Technetium: Difference between revisions - Wikipedia

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{{Short description|Chemical element, symbol Tc & atomic number 43}}

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{{Infobox technetium}}

'''Technetium''' is a [[chemical element]]; it has [[Symbol (chemistry)|symbol]] '''Tc''' and [[atomic number]] 43. It is the lightest element whose [[isotopes]] are all [[radioactive]]. Technetium and [[promethium]] are the only radioactive elements whose neighbours in the sense of atomic number are both stable. All available technetium is produced as a [[synthetic element]]. Naturally occurring technetium is a spontaneous [[fission product]] in [[uranium ore]] and [[thorium]] ore (the most common source), or the product of [[neutron capture]] in [[molybdenum]] ores. This silvery gray, crystalline [[transition metal]] lies between [[manganese]] and [[rhenium]] in [[group 7 element|group  7]] of the [[periodic table]], and its chemical properties are intermediate between those of both adjacent elements. The most common naturally occurring isotope is ⁹⁹Tc, in traces only.

Many of technetium's properties had been predicted by [[Dmitri Mendeleev]] before it was discovered.; Mendeleev noted a gap in his periodic table and gave the undiscovered element the provisional name ''[[Mendeleev's predicted elements|ekamanganese]]'' (''Em''). In 1937, technetium became the first predominantly artificial element to be produced, hence its name (from the Greek ''{{transl|el|technetos}}'', {{lang|el|τεχνητός}}, from {{transl|el|techne}}, as in "craft", "art" and having the meaning of "'artificial"', + {{nowrap|''[[wikt:-ium#Suffix|-ium]]'').}}

One short-lived [[gamma ray]]-emitting–emitting [[nuclear isomer]], [[technetium-99m]], is used in [[nuclear medicine]] for a wide variety of tests, such as bone cancer diagnoses. The ground state of the [[nuclide]] [[technetium-99]] is used as a gamma-ray-free ray–free source of [[beta particle]]s. Long-lived [[isotopes of technetium|technetium isotopes]] produced commercially are byproducts of the [[nuclear fission|fission]] of [[uranium-235]] in [[nuclear reactors]] and are extracted from [[nuclear fuel cycle|nuclear fuel rods]]. Because even the longest-lived isotope of technetium has a relatively short [[half-life]] (4.21 million years), the 1952 detection of technetium in [[red giant]]s helped to prove that stars can [[nuclear fusion|produce heavier elements]].

==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 ''ekamanganeseeka-manganese'' (from ''eka''-, the [[Sanskrit]] word for ''one'') because the predicted elementit 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"

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|[[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=2004AcSpe2004AcSpB..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: 84 [[polonium]] {{sup|84}}Po (though discovered as early as in 1898 by [[Marie Curie|Maria Sklodowska-Curie]]), 85 [[astatine]] {{sup|85}}At (1940, in Berkeley), 87 [[francium]] {{sup|87}}Fr (1939, in France), 93 neptunium {{sup|93}}Np (1940, in Berkeley) and other actinides[[actinide]]s and lanthanides[[lanthanide]]s. OldUses old symbols for: 18 [[argon]] {{sup|18}}Ar (here: A), 43 '''[[technetium]] {{sup|43}}Tc''' (Ma, masurium), 54 [[xenon]] {{sup|54}}Xe (X), 86 [[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. |doidate=10.1021/cen-v081n036.p1102003 |title=Technetium |journal=Chemical & Engineering News |volume=81 |issue=36 |pages=110 |datedoi=200310.1021/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 |urldate=http://www.hypatiamaze.org/ida/tacke.html2001 |title=Ida Tacke and the warfare behind the discovery of fission |dateurl=2001http://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|last = Weeks|first = M. E.|journal = Journal of Chemical Education |datevolume = 193310 |issue = 3 |pages = 161–170|doi = 10.1021/ed010p161 |volume = 10|issue = 3|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|isbn=978-0-19-539131-2}}, pp. |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=Element 43: Technetium |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 Autobiographyautobiography of Emilio Segrè |publisher=University of California Press |location=Berkeley, CaliforniaCA |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 |doilast1= 10.1038/159024a0Perrier |pmidfirst1= 20279068C. |titlelast2= Technetium:Segrè The|first2= ElementE. of Atomic Number 43|date= 1947 |last1title=Technetium: Perrier|first1=The C.|last2=element Segrè|first2=of atomic number&nbsp;43 E.|journal= Nature |volume= 159 |issue= 4027 |pagespage= 24 |doi= 10.1038/159024a0 |pmid= 20279068 |bibcode= 1947Natur.159...24P |s2cid= 4136886}}</ref> element 43 was named after the [[Greek language|Greek]] word ''{{transl|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.| work=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|title= The Transuranium People: The Inside Story|publisher =University of California, Berkeley & Lawrence Berkeley National Laboratory|last1=Hoffman |first1=Darleane C. |last2=Ghiorso |first2=Albert |last3=Seaborg |first3=Glenn T. |date =2000|chapter =Chapter 1.2: Early Days at the Berkeley Radiation Laboratory|page =15|chapter-url =http://www.worldscibooks.com/physics/p074.html|isbn=978-1-86094-087-3 |access-date=2007-03-31|url-status=dead|archive-date=2007-01-24 |archive-url =https://web.archive.org/web/20070124220556/http://www.worldscibooks.com/physics/p074.html}}</ref>

{{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]] in California 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] |date=1952 |title=Technetium in the stars|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 [[Oklo]] [[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" />

==Characteristics==

===Physical properties===

Technetium is a silvery-gray radioactive [[metal]] with an appearance similar to [[platinum]], commonly obtained as a gray powder.{{sfn|Hammond|2004|p={{page needed|date=June 2021}}}} The [[crystal structure]] of the bulk pure metal is [[Hexagonal crystal system|hexagonal]] [[close-packed]], and crystal structures of the nanodisperse pure metal are [[Cubic crystal system|cubic]]. Nanodisperse technetium does not have a split NMR spectrum, while hexagonal bulk technetium has the Tc-99-NMR spectrum split in 9 satellites.{{sfn|Hammond|2004|p={{page needed|date=June 2021}}}}<ref>{{cite journal |last1=Tarasov |first1=V.P. |last2=Muravlev |first2=Yu. B. |last3=German |first3=K. E. |last4=Popova |first4=N. N. |date=2001 |title=⁹⁹Tc NMR of Supported Technetium Nanoparticles |journal=Doklady Physical Chemistry |volume=377 |number=1–3 |date=2001 |pages=71–76 |doi=10.1023/A:1018872000032 |s2cid=91522281 |url=https://www.researchgate.net/publication/251379398}}</ref> Atomic technetium has characteristic [[Emission spectrum|emission lines]] at [[wavelength]]s of 363.3&nbsp;[[Nanometre|nm]], 403.1&nbsp;nm, 426.2&nbsp;nm, 429.7&nbsp;nm, and 485.3&nbsp;nm.<ref>{{cite book | title first=David The CRCR. Handbook| publisherlast=Lide |date =CRC press2004–2005 |chapter = Line Spectraspectra of the Elementselements |title date= The CRC Handbook |publisher =CRC press |pages=10–70 (1672) | isbn=978-0-8493-0595-5 2004–2005|chapter-url=https://books.google.com/books?id=q2qJId5TKOkC&pg=PT1672 |pages=10–70 (1672) | first=David R. | last=Lide | isbn=978-0-8493-0595-5}}</ref> The unit cell parameters of the orthorhombic Tc metal were reported when Tc is contaminated with carbon ({{mvar|a}} = 0.2805(4), {{mvar|b}} = 0.4958(8), {{mvar|c}} = 0.4474(5)·nm for Tc-C with 1.38 wt% C and {{mvar|a}} = 0.2815(4), {{mvar|b}} = 0.4963(8), {{mvar|c}} = 0.4482(5) •nm for Tc-C with 1.96 wt% C ).<ref>{{Cite journal |last1name=German |first1=K. E. |last2=Peretrukhin |first2=V. F. |last3=Gedgovd |first3=K. N. |last4=Grigoriev |first4=M. S. |last5=Tarasov |first5=A. V. |last6=Plekhanov |first6=Yu V. |last7=Maslennikov |first7=A. G. |last8=Bulatov |first8=G. S. |last9=Tarasov |first9=V. P. |last10=Lecomte |first10=M. |date=2005 |title=Tc Carbide and New Orthorhombic Tc Metal Phase |url=https:"carbide"//www.jstage.jst.go.jp/article/jnrs2000/6/3/6_3_211/_article |journal=Journal of Nuclear and Radiochemical Sciences |volume=6 |issue=3 |pages=211–214 |doi=10.14494/jnrs2000.6.3_211|doi-access=free }}</ref> The metal form is slightly [[paramagnetism|paramagnetic]], meaning its [[dipole|magnetic dipoles]] align with external [[magnetic field]]s, but will assume random orientations once the field is removed.<ref name="enc">{{cite book |last=Rimshaw title|first=The EncyclopediaS.J. of the Chemical Elements|date=1968 |editor-last=Hampel, |editor-first=C. A.| last=Rimshaw |firsttitle=S.The J.|Encyclopedia of the Chemical Elements |location=New York|, NY |publisher=Reinhold Book Corporation| date=1968| url=https://archive.org/details/encyclopediaofch00hamp| |url-access=registration| |pages=[https://archive.org/details/encyclopediaofch00hamp/page/689 689–693] }}</ref> Pure, metallic, single-crystal technetium becomes a [[type-II superconductor]] at temperatures below 7.46&nbsp;[[Kelvin|K]].{{sfn|Schwochau|2000|p=96}}{{efn|
Irregular crystals and trace impurities raise this transition temperature to 11.2&nbsp;K for 99.9% pure technetium powder.{{sfn|Schwochau|2000|p=96}}
}}
Below this temperature, technetium has a very high [[London penetration depth|magnetic penetration depth]], greater than any other element except [[niobium]].<ref>{{cite newsconference |last = Autler |first=S.H. |date=Summer 1968 |title = Technetium as a Materialmaterial for AC Superconductivitysuperconductivity Applications| last = Autlerapplications |first=S. H.| publisherconference = Proceedings of the 1968 Summer Study on Superconducting Devices and Accelerators|access-date = 2009-05-05|date=1968| url = http://www.bnl.gov/magnets/Staff/Gupta/Summer1968/0049.pdf |access-date = 2009-05-05}}</ref>

