Editing Technetium (section)

==History==

===Early assumptions===
From the 1860s through 1871, early forms of the periodic table proposed by [[Dmitri Mendeleev]] contained a gap between [[molybdenum]] (element&nbsp;42) and [[ruthenium]] (element&nbsp;44). In 1871, Mendeleev predicted this missing element would occupy the empty place below [[manganese]] and have similar chemical properties. Mendeleev gave it the provisional name ''eka-manganese'' (from ''eka'', the [[Sanskrit]] word for ''one'') because it was one place down from the known element manganese.<ref>{{cite journal|doi = 10.1007/BF00837634|title = Technetium, the missing element|date = 1996|last1 = Jonge|journal = European Journal of Nuclear Medicine|volume = 23|pages = 336–44|pmid = 8599967|last2 = Pauwels|first2 = E. K.|issue = 3|s2cid = 24026249}}</ref>

=== Early misidentifications ===
Many early researchers, both before and after the periodic table was published, were eager to be the first to discover and name the missing element. Its location in the table suggested that it should be easier to find than other undiscovered elements. This turned out not to be the case, due to technetium's radioactivity.

{| class="wikitable"
! Year
! Claimant
! Suggested name
! Actual material
|-
|1828
|[[Gottfried Osann]]
|[[Polinium]]
|[[Iridium]]
|-
|1845
|[[Heinrich Rose]]
|[[Pelopium]]<ref name="history-origin">{{cite news| title = History of the Origin of the Chemical Elements and Their Discoverers|url = http://www.nndc.bnl.gov/content/elements.html|access-date = 2009-05-05| first = N. E.|last = Holden| publisher = Brookhaven National Laboratory}}</ref>
|Niobium–tantalum alloy

|-
|1847
|R. Hermann
|[[Ilmenium]]<ref>{{cite journal|doi = 10.1002/prac.184704001110|title = Untersuchungen über das Ilmenium|year = 1847|last = Hermann |first=R.|journal = Journal für Praktische Chemie|volume = 40|pages = 457–480|url = https://zenodo.org/record/1427800}}</ref>
|[[Niobium]]–[[tantalum]] [[alloy]]
|-
|1877
|Serge Kern
|[[Davyum]]
|[[Iridium]]–[[rhodium]]–[[iron]] alloy
|-
|1896
|Prosper Barrière
|[[Lucium]]
|[[Yttrium]]
|-
|1908
|[[Masataka Ogawa]]
|[[Nipponium]]
|[[Rhenium]], which was the unknown [[Mendeleev's predicted elements|dvi]]-manganese<ref>{{cite journal|title=Discovery of a new element 'nipponium': re-evaluation of pioneering works of Masataka Ogawa and his son Eijiro Ogawa|journal=Spectrochimica Acta Part B|date=2004|first=H. K.| last=Yoshihara |volume=59 |issue=8 |pages=1305–1310 |doi=10.1016/j.sab.2003.12.027 |bibcode=2004AcSpB..59.1305Y}}</ref><ref name=nipponium2022>{{cite journal |last1=Hisamatsu |first1=Yoji |last2=Egashira |first2=Kazuhiro |first3=Yoshiteru |last3=Maeno |date=2022 |title=Ogawa's nipponium and its re-assignment to rhenium |journal=Foundations of Chemistry |volume=24 |issue= |pages=15–57 |doi=10.1007/s10698-021-09410-x |doi-access=free }}</ref>
|}

===Irreproducible results===
[[File:Periodisches System der Elemente (1904-1945, now Gdansk University of Technology).jpg|thumb|right|{{lang|de|Periodisches System der Elemente}} (Periodic system of the elements) (1904–1945, now at the [[Gdańsk University of Technology]]): lack of elements: [[polonium]] {{sup|84}}Po (though discovered as early as in 1898 by [[Marie Curie|Maria Sklodowska-Curie]]), [[astatine]] {{sup|85}}At (1940, in Berkeley), [[francium]] {{sup|87}}Fr (1939, in France), neptunium {{sup|93}}Np (1940, in Berkeley) and other [[actinide]]s and [[lanthanide]]s. Uses old symbols for: [[argon]] {{sup|18}}Ar (here: A), '''technetium {{sup|43}}Tc''' (Ma, masurium), [[xenon]] {{sup|54}}Xe (X), [[radon]] {{sup|86}}Rn (Em, emanation).]]

