002|pages=100–102 | isbn = 978-0-19-284100-1 }}</ref> Scientists tried to find it in nature; given its extreme rarity, these attempts resulted in several false discoveries.{{sfn|Lavrukhina|Pozdnyakov|1970|pp=227–228}}

The first claimed discovery of eka-iodine was made by [[Fred Allison]] and his associates at the Alabama Polytechnic Institute (now [[Auburn University]]) in 1931. The discoverers named element 85 "alabamine", and assigned it the symbol Ab, designations that were used for a few years.<ref>{{cite journal | title = Evidence of the Detection of Element 85 in Certain Substances| first1 = F. | last1 =Allison | author-link1=Fred Allison| first2 = E. J. | last2 =Murphy| first3 = E. R. | last3 =Bishop| first4 = A. L. | last4 =Sommer | journal = Physical Review | volume = 37 | pages = 1178–1180 | year = 1931 | doi = 10.1103/PhysRev.37.1178 | issue = 9|bibcode = 1931PhRv...37.1178A }} {{subscription required}}</ref><ref>{{cite magazine | url = http://www.time.com/time/magazine/article/0,9171,743159,00.html | archive-url = https://web.archive.org/web/20070930015028/http://www.time.com/time/magazine/article/0,9171,743159,00.html | url-status = dead | archive-date = 30 September 2007 | title = Alabamine & Virginium |magazine=[[Time (magazine)|Time]] | date=15 February 1932}}</ref><ref>{{cite journal | title = What Happened to Alabamine, Virginium, and Illinium? | last= Trimble | first = R. F. | journal = Journal of Chemical Education | volume = 52 | page = 585 | year = 1975 | doi =10.1021/ed052p585 | issue = 9|bibcode = 1975JChEd..52..585T }} {{subscription required}}</ref> In 1934, [[Herbert G. MacPherson|H. G. MacPherson]] of [[University of California, Berkeley]] disproved Allison's method and the validity of his discovery.<ref>{{cite journal| last = MacPherson| first = H. G.| title = An Investigation of the Magneto-optic Method of Chemical Analysis| journal = Physical Review| volume = 47| issue = 4| pages = 310–315|year=1934|doi = 10.1103/PhysRev.47.310|bibcode = 1935PhRv...47..310M }}</ref> There was another claim in 1937, by the chemist Rajendralal De. Working in Dacca in [[British India]] (now [[Dhaka]] in [[Bangladesh]]), he chose the name "dakin" for element 85, which he claimed to have isolated as the [[thorium series]] equivalent of [[Radium#History|radium F]] (polonium-210) in the [[radium series]].<ref name="Mellor" /> The properties he reported for dakin do not correspond to those of astatine,<ref name="Mellor" /> and astatine's radioactivity would have prevented him from handling it in the quantities he claimed.<ref name="findingekaiodine" /> Moreover, astatine is not found in the thorium series, and the true identity of dakin is not known.<ref name=Mellor>{{cite book | first=J. W. | last=Mellor | author-link=Joseph William Mellor | title=A Comprehensive Treatise on Inorganic and Theoretical Chemistry | publisher=Longmans, Green | year=1965 | oclc=13842122 | page=[https://archive.org/details/comprehensivetre00mellrich/page/n1081 1066] | url = https://archive.org/details/comprehensivetre00mellrich }}</ref>

In 1936, the team of Romanian physicist [[Horia Hulubei]] and French physicist [[Yvette Cauchois]] claimed to have discovered element 85 by observing its X-ray emission lines. In 1939, they published another paper which supported and extended previous data. In 1944, Hulubei published a summary of data he had obtained up to that time, claiming it was supported by the work of other researchers. He chose the name "dor", presumably from the Romanian for "longing" [for peace], as [[World War II]] had started five years earlier. As Hulubei was writing in French, a language which does not accommodate the "-ine" suffix, dor would likely have been rendered in English as "dorine", had it been adopted. In 1947, Hulubei's claim was effectively rejected by the Austrian chemist [[Friedrich Paneth]], who would later chair the [[IUPAC]] committee responsible for recognition of new elements. Even though Hulubei's samples did contain astatine-218, his means to detect it were too weak, by current standards, to enable correct identification; moreover, he could not perform chemical tests on the element.<ref name=findingekaiodine>{{cite journal|title= Finding Eka-Iodine: Discovery Priority in Modern Times|first1=S. C.|last1= Burdette|first2= B. F.|last2= Thornton|journal=Bulletin for the History of Chemistry |year=2010 |volume=35 |pages=86–96|url=http://www.scs.illinois.edu/~mainzv/HIST/bulletin_open_access/v35-2/v35-2%20p86-96.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.scs.illinois.edu/~mainzv/HIST/bulletin_open_access/v35-2/v35-2%20p86-96.pdf |archive-date=2022-10-09 |url-status=live}}</ref> He had also been involved in an earlier [[Francium#Erroneous and incomplete discoveries|false claim]] as to the discovery of element 87 (francium) and this is thought to have caused other researchers to downplay his work.<ref>{{cite book| title = A Tale of 7 Elements| year = 2013| edition = Google Play| pages = [https://archive.org/details/taleofseveneleme0000scer/page/188 188–190, 206]| first1 = E.| last1 = Scerri| publisher = Oxford University Press| isbn = 978-0-19-539131-2| url = https://archive.org/details/taleofseveneleme0000scer/page/188}}</ref>
[[File:Segre.jpg|thumb|upright|alt=A greyscale photo of the upper body of a man|[[Emilio Segrè]], one of the discoverers of the [[main-group element]] astatine]]