===Chemical properties===

Technetium is located in the [[Group 7 element|seventh group&nbsp;7]] of the periodic table, between [[rhenium]] and [[manganese]]. As predicted by the [[History of the periodic table|periodic law]], its chemical properties are between those two elements. Of the two, technetium more closely resembles rhenium, particularly in its chemical inertness and tendency to form [[covalent bond]]s.{{sfn|Greenwood|Earnshaw|1997|p=1044}} This is consistent with the tendency of [[period 5 element|period&nbsp;5 elements]]s to resemble their counterparts in period &nbsp;6 more than period &nbsp;4 due to the [[lanthanide contraction]]. Unlike manganese, technetium does not readily form [[cation]]s ([[ion]]s with a net positive charge). Technetium exhibits nine [[oxidation state]]s from −1 to +7, with +4, +5, and +7 being the most common.<ref name="LANL" /> Technetium dissolves in [[aqua regia]], [[nitric acid]], and concentrated [[sulfuric acid]], but it is ''not soluble'' in [[hydrochloric acid]] of any concentration.{{sfn|Hammond|2004|p={{page needed|date=June 2021}}}}

Metallic technetium slowly [[tarnish]]es in moist air<ref name="LANL">{{cite web |titlelast=TechnetiumHusted |urlfirst=http://periodicR.lanl.gov/43.shtml|publisher=Los Alamos National Laboratory|date=2003-12-15 |title=Technetium |workseries=Periodic Table of the Elements |lastpublisher=Husted[[Los Alamos National Laboratory]] |firstplace=RLos Alamos, NM |url=http://periodic.lanl.gov/43.shtml |access-date=2009-10-11}}</ref> and, in powder form, burns in [[oxygen]]. When reacting with [[hydrogen]] at high pressure, it forms the hydride TcH1TcH{{sub|1.3}}<ref name="Zhou 2023">{{Citecite journal |last1=Zhou |first1=Di |last2=Semenok |first2=Dmitrii V. |last3=Volkov |first3=Mikhail A. |last4=Troyan |first4=Ivan A. |last5=Seregin |first5=Alexey Yu. |last6=Chepkasov |first6=Ilya V. |last7=Sannikov |first7=Denis A. |last8=Lagoudakis |first8=Pavlos G. |last9=Oganov |first9=Artem R. |last10=German |first10=Konstantin E. |display-authors=6 |date=2023-02-06 |title=<nowiki>Synthesis of technetium hydride $\mathrm{Tc}{\mathrm{H}}_{TcH_1.3}$ at 27 &nbsp;GPa</nowiki> |url=https://link.aps.org/doi/10.1103/PhysRevB.107.064102 |journal=Physical Review B |volume=107 |issue=6 |pagespage=064102 |doi=10.1103/PhysRevB.107.064102 |arxiv=2210.01518 |bibcode=2023PhRvB.107f4102Z }}</ref> and while reacting with [[carbon]] it forms Tc<{{sub>|6</sub>}}C,<ref name=carbide>{{Citecite journal |last1=German |first1=K. E. |last2=Peretrukhin |first2=V. F. |last3=Gedgovd |first3=K. N. |last4=Grigoriev |first4=M. S. |last5=Tarasov |first5=A. V. |last6=Plekhanov |first6=Yu V. |last7=Maslennikov |first7=A. G. |last8=Bulatov |first8=G. S. |last9=Tarasov |first9=V. P. |last10=Lecomte |first10=M. |display-authors=6 |date=2005 |title=Tc Carbidecarbide and Newnew Orthorhombicorthorhombic Tc Metalmetal Phase |url=https://www.jstage.jst.go.jp/article/jnrs2000/6/3/6_3_211/_articlephase |journal=Journal of Nuclear and Radiochemical Sciences |volume=6 |issue=3 |pages=211–214 |doi=10.14494/jnrs2000.6.3_211 |doi-access=free |url=https://www.jstage.jst.go.jp/article/jnrs2000/6/3/6_3_211/_article }}</ref> with cell parameter 30.98398&nbsp;Ånm, as well as the nanodisperce low-carbon-content carbide with parameter 40.02&nbsp;Å402nm.<ref>{{Citecite journal |last1=Kuznetsov |first1=Vitaly V. |last2=German |first2=Konstantin E. |last3=Nagovitsyna |first3=Olga A. |last4=Filatova |first4=Elena A. |last5=Volkov |first5=Mikhail A. |last6=Sitanskaia |first6=Anastasiia V. |last7=Pshenichkina |first7=Tatiana V. |date=2023-10-31 |title=Route to Stabilizationstabilization of Nanotechnetiumnano-technetium in an Amorphousamorphous Carboncarbon Matrixmatrix: Preparative Methodsmethods, XAFS Evidenceevidence, and Electrochemicalelectrochemical Studiesstudies |url=https://pubs.acs.org/doi/10.1021/acs.inorgchem.3c03001 |journal=Inorganic Chemistry |volume=62 |issue=45 |pages=18660–18669 |language=en |doi=10.1021/acs.inorgchem.3c03001 |pmid=37908073 |issn=0020-1669}}</ref>

Technetium can catalyse the destruction of [[hydrazine]] by [[nitric acid]], and this property is due to its multiplicity of valencies.<ref>{{cite journal | doi = 10.1016/0022-5088(84)90023-7 | title=The technetium-catalysed oxidation of hydrazine by nitric acid | journal=Journal of the Less Common Metals | date=1984 | volume=97 | pages=191–203 | first=John | last=Garraway}}</ref> This caused a problem in the separation of plutonium from uranium in [[Nuclear reprocessing|nuclear fuel processing]], where hydrazine is used as a protective reductant to keep plutonium in the trivalent rather than the more stable tetravalent state. The problem was exacerbated by the mutually enhanced solvent extraction of technetium and zirconium at the previous stage,<ref>{{cite journal | doi = 10.1016/0022-5088(85)90379-0 | title=Coextraction of pertechnetate and zirconium by tri-n-butyl phosphate | journal=Journal of the Less Common Metals | date=1985 | volume=106 | issue=1 | pages=183–192 | first=J. | last=Garraway}}</ref> and required a process modification.

==Compounds==

===Pertechnetate and other derivatives===

{{main|Pertechnetate}}

[[File:Pertechnetate1.svg|thumb|left|upright|Pertechnetate is one of the most available forms of technetium. It is structurally related to [[permanganate]].]]

The most prevalent form of technetium that is easily accessible is [[sodium pertechnetate]], Na[TcO₄]. The majority of this material is produced by radioactive decay from [⁹⁹MoO₄]²⁻:{{sfn|Schwochau|2000|pp=127–136}}<ref name="nuclmed" />

:[⁹⁹MoO₄]²⁻ → [^99mTcO₄]⁻ + e⁻

{{block indent|[⁹⁹MoO₄]²⁻ → [^99mTcO₄]⁻ + e⁻}}

[[Pertechnetate]] ({{chem|TcO|4|-}}) is only weakly hydrated in aqueous solutions,<ref>{{Cite journal |last1=Ustynyuk |first1=Yuri A. |last2=Gloriozov |first2=Igor P. |last3=Zhokhova |first3=Nelly I. |last4=German |first4=Konstantin E. |last5=Kalmykov |first5=Stepan N. |date=2021-11-15 |title=Hydration of the pertechnetate anion. DFT study |url=https://www.sciencedirect.com/science/article/pii/S0167732221021280 |journal=Journal of Molecular Liquids |volume=342 |pages=117404 |doi=10.1016/j.molliq.2021.117404 |issn=0167-7322}}</ref> and it behaves analogously to perchlorate anion, both of which are [[tetrahedral molecular geometry|tetrahedral]]. Unlike [[permanganate]] ({{chem|MnO|4|-}}), it is only a weak [[oxidizing agent]].

[[Pertechnetate]] ({{chem|TcO|4|-}}) is only weakly hydrated in aqueous solutions,<ref>{{cite journal |last1=Ustynyuk |first1=Yuri A. |last2=Gloriozov |first2=Igor P. |last3=Zhokhova |first3=Nelly I. |last4=German |first4=Konstantin E. |last5=Kalmykov |first5=Stepan N. |date=2021-11-15 |title=Hydration of the pertechnetate anion. DFT study |journal=Journal of Molecular Liquids |volume=342 |page=117404 |doi=10.1016/j.molliq.2021.117404 |issn=0167-7322 |url=https://www.sciencedirect.com/science/article/pii/S0167732221021280 }}</ref> and it behaves analogously to perchlorate anion, both of which are [[tetrahedral molecular geometry|tetrahedral]]. Unlike [[permanganate]] ({{chem|MnO|4|-}}), it is only a weak [[oxidizing agent]].