German chemists [[Walter Noddack]], [[Otto Berg (scientist)|Otto Berg]], and [[Ida Tacke]] reported the discovery of element&nbsp;75 and element&nbsp;43 in 1925, and named element&nbsp;43 ''masurium'' (after [[Masuria]] in eastern [[Prussia]], now in [[Poland]], the region where Walter Noddack's family originated).<ref name=multidict/> This name caused significant resentment in the scientific community, because it was interpreted as referring to a [[First Battle of the Masurian Lakes|series]] of [[Second Battle of the Masurian Lakes|victories]] of the German army over the Russian army in the Masuria region during World War I; as the Noddacks remained in their academic positions while the Nazis were in power, suspicions and hostility against their claim for discovering element&nbsp;43 continued.<ref name=Scerri/> The group bombarded [[columbite]] with a beam of [[electron]]s and deduced element&nbsp;43 was present by examining [[X-ray]] emission [[spectrogram]]s.{{sfn|Emsley|2001|p=423}} The [[wavelength]] of the X-rays produced is related to the atomic number by a [[Moseley's law|formula]] derived by [[Henry Moseley]] in 1913. The team claimed to detect a faint X-ray signal at a wavelength produced by element&nbsp;43. Later experimenters could not replicate the discovery, and it was dismissed as an error.<ref name="armstrong">{{cite journal |last=Armstrong |first=J.T. |date=2003 |title=Technetium |journal=Chemical & Engineering News |volume=81 |issue=36 |pages=110 |doi=10.1021/cen-v081n036.p110 |url=http://pubs.acs.org/cen/80th/technetium.html |access-date=2009-11-11}}</ref><ref>{{cite news|first=K. A.|last=Nies |date=2001 |title=Ida Tacke and the warfare behind the discovery of fission |url=http://www.hypatiamaze.org/ida/tacke.html |access-date=2009-05-05 |url-status=dead |archive-url= https://web.archive.org/web/20090809125217/http://www.hypatiamaze.org/ida/tacke.html |archive-date = 2009-08-09}}</ref> Still, in 1933, a series of articles on the discovery of elements quoted the name ''masurium'' for element&nbsp;43.<ref>{{cite journal |last = Weeks |first = M.E. |date = 1933 |title = The discovery of the elements. XX. Recently discovered elements |journal = Journal of Chemical Education |volume = 10 |issue = 3 |pages = 161–170|doi = 10.1021/ed010p161 |bibcode = 1933JChEd..10..161W }}</ref> Some more recent attempts have been made to rehabilitate the Noddacks' claims, but they are disproved by [[Paul Kuroda]]'s study on the amount of technetium that could have been present in the ores they studied: it could not have exceeded {{nobr|3 × {{10^|−11}} μg/kg}} of ore, and thus would have been undetectable by the Noddacks' methods.<ref name=Scerri>{{cite book |first=Eric |last=Scerri |author-link=Eric Scerri |title=A tale of seven elements |publisher=Oxford University Press |year=2013 |isbn=978-0-19-539131-2 |pages=109–114, 125–131}}</ref><ref>{{cite journal |last1=Habashi |first1=Fathi |date=2006 |title=The History of Element 43—Technetium |url=https://pubs.acs.org/doi/pdf/10.1021/ed083p213.1 |journal=Journal of Chemical Education |volume=83 |issue=2 |pages=213 |doi=10.1021/ed083p213.1 |bibcode=2006JChEd..83..213H |access-date=2 January 2023}}</ref>

===Official discovery and later history===
The [[Discovery of the chemical elements|discovery]] of element&nbsp;43 was finally confirmed in a 1937 experiment at the [[University of Palermo]] in Sicily by [[Carlo Perrier]] and [[Emilio Segrè]].<ref>{{cite book |last=Heiserman |first=D. L. |year=1992 |chapter=Element&nbsp;43: Technetium |title=Exploring Chemical Elements and their Compounds |location=New York, NY |publisher=TAB Books |isbn=978-0-8306-3018-9 |chapter-url=https://archive.org/details/exploringchemica01heis |page=164}}</ref> In mid-1936, Segrè visited the United States, first [[Columbia University]] in New York and then the [[Lawrence Berkeley National Laboratory]] in California. He persuaded [[cyclotron]] inventor [[Ernest Lawrence]] to let him take back some discarded cyclotron parts that had become [[radioactive]]. Lawrence mailed him a [[molybdenum]] foil that had been part of the deflector in the cyclotron.<ref>{{cite book |first=Emilio |last=Segrè |date=1993 |title=A Mind Always in Motion: The autobiography of Emilio Segrè |publisher=University of California Press |location=Berkeley, CA |isbn=978-0520076273 |pages=[https://archive.org/details/mindalwaysinmoti00segr/page/115 115–118] |url=https://archive.org/details/mindalwaysinmoti00segr/page/115 }}</ref>