In 1940, the Swiss chemist [[Walter Minder]] announced the discovery of element 85 as the beta [[decay product]] of radium A (polonium-218), choosing the name "helvetium" (from {{lang|la|[[Helvetia#Name of Switzerland|Helvetia]]}}, the Latin name of Switzerland). [[Berta Karlik]] and Traude Bernert were unsuccessful in reproducing his experiments, and subsequently attributed Minder's results to contamination of his radon stream ([[radon-222]] is the parent isotope of polonium-218).<ref>{{cite journal | doi = 10.1007/BF01487965 | language= de | title = Über Eine Vermutete β-Strahlung des Radium A und die Natürliche Existenz des Elementes 85 | trans-title = About a Suspected β-radiation of Radium A, and the Natural Existence of the Element 85 | year = 1942 | last1 = Karlik | first1 = B.| author-link=Berta Karlik | journal = Naturwissenschaften | volume = 30 | pages = 685–686 | last2 = Bernert | first2 = T.| issue = 44–45|bibcode = 1942NW.....30..685K | s2cid= 6667655 }} {{subscription required}}</ref>{{efn|In other words, some other substance was undergoing beta decay (to a different end element), not polonium-218.}} In 1942, Minder, in collaboration with the English scientist [[Alice Leigh-Smith]], announced the discovery of another isotope of element 85, presumed to be the product of [[Thorium#History|thorium A]] (polonium-216) beta decay. They named this substance "anglo-helvetium",<ref>{{cite journal | title = Experimental Evidence of the Existence of Element 85 in the Thorium Family | author-link1 = Alice Leigh-Smith | first1 = A.| last1 = Leigh-Smith | author-link2 = Walter Minder | first2 = W.| last2 = Minder | journal = Nature | volume = 150 | pages = 767–768 | year = 1942 | doi = 10.1038/150767a0 | issue = 3817|bibcode = 1942Natur.150..767L | s2cid = 4121704 }} {{subscription required}}</ref> but Karlik and Bernert were again unable to reproduce these results.<ref name="Ru1968">{{cite journal | doi = 10.1070/RC1968v037n02ABEH001603 | title = Astatine | year = 1968 | last1= Nefedov | first1 = V. D. | journal = Russian Chemical Reviews | volume = 37 | pages = 87–98 | last2 = Norseev | first2 = Yu. V. | last3 = Toropova | first3 = M. A. | last4 = Khalkin | first4 = Vladimir A. | issue = 2|bibcode = 1968RuCRv..37...87N | s2cid = 250775410 }} {{subscription required}}</ref>