Related to pertechnetate is [[Technetium(VII) oxide|technetium heptoxide]]. This pale-yellow, volatile solid is produced by oxidation of Tc metal and related precursors:

:4 Tc + 7 O₂ → 2 Tc₂O₇

It is a molecular metal oxide, analogous to [[manganese heptoxide]]. It adopts a [[Centrosymmetry|centrosymmetric]] structure with two types of Tc−O bonds with 167 and 184&nbsp;pm bond lengths.<ref>{{cite journal|last = Krebs|first = B.|title = Technetium(VII)-oxid: Ein Übergangsmetalloxid mit Molekülstruktur im festen Zustand (Technetium(VII) Oxide, a Transition Metal Oxide with a Molecular Structure in the Solid State)|journal = Angewandte Chemie|date = 1969|volume = 81|pages = 328–329|doi = 10.1002/ange.19690810905|issue = 9}}</ref>

{{block indent|4 Tc + 7 O₂ → 2 Tc₂O₇}}

Technetium heptoxide hydrolyzes to pertechnetate and [[pertechnetic acid]], depending on the pH:{{sfn|Schwochau|2000|p=127}}<ref>{{cite book|last1=Herrell |first1=A. Y. |last2=Busey |first2=R. H. |last3=Gayer |first3=K. H. |title=Technetium(VII) Oxide, in Inorganic Syntheses|date=1977|volume=XVII |pages=155–158|isbn=978-0-07-044327-3}}</ref>

:Tc₂O₇ + 2 OH⁻ → 2 TcO₄⁻ + H₂O

:Tc₂O₇ + H₂O → 2 HTcO₄

It is a molecular metal oxide, analogous to [[manganese heptoxide]]. It adopts a [[Centrosymmetry|centrosymmetric]] structure with two types of Tc−O bonds with 167 and 184&nbsp;pm bond lengths.<ref>{{cite journal |last = Krebs |first = B. |date = 1969 |title = Technetium(VII)-oxid: Ein Übergangsmetalloxid mit Molekülstruktur im festen Zustand |language=de |trans-title=Technetium(VII) oxide, a transition metal oxide with a molecular structure in the solid tate |journal = Angewandte Chemie |volume = 81 |issue = 9 |pages = 328–329 |doi = 10.1002/ange.19690810905 | bibcode=1969AngCh..81..328K }}</ref>

HTcO₄ is a strong acid. In concentrated [[sulfuric acid]], [TcO₄]⁻ converts to the octahedral form TcO₃(OH)(H₂O)₂, the conjugate base of the hypothetical tri[[aquo complex]] [TcO₃(H₂O)₃]⁺.<ref>{{cite journal|display-authors=7|author=Poineau F|author2=Weck PF|author3=German K|author4=Maruk A|author5=Kirakosyan G|author6=Lukens W|author7=Rego DB|author8=Sattelberger AP|author9=Czerwinski KR|title=Speciation of heptavalent technetium in sulfuric acid: structural and spectroscopic studies|journal=Dalton Transactions|date=2010|volume=39|issue=37|pages=8616–8619|doi=10.1039/C0DT00695E|url=http://radchem.nevada.edu/docs/pub/tc%20in%20h2so4%20%28dalton%29%202010-08-23.pdf|pmid=20730190|s2cid=9419843|access-date=2011-11-14|archive-date=2017-03-05|archive-url=https://web.archive.org/web/20170305152213/http://radchem.nevada.edu/docs/pub/tc%20in%20h2so4%20%28dalton%29%202010-08-23.pdf|url-status=dead}}</ref>

Technetium heptoxide hydrolyzes to pertechnetate and [[pertechnetic acid]], depending on the pH:{{sfn|Schwochau|2000|p=127}}<ref>{{cite book |last1=Herrell |first1=A.Y. |last2=Busey |first2=R.H. |last3=Gayer |first3=K.H. |date=1977 |title=Technetium(VII) Oxide, in Inorganic Syntheses |volume=XVII |pages=155–158|isbn=978-0-07-044327-3 }}</ref>

{{block indent|Tc₂O₇ + 2 OH⁻ → 2 TcO₄⁻ + H₂O}}

{{block indent|Tc₂O₇ + H₂O → 2 HTcO₄}}

HTcO₄ is a strong acid. In concentrated [[sulfuric acid]], [TcO₄]⁻ converts to the octahedral form TcO₃(OH)(H₂O)₂, the conjugate base of the hypothetical tri[[aquo complex]] [TcO₃(H₂O)₃]⁺.<ref>{{cite journal |display-authors=6 |vauthors=Poineau F, Weck PF, German K, Maruk A, Kirakosyan G, Lukens W, Rego DB, Sattelberger AP, KR |name-list-style=vanc |date=2010 |title=Speciation of heptavalent technetium in sulfuric acid: Structural and spectroscopic studies |journal=Dalton Transactions |volume=39 |issue=37 |pmid=20730190 |s2cid=9419843 |pages=8616–8619|doi=10.1039/C0DT00695E |url=http://radchem.nevada.edu/docs/pub/tc%20in%20h2so4%20%28dalton%29%202010-08-23.pdf |access-date=2011-11-14 |url-status=dead |archive-url=https://web.archive.org/web/20170305152213/http://radchem.nevada.edu/docs/pub/tc%20in%20h2so4%20%28dalton%29%202010-08-23.pdf |archive-date=2017-03-05 }}</ref>

===Other chalcogenide derivatives===

Technetium forms a [[technetium(IV) oxide|dioxide]],{{sfn|Schwochau|2000|p=108}} [[metal dichalcogenide|disulfide]], di[[selenide]], and di[[telluride (chemistry)|telluride]]. An ill-defined Tc₂S₇ forms upon treating [[pertechnate]] with hydrogen sulfide. It thermally decomposes into disulfide and elemental sulfur.{{sfn|Schwochau|2000|pp=112–113}} Similarly the dioxide can be produced by reduction of the Tc₂O₇.

Unlike the case for rhenium, a trioxide has not been isolated for technetium. However, TcO₃ has been identified in the gas phase using [[mass spectrometry]].<ref>{{cite journal |last1=Gibson |first1=John K. |year=1993 |title=High-Temperaturetemperature Oxideoxide and Hydroxidehydroxide Vaporvapor Speciesspecies of Technetiumtechnetium |journal=Radiochimica Acta |volume=60 |issue=2–3|year=1993 |last1=Gibson |first1=John K. |pages=121–126 |doi=10.1524/ract.1993.60.23.121 |s2cid=99795348 }}</ref>

===Simple hydride and halide complexes===

Technetium forms the simple complex {{chem|TcH|9|2-}}. The potassium salt is [[isostructural]] with [[Potassium nonahydridorhenate|{{chem|ReH|9|2-}}]].{{sfn|Schwochau|2000|p=146}} At high pressure formation of TcH1,3 from elements was also reported.<ref>{{Cite journal |last1name="Zhou |first1=Di |last2=Semenok |first2=Dmitrii V. |last3=Volkov |first3=Mikhail A. |last4=Troyan |first4=Ivan A. |last5=Seregin |first5=Alexey Yu. |last6=Chepkasov |first6=Ilya V. |last7=Sannikov |first7=Denis A. |last8=Lagoudakis |first8=Pavlos G. |last9=Oganov |first9=Artem R. |last10=German |first10=Konstantin E. |date=2023-02-06 |title=<nowiki>Synthesis of technetium hydride $\mathrm{Tc}{\mathrm{H}}_{1.3}$ at 27 GPa<"/nowiki> |url=https://link.aps.org/doi/10.1103/PhysRevB.107.064102 |journal=Physical Review B |volume=107 |issue=6 |pages=064102 |doi=10.1103/PhysRevB.107.064102|arxiv=2210.01518 }}</ref>

[[File:Zirconium-tetrachloride-3D-balls-A.png|thumb|TcCl₄ forms chain-like structures, similar to the behavior of several other metal tetrachlorides.]]

The following binary (containing only two elements) technetium halides are known: [[TcF6|TcF₆]], TcF₅, [[TcCl4|TcCl₄]], TcBr₄, TcBr₃, α-TcCl₃, β-TcCl₃, TcI₃, α-TcCl₂, and β-TcCl₂. The [[oxidation state]]s range from Tc(VI) to Tc(II). Technetium halides exhibit different structure types, such as molecular octahedral complexes, extended chains, layered sheets, and metal clusters arranged in a three-dimensional network.<ref>{{cite thesis |last=Johnstone |first=E.V. |date=May 2014 |title=Binary Technetium Halides |publisher=[[University of Nevada]] |place=Las Vegas, NV |doi=10.34917/5836118 |via=UNLV Theses, Dissertations, Professional Papers, and Capstones |url=http://digitalscholarship.unlv.edu/cgi/viewcontent.cgi?article=3100&context=thesesdissertations }}</ref><ref name=AS>{{cite journal |last1=Poineau |first1=Frederic |last2=Johnstone |first2=Erik V. |last3=Czerwinski |first3=Kenneth R. |last4=Sattelberger |first4=Alfred P. |year=2014 |title=Recent advances in technetium halide chemistry |journal=Accounts of Chemical Research |volume=47 |issue=2 |pages=624–632 |doi=10.1021/ar400225b |pmid=24393028 }}</ref> These compounds are produced by combining the metal and halogen or by less direct reactions.