Segrè enlisted his colleague Perrier to attempt to prove, through comparative chemistry, that the molybdenum activity was indeed from an element with the atomic number 43. In 1937, they succeeded in isolating the [[isotope]]s [[technetium-95]]m and [[technetium-97]].<ref name=segre/><ref name=blocks>{{harvnb|Emsley|2001|pp=[https://archive.org/details/naturesbuildingb0000emsl/page/422 422]–425}}</ref>{{Disputed inline|First isotopes known|date=April 2024}} [[University of Palermo]] officials wanted them to name their discovery {{lang|la|panormium}}, after the Latin name for [[Palermo]], ''{{lang|la|Panormus}}''. In 1947,<ref name=segre>{{cite journal |last1= Perrier |first1= C. |last2= Segrè |first2= E. |date= 1947 |title=Technetium: The element of atomic number&nbsp;43 |journal= Nature |volume= 159 |issue= 4027 |page= 24 |doi= 10.1038/159024a0 |pmid= 20279068 |bibcode= 1947Natur.159...24P |s2cid= 4136886}}</ref> element 43 was named after the [[Greek language|Greek]] word {{Transliteration|el|technetos}} ({{lang|el|τεχνητός}}), meaning 'artificial', since it was the first element to be artificially produced.<ref name=history-origin/><ref name=multidict>
{{cite web
 |last=van der Krogt |first=P.
 |series=Elentymolgy and Elements Multidict
 |title=Technetium
 |url=http://elements.vanderkrogt.net/element.php?sym=Tc
 |access-date=2009-05-05
}}
</ref>
Segrè returned to Berkeley and met [[Glenn T. Seaborg]]. They isolated the [[metastable isotope]] [[technetium-99m]], which is now used in some ten million medical diagnostic procedures annually.<ref>
{{cite book
 |last1=Hoffman |first1=Darleane C.
 |last2=Ghiorso |first2=Albert
 |last3=Seaborg |first3=Glenn T.
 |date =2000
 |chapter=Chapter&nbsp;1.2: Early days at the Berkeley Radiation Laboratory
 |title=The Transuranium People: The inside story
 |series = [[Lawrence Berkeley National Laboratory]]
 |publisher = University of California Press
 |place = Berkeley, CA
 |isbn=978-1-86094-087-3
 |page =15
 |chapter-url =http://www.worldscibooks.com/physics/p074.html
 |access-date = 2007-03-31 |url-status=dead
 |archive-url =https://web.archive.org/web/20070124220556/http://www.worldscibooks.com/physics/p074.html
 |archive-date=2007-01-24
}}
</ref>

In 1952, the astronomer [[Paul W. Merrill]] detected the [[emission spectrum|spectral signature]] of technetium (specifically [[wavelength]]s of 403.1&nbsp;[[Nanometre|nm]], 423.8&nbsp;nm, 426.2&nbsp;nm, and 429.7&nbsp;nm) in light from [[Stellar classification#Class S|S-type]] [[red giant]]s.<ref>{{cite journal |last=Merrill |first=P.W. |date=1952 |title=Technetium in the stars |journal=Science |volume=115 |issue=2992|pages=479–489, esp.&nbsp;484 |doi=10.1126/science.115.2992.479|pmid=17792758 |bibcode=1952Sci...115..479. }}</ref> The stars were near the end of their lives but were rich in the short-lived element, which indicated that it was being produced in the stars by [[nuclear reaction]]s. That evidence bolstered the hypothesis that heavier elements are the product of [[nucleosynthesis]] in stars.<ref name=blocks/> More recently, such observations provided evidence that elements are formed by [[neutron capture]] in the [[s-process]].<ref name=s8>{{harvnb|Schwochau|2000|pp=7–9}}</ref>

Since that discovery, there have been many searches in terrestrial materials for natural sources of technetium. In 1962, technetium-99 was isolated and identified in [[uraninite|pitchblende]] from the [[Belgian Congo]] in very small quantities (about 0.2&nbsp;ng/kg),<ref name=s8/> where it originates as a [[spontaneous fission]] product of [[uranium-238]]. The [[natural nuclear fission reactor]] in [[Oklo]] contains evidence that significant amounts of technetium-99 were produced and have since decayed into [[ruthenium-99]].<ref name=s8/>