Later in 1940, [[Dale R. Corson]], [[Kenneth Ross MacKenzie]], and [[Emilio Segrè]] isolated the element at the University of California, Berkeley. Instead of searching for the element in nature, the scientists created it by bombarding [[bismuth-209]] with [[alpha particle]]s in a [[cyclotron]] (particle accelerator) to produce, after emission of two neutrons, astatine-211.{{sfn|Corson|MacKenzie|Segrè|1940}} The discoverers, however, did not immediately suggest a name for the element. The reason for this was that at the time, an element created synthetically in "invisible quantities" that had not yet been discovered in nature was not seen as a completely valid one; in addition, chemists were reluctant to recognize radioactive isotopes as legitimately as stable ones.<ref name="Davis-1959">{{Cite book|url=http://nova.wpunj.edu/pardir/Book%20Reviews/The_Chemical_Elements.pdf|title=The Chemical Elements|last=Davis|first=Helen Miles|publisher=[[Science Service]], [[Ballantine Books]]|year=1959|edition=2nd|pages=29|access-date=14 August 2016|archive-url=https://web.archive.org/web/20170823203118/http://nova.wpunj.edu/pardir/Book%20Reviews/The_Chemical_Elements.pdf|archive-date=23 August 2017|url-status=dead}}</ref> In 1943, astatine was found as a product of two naturally occurring [[decay chain]]s by [[Berta Karlik]] and Traude Bernert, first in the so-called [[uranium series]], and then in the [[actinium series]].<ref>{{cite journal | language = de | title = Eine Neue Natürliche α-Strahlung | trans-title = A New Natural α-radiation | last1 = Karlik | first1 = B.| pages = 298–299 | volume = 31 | issue = 25–26 | year = 1943 | journal = Naturwissenschaften | doi = 10.1007/BF01475613 | last2 = Bernert | first2 = T.|bibcode = 1943NW.....31..298K | s2cid = 38193384 }} {{subscription required}}</ref><ref>{{cite journal | language = de | title = Das Element 85 in den Natürlichen Zerfallsreihen | trans-title = The Element 85 in the Natural Decay Chains |journal = Zeitschrift für Physik | volume = 123 | issue = 1–2 | year = 1943 | doi = 10.1007/BF01375144 | pages = 51–72 | last1 = Karlik | first1 = B.| last2 = Bernert | first2 = T.|bibcode = 1944ZPhy..123...51K | s2cid = 123906708 }} {{subscription required}}</ref> (Since then, astatine was also found in a third decay chain, the [[neptunium series]].<ref>{{cite book |first1=C. M.|last1=Lederer|first2=J. M.|last2=Hollander|first3=I.|last3=Perlman |year=1967 |title=Table of Isotopes |edition=6th |pages=1–657|publisher=[[John Wiley & Sons]]}}</ref>) Friedrich Paneth in 1946 called to finally recognize synthetic elements, quoting, among other reasons, recent confirmation of their natural occurrence, and proposed that the discoverers of the newly discovered unnamed elements name these elements. In early 1947, ''[[Nature (journal)|Nature]]'' published the discoverers' suggestions; a letter from Corson, MacKenzie, and Segrè suggested the name "astatine"<ref name="Davis-1959" /> coming from the [[Ancient Greek]] {{Transliteration|grc|astatos}} ({{lang|grc|ἄστατος}}) meaning {{gloss|unstable}}, because of its propensity for [[radioactive decay]], with the ending "-ine", found in the names of the four previously discovered halogens. The name was also chosen to continue the tradition of the four stable halogens, where the name referred to a property of the element.<ref name="Corson2003" />

Corson and his colleagues classified astatine as a metal on the basis of its [[analytical chemistry]].{{sfn|Corson|MacKenzie|Segrè|1940|pp=672, 677}} Subsequent investigators reported iodine-like,<ref>{{cite journal |last1=Hamilton |first1=J. G. |last2=Soley|first2=M. H. |year=1940 |title=A Comparison of the Metabolism of Iodine and of Element 85 (Eka-Iodine)|journal= Proceedings of the National Academy of Sciences|volume=26 |issue=8 |pages=483–489|bibcode = 1940PNAS...26..483H |doi = 10.1073/pnas.26.8.483 |pmc=1078214 |pmid=16588388|doi-access=free }}</ref><ref>{{cite journal |last1=Neumann|first1=H. M.| year=1957| title=Solvent Distribution Studies of the Chemistry of Astatine|journal= Journal of Inorganic and Nuclear Chemistry|volume=4 |issue=5–6 |pages=349–353 |doi=10.1016/0022-1902(57)80018-9 }}</ref> cationic,<ref>{{cite journal |last1=Johnson|first1=G. L. |last2=Leininger |first2=R. F. |last3=Segrè |first3=E. |s2cid=95324453 |year=1949 |title=Chemical Properties of Astatine. I |journal=Journal of Chemical Physics |volume=17 |issue=1 |pages=1–10|doi=10.1063/1.1747034 |bibcode = 1949JChPh..17....1J |hdl=2027/mdp.39015086446914 |hdl-access=free }}</ref><ref>{{cite journal |last1=Dreyer|first1=I. |last2=Dreyer|first2=R. |last3=Chalkin|first3=V. A. |year=1979 |title=Cations of Astatine in Aqueous Solutions; Production and some Characteristics |journal=Radiochemical and Radioanalytical Letters |language=de|volume=36 |issue=6|pages=389–398}}</ref> or [[amphoteric]] behavior.<ref name="Aten">{{cite book |last1=Aten| first1=A. H. W. Jr. |year=1964 |title=The Chemistry of Astatine |volume=6 |pages=207–223 | doi=10.1016/S0065-2792(08)60227-7|series=Advances in Inorganic Chemistry and Radiochemistry|isbn=978-0-12-023606-0}}</ref><ref name="Ru1968"/> In a 2003 retrospective, Corson wrote that "some of the properties [of astatine] are similar to iodine&nbsp;... it also exhibits metallic properties, more like its metallic neighbors Po and Bi."<ref name="Corson2003">{{cite journal |last1=Corson |first1=D. R. |year=2003 |title=Astatine |journal=Chemical & Engineering News |volume=81 |issue=36 |pages=158 |url=http://pubs.acs.org/cen/80th/print/astatine.html|doi=10.1021/cen-v081n036.p158 }}</ref>