TcCl₄ is obtained by chlorination of Tc metal or Tc₂O₇ Upon heating, TcCl₄ gives the corresponding Tc(III) and Tc(II) chlorides.<ref name=AS/>

The following binary (containing only two elements) technetium halides are known: [[TcF6|TcF₆]], TcF₅, [[TcCl4|TcCl₄]], TcBr₄, TcBr₃, α-TcCl₃, β-TcCl₃, TcI₃, α-TcCl₂, and β-TcCl₂. The [[oxidation state]]s range from Tc(VI) to Tc(II). Technetium halides exhibit different structure types, such as molecular octahedral complexes, extended chains, layered sheets, and metal clusters arranged in a three-dimensional network.<ref>{{Cite thesis|title=Binary Technetium Halides |last=Johnstone|first=E. V. |date=May 2014 |publisher=University of Nevada, Las Vegas |url=http://digitalscholarship.unlv.edu/cgi/viewcontent.cgi?article=3100&context=thesesdissertations |doi=10.34917/5836118 |journal=UNLV Theses, Dissertations, Professional Papers, and Capstones}}</ref><ref name="AS">{{cite journal|doi=10.1021/ar400225b |pmid=24393028|title=Recent Advances in Technetium Halide Chemistry|journal=Accounts of Chemical Research|volume=47|issue=2|pages=624–632 |year=2014|last1=Poineau |first1=Frederic|last2=Johnstone|first2=Erik V.|last3=Czerwinski|first3=Kenneth R.|last4=Sattelberger |first4=Alfred P.}}</ref> These compounds are produced by combining the metal and halogen or by less direct reactions.

{{block indent|TcCl₄ → α-TcCl₃ + 1/2 Cl₂}}

{{block indent|TcCl₃ → β-TcCl₂ + 1/2 Cl₂}}

TcCl₄ is obtained by chlorination of Tc metal or Tc₂O₇ Upon heating, TcCl₄ gives the corresponding Tc(III) and Tc(II) chlorides.<ref name="AS" />

:TcCl₄ → α-TcCl₃ + 1/2 Cl₂

:TcCl₃ → β-TcCl₂ + 1/2 Cl₂

The structure of TcCl₄ is composed of infinite zigzag chains of edge-sharing TcCl₆ octahedra. It is isomorphous to transition metal tetrachlorides of [[zirconium]], [[hafnium]], and [[platinum]].<ref name="AS" />

[[File:Chloro-containing coordination complexes of technetium (Tc-99).jpg|thumb|Chloro-containing coordination complexes of technetium (⁹⁹Tc) in various oxidation states: Tc(III), Tc(IV), Tc(V), and Tc(VI) represented.]]

Two polymorphs of [[technetium trichloride]] exist, α- and β-TcCl₃. The α polymorph is also denoted as Tc₃Cl₉. It adopts a confacial [[Octahedral molecular geometry#Bioctahedral molecular geometry|bioctahedral structure]].<ref>{{cite journal |last1=Poineau |first1=Frederic |last2=Johnstone |first2=Erik V.|last3=Weck |first3=Philippe F. |last4=Kim |first4=Eunja |last5=Forster |first5=Paul M. |last6=Scott |first6=Brian L. |last7=Sattelberger |first7=Alfred P. |last8=Czerwinski |first8=Kenneth R. |display-authors=6 |year=2010 |title=Synthesis and structure of technetium trichloride |journal=Journal of the American Chemical Society |volume=132 |issue=45 |pages=15864–15865 |doi=10.1021/ja105730e |pmid=20977207 }}</ref> It is prepared by treating the chloro-acetate Tc₂(O₂CCH₃)₄Cl₂ with HCl. Like [[Trirhenium nonachloride|Re₃Cl₉]], the structure of the α-polymorph consists of triangles with short M-M distances. β-TcCl₃ features octahedral Tc centers, which are organized in pairs, as seen also for [[molybdenum trichloride]]. TcBr₃ does not adopt the structure of either trichloride phase. Instead it has the structure of [[molybdenum tribromide]], consisting of chains of confacial octahedra with alternating short and long Tc—Tc contacts. TcI₃ has the same structure as the high temperature phase of [[titanium(III) iodide|TiI₃]], featuring chains of confacial octahedra with equal Tc—Tc contacts.<ref name=AS/>

Several anionic technetium halides are known. The binary tetrahalides can be converted to the hexahalides [TcX₆]²⁻ (X = F, Cl, Br, I), which adopt [[octahedral molecular geometry]].<ref name=s8/> More reduced halides form anionic clusters with Tc–Tc bonds. The situation is similar for the related elements of Mo, W, Re. These clusters have the nuclearity Tc₄, Tc₆, Tc₈, and Tc₁₃. The more stable Tc₆ and Tc₈ clusters have prism shapes where vertical pairs of Tc atoms are connected by triple bonds and the planar atoms by single bonds. Every technetium atom makes six bonds, and the remaining valence electrons can be saturated by one axial and two [[bridging ligand]] halogen atoms such as [[chlorine]] or [[bromine]].<ref>{{cite journal |first1 = K.E. |last1 = German |last2 = Kryutchkov|first2 = S.V. |date = 2002 |title = Polynuclear technetium halide clusters |journal = Russian Journal of Inorganic Chemistry |volume = 47 |issue = 4 |pages = 578–583 |url = http://www.maik.rssi.ru/cgi-perl/search.pl?type=abstract&name=inrgchem&number=4&year=2&page=578 |url-status = dead |archive-url = https://web.archive.org/web/20151222111809/http://www.maik.rssi.ru/cgi-perl/search.pl?type=abstract&name=inrgchem&number=4&year=2&page=578 |archive-date = 2015-12-22 }}</ref>

Two polymorphs of [[technetium trichloride]] exist, α- and β-TcCl₃. The α polymorph is also denoted as Tc₃Cl₉. It adopts a confacial [[Octahedral molecular geometry#Bioctahedral molecular geometry|bioctahedral structure]].<ref>{{cite journal|doi=10.1021/ja105730e|pmid=20977207|title=Synthesis and Structure of Technetium Trichloride|journal=Journal of the American Chemical Society|volume=132|issue=45|pages=15864–5|year=2010|last1=Poineau|first1=Frederic|last2=Johnstone|first2=Erik V.|last3=Weck|first3=Philippe F.|last4=Kim|first4=Eunja|last5=Forster|first5=Paul M.|last6=Scott|first6=Brian L.|last7=Sattelberger|first7=Alfred P.|last8=Czerwinski|first8=Kenneth R.}}</ref> It is prepared by treating the chloro-acetate Tc₂(O₂CCH₃)₄Cl₂ with HCl. Like [[Trirhenium nonachloride|Re₃Cl₉]], the structure of the α-polymorph consists of triangles with short M-M distances. β-TcCl₃ features octahedral Tc centers, which are organized in pairs, as seen also for [[molybdenum trichloride]]. TcBr₃ does not adopt the structure of either trichloride phase. Instead it has the structure of [[molybdenum tribromide]], consisting of chains of confacial octahedra with alternating short and long Tc—Tc contacts. TcI₃ has the same structure as the high temperature phase of [[titanium(III) iodide|TiI₃]], featuring chains of confacial octahedra with equal Tc—Tc contacts.<ref name="AS" />

Several anionic technetium halides are known. The binary tetrahalides can be converted to the hexahalides [TcX₆]²⁻ (X = F, Cl, Br, I), which adopt [[octahedral molecular geometry]].<ref name="s8" /> More reduced halides form anionic clusters with Tc–Tc bonds. The situation is similar for the related elements of Mo, W, Re. These clusters have the nuclearity Tc₄, Tc₆, Tc₈, and Tc₁₃. The more stable Tc₆ and Tc₈ clusters have prism shapes where vertical pairs of Tc atoms are connected by triple bonds and the planar atoms by single bonds. Every technetium atom makes six bonds, and the remaining valence electrons can be saturated by one axial and two [[bridging ligand]] halogen atoms such as [[chlorine]] or [[bromine]].<ref>{{cite journal|first1 = K. E.|last1 = German|last2 = Kryutchkov|first2 = S. V.|title = Polynuclear Technetium Halide Clusters|journal = Russian Journal of Inorganic Chemistry|volume = 47|issue = 4|date = 2002|pages = 578–583|url = http://www.maik.rssi.ru/cgi-perl/search.pl?type=abstract&name=inrgchem&number=4&year=2&page=578|archive-url = https://web.archive.org/web/20151222111809/http://www.maik.rssi.ru/cgi-perl/search.pl?type=abstract&name=inrgchem&number=4&year=2&page=578|url-status = dead|archive-date = 2015-12-22}}</ref>

===Coordination and organometallic complexes===

[[File:Tc CNCH2CMe2(OMe) 6Cation.png|thumb|right|[[Technetium (99mTc) sestamibi|Technetium (^99mTc) sestamibi]] ("Cardiolite") is widely used for imaging of the heart.]]

Technetium forms a variety of [[coordination complex]]es with organic ligands. Many have been well-investigated because of their relevance to [[nuclear medicine]].<ref>{{cite journal |doilast1=10Bartholomä |first1=Mark D.1021/cr1000755 |pmidlast2=20415476Louie |first2=Anika S. |last3=Valliant |first3=John F. |last4=Zubieta |first4=Jon |year=2010 |title=Technetium and Galliumgallium Derivedderived Radiopharmaceuticalsradiopharmaceuticals: Comparing and Contrastingcontrasting the Chemistrychemistry of Twotwo Importantimportant Radiometalsradiometals for the Molecularmolecular Imagingimaging era Era|journal=Chemical Reviews |volume=110 |issue=5 |pages=2903–20|year=2010|last1=Bartholomä|first1=Mark D.|last2doi=Louie|first2=Anika S10.|last3=Valliant|first3=John1021/cr1000755 F.|last4pmid=Zubieta|first4=Jon20415476 }}</ref>

Technetium forms a variety of compounds with Tc–C bonds, i.e. organotechnetium complexes. Prominent members of this class are complexes with CO, arene, and cyclopentadienyl ligands.<ref name="Alberto" /> The binary carbonyl Tc₂(CO)₁₀ is a white volatile solid.<ref>{{cite journal|doi = 10.1021/ja01474a038|date = 1961|last1 = Hileman |first1 = J. C. |last2 = Huggins |first2 = D.K. |last3 = Kaesz |first3 = H.D. |date = 1961 |title = Technetium carbonyl |journal = Journal of the American Chemical Society |volume = 83 |titleissue = Technetium13 carbonyl|pages = 2953–2954|first2 = D. K.|first3doi = H10. D.|issue = 131021/ja01474a038}}</ref> In this molecule, two technetium atoms are bound to each other; each atom is surrounded by [[octahedron|octahedra]] of five carbonyl ligands. The bond length between technetium atoms, 303&nbsp;pm,<ref>{{cite journal |titlelast1 =Bailey The|first1 Crystal= StructureM.F. of|last2 Ditechnetium= Dahl Decacarbonyl|doifirst2 =10 Lawrence F.1021/ic50030a011 |date =1965|last1 =Bailey|first1title = M.The crystal structure of ditechnetium decacarbonyl F.|journal =Inorganic Chemistry |volume =4|pages =1140–1145|last2issue = Dahl8 |first2pages =1140–1145 Lawrence F.|issuedoi =10.1021/ic50030a011 8}}</ref><ref>{{cite journal |doilast1 = 10Wallach |first1 = D.1107/S0365110X62002789 |date = 1962 |title = Unit cell and space group of technetium carbonyl, Tc2(CO)10|date = 1962|last1 = Wallach|first1 = D.|journal = Acta Crystallographica |volume = 15 |pageissue = 105810 |issuepage = 101058 | bibcode=1962AcCry..15.1058W |doi = 10.1107/S0365110X62002789 }}</ref> is significantly larger than the distance between two atoms in metallic technetium (272&nbsp;pm). Similar [[carbonyl]]s are formed by technetium's [[Congener (chemistry)|congeners]], manganese and rhenium.{{sfn|Schwochau|2000|pp=286, 328}} Interest in organotechnetium compounds has also been motivated by applications in [[nuclear medicine]].<ref name="Alberto">{{cite book |doilast1=10.1007/978-3-642-13185-1_9Alberto |first1=Roger |year=2010 |chapter=Organometallic Radiopharmaceuticalsradiopharmaceuticals |title=Medicinal Organometallic Chemistry |volume=32 |pages=219–246 |series=Topics in Organometallic Chemistry|year=2010 |last1=Alberto|first1=Roger|isbn=978-3-642-13184-4 |doi=10.1007/978-3-642-13185-1_9 }}</ref> Technetium also forms aquo-carbonyl complexes, one prominent complex being [Tc(CO)₃(H₂O)₃]⁺, which are unusual compared to other metal carbonyls.<ref name="Alberto" />

==Isotopes==

{{main|Isotopes of technetium}}

Technetium, with [[atomic number]] ''Z''&nbsp;= 43, is the lowest-numbered element in the periodic table for which all isotopes are [[radioactive]]. The second-lightest exclusively radioactive element, [[promethium]], has atomic number 61.<ref name="LANL" /> [[Atomic nucleus|Atomic nuclei]] with an odd number of [[proton]]s are less stable than those with even numbers, even when the total number of [[nucleon]]s (protons + [[neutron]]s) is even,<ref>{{cite book |urllast=https://archive.org/details/principlesofstel0000clayClayton |url-accessfirst=registrationD.D. |pagedate=[https://archive.org/details/principlesofstel0000clay/page/547 547]1983 |title=Principles of stellar evolution and nucleosynthesis: with a new preface |author=Clayton, D. D. |publisher=University of Chicago Press |date=1983 |isbn=978-0-226-10953-4 |url=https://archive.org/details/principlesofstel0000clay |url-access=registration |page=[https://archive.org/details/principlesofstel0000clay/page/547 547] }}</ref> and odd numbered elements have fewer stable [[isotope]]s.

The most stable [[Radionuclide|radioactive isotopes]] are technetium-97 with a [[half-life]] of {{val|4.21|0.16}}&nbsp;million&nbsp;years, and technetium-98 with {{val|4.2|0.3}}&nbsp;million&nbsp;years,; current measurements of their half-lives give overlapping [[confidence interval]]s corresponding to one [[standard deviation]] and therefore do not allow a definite assignment of technetium's most stable isotope. The next most stable isotope is technetium-99, withwhich has a half-life of 211,100&nbsp;years.{{NUBASE2016NUBASE2020|ref}} Thirty-four other radioisotopes have been characterized with [[mass number]]s ranging from 8586 to 118122.{{NUBASE2020|ref}} Most of these have half-lives that are less than an hour, the exceptions being technetium-93 (2.73&nbsp;hours), technetium-94 (4.88&nbsp;hours), technetium-95 (20&nbsp;hours), and technetium-96 (4.3&nbsp;days).<ref name="NNDC"CRCisotopes/>{{cite web

|editor = Sonzogni, A. A. |title = Chart of Nuclides

|url = http://www.nndc.bnl.gov/chart/

|access-date = 2009-11-11

|url-status = dead

|archive-url = https://web.archive.org/web/20090825001001/http://www.nndc.bnl.gov/chart/

|archive-date = 2009-08-25

|publisher = National Nuclear Data Center, Brookhaven National Laboratory

|location = New York}}</ref> Most of these have half-lives that are less than an hour, the exceptions being technetium-93 (2.73&nbsp;hours), technetium-94 (4.88&nbsp;hours), technetium-95 (20&nbsp;hours), and technetium-96 (4.3&nbsp;days).<ref name="CRCisotopes" />

The primary [[decay mode]] for isotopes lighter than technetium-98 (⁹⁸Tc) is [[electron capture]], producing [[molybdenum]] (''Z''&nbsp;=&nbsp;42).<ref name="NNDC" /> For technetium-98 and heavier isotopes, the primary mode is [[Beta decay|beta emission]] (the emission of an [[electron]] or [[positron]]), producing [[ruthenium]] (''Z''&nbsp;=&nbsp;44), with the exception that technetium-100 can decay both by beta emission and electron capture.<ref name="NNDC" /><ref>
{{cite book web
|titleeditor-last = The CRC Handbook of Chemistry and PhysicsSonzogni |publisher editor-first=CRC press A.A.
|chaptertitle = TableChart of the isotopes nuclides
|dateseries = 2004–2005National |editorNuclear =Data Lide, David R.}}</ref>Center

|publisher = [[Brookhaven National Laboratory]]

|place = Brookhaven, NY

|url = http://www.nndc.bnl.gov/chart/

|access-date = 2009-11-11 |url-status = dead

|archive-url = https://web.archive.org/web/20090825001001/http://www.nndc.bnl.gov/chart/

|archive-date = 2009-08-25

}}

</ref><ref>

{{cite book

|editor-last = Lide |editor-first=David R.

|date = 2004–2005

|section = Table of the isotopes

|title = The CRC Handbook of Chemistry and Physics

|place = Boca Raton, FL

|publisher =CRC press

}}

</ref>

Technetium also has numerous [[nuclear isomer]]s, which are isotopes with one or more [[Excited state|excited]] nucleons. Technetium-97m (^97mTc; "m" stands for [[metastability]]) is the most stable, with a half-life of 91&nbsp;days and [[excited state|excitation energy]] 0.0965&nbsp;MeV.<ref name="CRCisotopes">
{{cite book

|last = Holden |first = N.E.

|date = 2006

|first=N. E.

|title = Handbook of Chemistry and Physics |edition = 87th

|editor-last = Lide. |editor-first = D. R.

|publisher = CRC Press

|edition = 87th

|location = Boca Raton, FL

|date = 2006

|pages = 11‑88 – 11‑89

|publisher = CRC Press

|isbn = 978-0-8493-0487-3

|location = Boca Raton, Florida

}}

|pages = 11{{hyphen}}88{{ndash}}11{{hyphen}}89

</ref>

|isbn = 978-0-8493-0487-3}}</ref> This is followed by technetium-95m (61&nbsp;days, 0.03&nbsp;MeV), and technetium-99m (6.01&nbsp;hours, 0.142&nbsp;MeV).<ref name="CRCisotopes" /> Technetium-99m emits only [[gamma ray]]s and decays to technetium-99.<ref name="CRCisotopes" />

This is followed by technetium-95m (61&nbsp;days, 0.03&nbsp;MeV), and technetium-99m (6.01&nbsp;hours, 0.142&nbsp;MeV).<ref name="CRCisotopes" />

Technetium-99 (⁹⁹Tc) is a major product of the fission of uranium-235 (²³⁵U), making it the most common and most readily available isotope of technetium. One gram of technetium-99 produces {{nobr|6.2×10^{2 × {{10^|8}&nbsp;}} disintegrations}} per second (in other words, the [[specific activity]] of ⁹⁹Tc is 0.62&nbsp;G[[Becquerel|Bq]]/g).<ref name="enc" />

==Occurrence and production==

Technetium occurs naturally in the Earth's [[Crust (geology)|crust]] in minute concentrations of about 0.003 parts per trillion. Technetium is so rare because the [[half-life|half-lives]] of ⁹⁷Tc and ⁹⁸Tc are only {{nobr|4.2&nbsp; million&nbsp; years.}} More than a thousand of such periods have passed since the formation of the [[Earth]], so the probability of survival of even one atom of [[primordial nuclide|primordial]] technetium is effectively zero. However, small amounts exist as spontaneous [[fission product]]s in [[uranium ore]]s. A kilogram of uranium contains an estimated 1&nbsp;[[Orders of magnitude (mass)|nanogram]] {{nobr|({{10^{^|−9}&nbsp;}} g)}} equivalent to ten trillion atoms of technetium.<ref name="blocks" /><ref>{{cite journal|doi=10.1021/ac961159q |title=Analysis of Naturally Produced Technetium and Plutonium in Geologic Materials|date=1997 |last1=Dixon|first1=P.|last2=Curtis|first2=David B. |last3=Musgrave|first3=John |last4=Roensch|first4=Fred|last5=Roach|first5=Jeff|last6=Rokop|first6=Don|journal=Analytical Chemistry |volume=69|issue=9|pages=1692–1699|pmid=21639292}}</ref><ref>{{cite journal |doi=10.1016/S0016-7037(98)00282-8 |title=Nature's uncommon elements: plutonium and technetium|last1=Curtis|first1=D. |last2=Fabryka-Martin|first2=June|last3=Dixon|first3=Paul|last4=Cramer|first4=Jan|date=1999 |journal=Geochimica et Cosmochimica Acta |volume=63|issue=2|pages=275|bibcode=1999GeCoA..63..275C |url=https://digital.library.unt.edu/ark:/67531/metadc704244/}}</ref> Some [[red giant]] stars with the spectral types S-, M-, and N contain a spectral absorption line indicating the presence of technetium.{{sfn|Hammond|2004|p={{page needed|date=June 2021}}}}<ref>{{cite journal|doi=10.1126/science.114.2951.59|date=1951 |last1=Moore|first1=C. E.|title=Technetium in the Sun|journal=Science |volume=114 |issue=2951 |pages=59–61 |pmid=17782983|bibcode=1951Sci...114...59M}}</ref><!--Technetium in Red Giant Stars P Merrill&nbsp;— Science, 1952--> These red giants are known informally as [[technetium star]]s.

{{cite journal

|last1=Dixon |first1=P. |last2=Curtis |first2=David B.

|last3=Musgrave |first3=John |last4=Roensch |first4=Fred

|last5=Roach |first5=Jeff |last6=Rokop |first6=Don

|date=1997

|title=Analysis of naturally produced technetium and plutonium in geologic materials

|journal=Analytical Chemistry

|volume=69 |issue=9 |pages=1692–1699

|doi=10.1021/ac961159q |pmid=21639292

}}

</ref><ref>

{{cite journal

|last1=Curtis |first1=D. |last2=Fabryka-Martin |first2=June

|last3=Dixon |first3=Paul |last4=Cramer |first4=Jan

|date=1999

|title=Nature's uncommon elements: Plutonium and technetium

|journal=Geochimica et Cosmochimica Acta

|volume=63 |issue=2 |page=275

|bibcode=1999GeCoA..63..275C

|doi=10.1016/S0016-7037(98)00282-8

|url=https://digital.library.unt.edu/ark:/67531/metadc704244/

}}

</ref>

Some [[red giant]] stars with the spectral types S-, M-, and N display a spectral absorption line indicating the presence of technetium.{{sfn|Hammond|2004|p={{page needed|date=June 2021}}}}<ref>{{cite journal|doi=10.1126/science.114.2951.59|date=1951 |last1=Moore|first1=C. E.|title=Technetium in the Sun|journal=Science |volume=114 |issue=2951 |pages=59–61 |pmid=17782983|bibcode=1951Sci...114...59M}}</ref><!--Technetium in Red Giant Stars P Merrill&nbsp;— Science, 1952--> These red giants are known informally as [[technetium star]]s.

===Fission waste product===

In contrast to the rare natural occurrence, bulk quantities of technetium-99 are produced each year from [[spent nuclear fuel|spent nuclear fuel rods]], which contain various fission products. The fission of a gram of [[uranium-235]] in [[nuclear reactor]]s yields 27&nbsp;mg of technetium-99, giving technetium a [[fission product yield]] of 6.1%.<ref name="enc" /> Other [[fissile]] isotopes produce similar yields of technetium, such as 4.9% from [[uranium-233]] and 6.21% from [[plutonium-239]].{{sfn|Schwochau|2000|pp=374–404}} An estimated 49,000&nbsp;T[[Becquerel|Bq]] (78&nbsp;[[tonne|metric tons]]) of technetium was produced in nuclear reactors between 1983 and 1994, by far the dominant source of terrestrial technetium.<ref name="yoshihara">{{cite book| first=K.|last=Yoshihara| chapter=Technetium in the Environment| series=Topics in Current Chemistry| title=Technetium and Rhenium: Their Chemistry and Its Applications| volume=176 |editor=Yoshihara, K. |editor2=Omori, T. | publisher=Springer-Verlag| location=Berlin, Heidelberg| date=1996| isbn=978-3-540-59469-7|doi=10.1007/3-540-59469-8_2|pages=17–35}}</ref><ref name="leon" /> Only a fraction of the production is used commercially.{{efn|{{As of|2005}}, technetium-99 in the form of [[ammonium pertechnetate]] is available to holders of an [[Oak Ridge National Laboratory]] permit.{{sfn|Hammond|2004|p={{page needed|date=June 2021}}}} }}

{{cite book

|last=Yoshihara |first=K.

|date=1996

|chapter=Technetium in the environment

|editor1-last=Yoshihara |editor1-first=K.

|editor2-last=Omori |editor2-first=T.

|title=Technetium and Rhenium: Their chemistry and its applications

|series=Topics in Current Chemistry |volume=176

|publisher=Springer-Verlag

|location=Berlin / Heidelberg, DE

|isbn=978-3-540-59469-7

|doi=10.1007/3-540-59469-8_2

|pages=17–35

}}

</ref><ref name=leon/>

Only a fraction of the production is used commercially.{{efn|

{{As of|2005}}, technetium-99 in the form of [[ammonium pertechnetate]] is available to holders of an [[Oak Ridge National Laboratory]] permit.{{sfn|Hammond|2004|p={{page needed|date=June 2021}}}}

}}

Technetium-99 is produced by the [[nuclear fission]] of both uranium-235 and plutonium-239. It is therefore present in [[radioactive waste]] and in the [[nuclear fallout]] of [[nuclear weapon|fission bomb]] explosions. Its decay, measured in [[becquerel]]s per amount of spent fuel, is the dominant contributor to nuclear waste radioactivity after about {{nobr|{{10^|4}}~{{10^|6}} years}} after the creation of the nuclear waste.<ref name=yoshihara/> From 1945–1994, an estimated 160&nbsp;T[[Becquerel|Bq]] (about 250&nbsp;kg) of technetium-99 was released into the environment during atmospheric [[nuclear test]]s.<ref name=yoshihara/><ref>

Technetium-99 is produced by the [[nuclear fission]] of both uranium-235 and plutonium-239. It is therefore present in [[radioactive waste]] and in the [[nuclear fallout]] of [[nuclear weapon|fission bomb]] explosions. Its decay, measured in [[becquerel]]s per amount of spent fuel, is the dominant contributor to nuclear waste radioactivity after about 10⁴ to 10⁶&nbsp;years after the creation of the nuclear waste.<ref name="yoshihara" /> From 1945 to 1994, an estimated 160&nbsp;T[[Becquerel|Bq]] (about 250&nbsp;kg) of technetium-99 was released into the environment during atmospheric [[nuclear test]]s.<ref name="yoshihara" /><ref>{{cite book |url=https://books.google.com/books?id=QLHr-UYWoo8C&pg=PA69|page=69 |title=Technetium in the environment|last1=Desmet|first1=G. |last2=Myttenaere|first2=C. |publisher=Springer |date=1986|isbn=978-0-85334-421-6}}</ref> The amount of technetium-99 from nuclear reactors released into the environment up to 1986 is on the order of 1000&nbsp;TBq (about 1600&nbsp;kg), primarily by [[nuclear fuel reprocessing]]; most of this was discharged into the sea. Reprocessing methods have reduced emissions since then, but as of 2005 the primary release of technetium-99 into the environment is by the [[Sellafield]] plant, which released an estimated 550&nbsp;TBq (about 900&nbsp;kg) from 1995 to 1999 into the [[Irish Sea]].<ref name="leon">{{cite journal|journal=Journal of Nuclear and Radiochemical Sciences |volume=6|issue=3|pages=253–259|date=2005|url=http://www.radiochem.org/paper/JN63/jn6326.pdf |title=99Tc in the Environment: Sources, Distribution and Methods|last=Garcia-Leon|first=M.|doi=10.14494/jnrs2000.6.3_253 |doi-access=free}}</ref> From 2000 onwards the amount has been limited by regulation to 90&nbsp;TBq (about 140&nbsp;kg) per year.<ref>{{cite journal |title=Technetium-99 Behaviour in the Terrestrial Environment&nbsp;— Field Observations and Radiotracer Experiments |first=K. |last=Tagami |journal=Journal of Nuclear and Radiochemical Sciences |volume=4 |pages=A1–A8 |date=2003 |doi=10.14494/jnrs2000.4.a1 |doi-access=free |url=https://www.jstage.jst.go.jp/article/jnrs2000/4/1/4_1_A1/_pdf}}</ref> Discharge of technetium into the sea resulted in contamination of some seafood with minuscule quantities of this element. For example, [[European lobster]] and fish from west [[Cumbria]] contain about 1&nbsp;Bq/kg of technetium.<ref>{{cite book|url=https://books.google.com/books?id=zVmdln2pJxUC&pg=PA403 |page=403 |title=Mineral components in foods|last1=Szefer|first1=P.|last2=Nriagu|first2=J. O.|publisher=CRC Press |date=2006|isbn=978-0-8493-2234-1}}</ref><ref>{{cite journal| title=Gut transfer and doses from environmental technetium |first1=J. D.|last1=Harrison|first2=A.|last2=Phipps|date=2001|journal=J. Radiol. Prot.|pages=9–11|volume=21|issue=1 |doi=10.1088/0952-4746/21/1/004 |bibcode=2001JRP....21....9H |pmid=11281541|s2cid=250752077 }}</ref>{{efn|The [[anaerobic organism|anaerobic]], [[endospore|spore]]-forming [[bacteria]] in the ''[[Clostridium]]'' [[genus]] are able to reduce Tc(VII) to Tc(IV). ''Clostridia'' bacteria play a role in reducing iron, [[manganese]], and uranium, thereby affecting these elements' solubility in soil and sediments. Their ability to reduce technetium may determine a large part of mobility of technetium in industrial wastes and other subsurface environments.<ref>{{cite journal| last1=Francis |first1=A. J. |last2=Dodge |first2=C. J. |last3=Meinken |first3=G. E. |title=Biotransformation of pertechnetate by ''Clostridia'' |journal=Radiochimica Acta|volume=90|issue=9–11|date=2002|pages=791–797|doi= 10.1524/ract.2002.90.9-11_2002.791|s2cid=83759112 |url=https://zenodo.org/record/1236279}}</ref>}}

{{cite book

|last1=Desmet |first1=G.

|last2=Myttenaere |first2=C.

|date=1986

|title=Technetium in the Environment

|publisher=Springer

|isbn=978-0-85334-421-6

|page=69

|url=https://books.google.com/books?id=QLHr-UYWoo8C&pg=PA69

}}

</ref>

The amount of technetium-99 from nuclear reactors released into the environment up to 1986 is on the order of 1000&nbsp;TBq (about 1600&nbsp;kg), primarily by [[nuclear fuel reprocessing]]; most of this was discharged into the sea. Reprocessing methods have reduced emissions since then, but as of 2005 the primary release of technetium-99 into the environment is by the [[Sellafield]] plant, which released an estimated 550&nbsp;TBq (about 900&nbsp;kg) from 1995 to 1999 into the [[Irish Sea]].<ref name=leon>

{{cite journal

|last=Garcia-Leon |first=M.

|date=2005

|title={{sup|99}}Tc in the environment: Sources, distribution, and methods

|journal=Journal of Nuclear and Radiochemical Sciences

|volume=6 |issue=3 |pages=253–259

|doi=10.14494/jnrs2000.6.3_253 |doi-access=free

|url=http://www.radiochem.org/paper/JN63/jn6326.pdf

}}

</ref>

From 2000 onwards the amount has been limited by regulation to 90&nbsp;TBq (about 140&nbsp;kg) per year.<ref>

{{cite journal

|first=K. |last=Tagami

|date=2000

|title=Technetium-99 behaviour in the terrestrial environment — field observations and radiotracer experiments

|journal=Journal of Nuclear and Radiochemical Sciences

|volume=4 |pages=A1–A8

|doi=10.14494/jnrs2000.4.a1 |doi-access=free

|url=https://www.jstage.jst.go.jp/article/jnrs2000/4/1/4_1_A1/_pdf

}}

</ref>

Discharge of technetium into the sea resulted in contamination of some seafood with minuscule quantities of this element. For example, [[European lobster]] and fish from west [[Cumbria]] contain about 1&nbsp;Bq/kg of technetium.<ref>

{{cite book

|url=https://books.google.com/books?id=zVmdln2pJxUC&pg=PA403

|page=403

|title=Mineral Components in Foods

|last1=Szefer |first1=P.

|last2=Nriagu |first2=J.O.

|publisher=CRC Press

|date=2006

|isbn=978-0-8493-2234-1

}}

</ref><ref>

{{cite journal

|first1=J.D. |last1=Harrison

|first2=A. |last2=Phipps

|date=2001

|title=Gut transfer and doses from environmental technetium

|journal=Journal of Radiological Protection

|volume=21 |issue=1 |pages=9–11

|doi=10.1088/0952-4746/21/1/004

|bibcode=2001JRP....21....9H

|pmid=11281541 |s2cid=250752077

}}

</ref>{{efn|

The [[anaerobic organism|anaerobic]], [[endospore|spore]]-forming [[bacteria]] in the ''[[Clostridium]]'' [[genus]] are able to reduce Tc(VII) to Tc(IV). ''Clostridia'' bacteria play a role in reducing iron, [[manganese]], and uranium, thereby affecting these elements' solubility in soil and sediments. Their ability to reduce technetium may determine a large part of mobility of technetium in industrial wastes and other subsurface environments.<ref>

{{cite journal

|last1=Francis |first1=A.J.

|last2=Dodge |first2=C.J.

|last3=Meinken |first3=G.E.

|date=2002

|title=Biotransformation of pertechnetate by ''Clostridia''

|journal=Radiochimica Acta

|volume=90 |issue=9–11 |pages=791–797

|doi= 10.1524/ract.2002.90.9-11_2002.791

|s2cid=83759112

|url=https://zenodo.org/record/1236279

}}

</ref>

}}

===Fission product for commercial use===

The [[Metastability|metastable]] isotope technetium-99m is continuously produced as a [[fission product]] from the fission of uranium or [[plutonium]] in [[nuclear reactor]]s:

:<chem> ^{238}_{92}U ->[\ce{sf}] ^{137}_{53}I + ^{99}_{39}Y + 2^{1}_{0}n</chem>

:<chem display="block"> ^{238}_{92}U ->[\ce{sf}] ^{137}_{53}I + ^{99}_{39}Y + 2^{1}_{0}n</chem>
<chem display="block"> ^{99}_{39}Y ->[\beta^-][1.47\,\ce{s}] ^{99}_{40}Zr ->[\beta^-][2.1\,\ce{s}] ^{99}_{41}Nb ->[\beta^-][15.0\,\ce{s}] ^{99}_{42}Mo ->[\beta^-][65.94\,\ce{h}] ^{99}_{43}Tc ->[\beta^-][211,100\,\ce{y}] ^{99}_{44}Ru</chem>

Because used fuel is allowed to stand for several years before reprocessing, all molybdenum-99 and technetium-99m is decayed by the time that the fission products are separated from the major [[actinide]]s in conventional [[nuclear reprocessing]]. The liquid left after plutonium–uranium extraction ([[PUREX]]) contains a high concentration of technetium as {{chem|TcO|4|-}} but almost all of this is technetium-99, not technetium-99m.{{sfn|Schwochau|2000|p=39}}

Line 176 ⟶ 341:

===Waste disposal===

The long half-life of technetium-99 and its potential to form [[anionic]] species creates a major concern for long-term [[High-level radioactive waste management|disposal of radioactive waste]]. Many of the processes designed to remove fission products in reprocessing plants aim at [[cationic]] species such as [[caesium]] (e.g., [[caesium-137]]) and [[strontium]] (e.g., [[strontium-90]]). Hence the pertechnetate escapes through those processes. Current disposal options favor [[geological repository|burial]] in continental, geologically stable rock. The primary danger with such practice is the likelihood that the waste will contact water, which could leach radioactive contamination into the environment. The anionic pertechnetate and [[iodide]] tend not to adsorb into the surfaces of minerals, and are likely to be washed away. By comparison [[plutonium]], [[uranium]], and [[caesium]] tend to bind to soil particles. Technetium could be immobilized by some environments, such as microbial activity in lake bottom sediments,<ref>{{cite journal | last1 = German | first1 = Konstantin E. | last2 = Firsova | first2 = E. V. | title = Bioaccumulation of Tc, Pu, and Np on Bottom Sediments in Two Types of Freshwater Lakes of the Moscow Oblast | journal = Radiochemistry | volume = 45 | pages = 250–6250–256 | date = 2003 | issue = 6 | doi = 10.1023/A:1026008108860 | last3 = Peretrukhin | first3 = V. F. | last4 = Khizhnyak | first4 = T. V. | last5 = Simonoff | first5 = M. | bibcode = 2003Radch..45..250G | s2cid = 55030255 }}</ref> and the [[environmental chemistry]] of technetium is an area of active research.<ref>{{cite book|url=https://books.google.com/books?id=eEeJbur_je0C&pg=PA147|page=147|title=Radioactivity in the terrestrial environment|last=Shaw |first=G. |publisher=Elsevier |date=2007 |isbn=978-0-08-043872-6}}</ref>

An alternative disposal method, [[Nuclear transmutation|transmutation]], has been demonstrated at [[CERN]] for technetium-99. In this process, the technetium (technetium-99 as a metal target) is bombarded with [[neutron]]s to form the short-lived technetium-100 (half-life = 16&nbsp;seconds) which decays by beta decay to stable [[ruthenium]]-100. If recovery of usable ruthenium is a goal, an extremely pure technetium target is needed; if small traces of the [[minor actinide]]s such as [[americium]] and [[curium]] are present in the target, they are likely to undergo fission and form more [[fission product]]s which increase the radioactivity of the irradiated target. The formation of ruthenium-106 (half-life 374&nbsp;days) from the 'fresh fission' is likely to increase the activity of the final ruthenium metal, which will then require a longer cooling time after irradiation before the ruthenium can be used.<ref>{{cite book|url=http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=2000XT88.txt|title=Alternative disposal concepts for high-level and transuranic radioactive waste disposal|publisher=US Environmental Protection Agency|date=1979|author=Altomare, P|last2=Bernardi}}</ref>

Line 186 ⟶ 351:

===Particle accelerators===

The feasibility of technetium-99m production with the 22-MeV-proton bombardment of a molybdenum-100 target in medical cyclotrons following the reaction ¹⁰⁰Mo(p,2n)^99mTc was demonstrated in 1971.<ref>{{cite journal|last1=Beaver|first1=J. E.|author2last2=Hupf, |first2=H. B. |title=Production of ^99mTc on a Medical Cyclotron: a Feasibility Study|journal=Journal of Nuclear Medicine|date=November 1971 |volume=12|issue=11|pages=739–741 |pmid=5113635|url=http://jnm.snmjournals.org/content/12/11/739.full.pdf}}</ref> The recent shortages of medical technetium-99m reignited the interest in its production by proton bombardment of isotopically enriched (>99.5%) molybdenum-100 targets.<ref name="bbc-20150530">{{cite news |url=https://www.bbc.co.uk/news/magazine-32833599 |title=The element that can make bones glow |author=Laurence Knight |publisherwork=BBC News |date=30 May 2015 |access-date=30 May 2015}}</ref><ref>{{cite journal|display-authors=4|author=Guérin B|author2=Tremblay S|author3=Rodrigue S|author4=Rousseau JA |author5=Dumulon-Perreault V|author6=Lecomte R|author7=van Lier JE|author8=Zyuzin A|author9=van Lier EJ |name-list-style=vanc |title=Cyclotron production of ^99mTc: an approach to the medical isotope crisis|journal=Journal of Nuclear Medicine |date=2010|volume=51|issue=4|pages=13N–6N|pmid=20351346 |url=http://jnm.snmjournals.org/content/51/4/13N.full.pdf}}</ref> Other techniques are being investigated for obtaining molybdenum-99 from molybdenum-100 via (n,2n) or (γ,n) reactions in particle accelerators.<ref>{{cite journal |last1=Scholten|first1=Bernhard|last2=Lambrecht|first2= Richard M.|last3=Cogneau |first3=Michel|last4= Vera Ruiz|first4=Hernan|last5=Qaim|first5=Syed M.|title=Excitation functions for the cyclotron production of ^99mTc and ⁹⁹Mo|journal=Applied Radiation and Isotopes|date=25 May 1999|volume=51|issue=1 |pages=69–80|doi=10.1016/S0969-8043(98)00153-5|bibcode=1999AppRI..51...69S }}</ref><ref>{{cite journal |last1=Takács|first1=S.|last2=Szűcs|first2=Z. |last3=Tárkányi |first3=F. |last4=Hermanne|first4=A. |last5=Sonck|first5=M.|title=Evaluation of proton induced reactions on ¹⁰⁰Mo: New cross sections for production of ^99mTc and ⁹⁹Mo |journal=Journal of Radioanalytical and Nuclear Chemistry|date=1 January 2003|volume=257|issue=1|pages=195–201|doi=10.1023/A:1024790520036|s2cid=93040978}}</ref><ref>{{cite journal|last1=Celler|first1=A.|last2=Hou|first2=X.|last3=Bénard|first3=F. |last4=Ruth |first4=T. |title=Theoretical modeling of yields for proton-induced reactions on natural and enriched molybdenum targets|journal=Physics in Medicine and Biology|date=2011|volume=56|issue=17|pages=5469–5484 |doi=10.1088/0031-9155/56/17/002|pmid=21813960|bibcode=2011PMB....56.5469C|s2cid=24231457 }}</ref>

==Applications==

Line 203 ⟶ 368:

Like [[rhenium]] and [[palladium]], technetium can serve as a [[catalyst]]. In processes such as the [[dehydrogenation]] of [[isopropyl alcohol]], it is a far more effective catalyst than either rhenium or palladium. However, its radioactivity is a major problem in safe catalytic applications.{{sfn|Schwochau|2000|pp=87–90}}

When steel is immersed in water, adding a small concentration (55&nbsp;[[parts per notation|ppm]]) of potassium pertechnetate(VII) to the water protects the [[steel]] from corrosion,<ref name=":0">{{Cite web |title=Technetium (Tc) {{!}} AMERICAN ELEMENTS ® |url=https://www.americanelements.com/tc.html |access-date=2024-05-24 |website=American Elements: The Materials Science Company |language=en}}</ref> even if the temperature is raised to {{convert|250|C|K|abbr=on}}.{{sfn|Emsley|2001|p=425}} For this reason, pertechnetate has been used as an anodic [[corrosion]] inhibitor for steel, although technetium's radioactivity poses problems that limit this application to self-contained systems.<ref>{{cite book|chapter=Ch. 14 Separation Techniques |date=July 2004 |title=EPA: 402-b-04-001b-14-final |publisher=US Environmental Protection Agency |chapter-url=https://www.epa.gov/sites/production/files/2015-05/documents/402-b-04-001b-14-final.pdf |archive-url=https://web.archive.org/web/20140308042639/http://www.epa.gov/radiation/docs/marlap/402-b-04-001b-14-final.pdf |archive-date=2014-03-08 |url-status=live |access-date=2008-08-04}}</ref> While (for example) {{chem|CrO|4|2-}} can also inhibit corrosion, it requires a concentration ten times as high. In one experiment, a specimen of carbon steel was kept in an aqueous solution of pertechnetate for 20&nbsp;years and was still uncorroded.{{sfn|Emsley|2001|p=425}} The mechanism by which pertechnetate prevents corrosion is not well understood, but seems to involve the reversible formation of a thin surface layer ([[Passivation (chemistry)|passivation]]). One theory holds that the pertechnetate reacts with the steel surface to form a layer of [[technetium dioxide]] which prevents further corrosion; the same effect explains how iron powder can be used to remove pertechnetate from water. The effect disappears rapidly if the concentration of pertechnetate falls below the minimum concentration or if too high a concentration of other ions is added.{{sfn|Schwochau|2000|p=91}}

As noted, the radioactive nature of technetium (3&nbsp;MBq/L at the concentrations required) makes this corrosion protection impractical in almost all situations.<ref name=":0" /> Nevertheless, corrosion protection by pertechnetate ions was proposed (but never adopted) for use in [[boiling water reactor]]s.{{sfn|Schwochau|2000|p=91}}

Line 216 ⟶ 381:

==References==

{{reflist|30em25em}}

== Bibliography ==

{{refbegin|30em25em|small=yes}}

* <!-- Em -->{{cite book

|title = Nature's Building Blocks: An A-Z Guide to the Elements

|last = Emsley |first = J.

|publisher = Oxford University Press

|first = J.

|year = 2001

|publisher = Oxford University Press

|location = Oxford, England, UK

|year = 2001

|isbn = 978-0-19-850340-8

|location = Oxford, England, UK

|url = https://books.google.com/books?id=j-Xu07p3cKwC

|isbn = 978-0-19-850340-8

|url = https://books.google.com/books?id=j-Xu07p3cKwC

}}

* <!-- Gr -->{{cite book

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* {{cite book

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* {{cite book

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* {{cite book |last=Hammond |first=C. R. |date=2004 |chapter=The Elements |title=Handbook of Chemistry and Physics |edition=81st |publisher=CRC press |isbn=978-0-8493-0485-9 |chapter-url=https://archive.org/details/crchandbookofche81lide}}

* {{cite book |title=A Tale of Seven Elements|first1= Eric|last1= Scerri|year=2013|publisher=Oxford University Press, ISBN 9780195391312 }}

* <!-- Sc -->{{cite book|url=https://books.google.com/books?id=BHjxH8q9iukC&pg=PP1|last=Schwochau |first=K. |year=2000 |title=Technetium: Chemistry and Radiopharmaceutical Applications |place=Weinheim, Germany |publisher=Wiley-VCH |isbn=978-3-527-29496-1}}

{{refend}}

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{{Commons|Technetium}}

{{refbegin|25em|small=yes}}

* {{cite book|chapter-url=https://books.google.com/books?id=0Pr7aMRxLZ8C&pg=RA1-PA41|chapter=Nuclear Mass and Stability|title=Radiochemistry and nuclear chemistry|first1=G.|last1=Choppin|first2=J.-O.|last2=Liljenzin|first3=J.|last3=Rydberg|edition=3rd|date=2002|isbn=978-0-7506-7463-8|pages=41–57|publisher=Butterworth-Heinemann|author2-link=Jan-Olov Liljenzin}}

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* {{cite book| last=Scerri| first=E. R.| year=2007| title=The Periodic Table, Its Story and Its Significance| url=https://archive.org/details/periodictableits0000scer| url-access=registration| publisher=Oxford University Press| isbn=978-0-19-530573-9}}

* {{cite book|editor-last=Wilson|editor-first=B.J. |year=1966|title=The Radiochemical Manual|publisher=AEA Technology |edition=2nd |isbn=978-0-7058-1768-4}}

* {{cite web

* [http://environmentalchemistry.com/yogi/periodic/Tc.html EnvironmentalChemistry.com&nbsp;– Technetium]<!--per the guidelines at [http://en.wikipedia.org/wiki/Wikipedia:WikiProject_Elements Wikipedia's WikiProject Elements] (all viewed 1 December 2002)-->

|title=Technetium

* [http://www.nndc.bnl.gov/nudat2/index.jsp Nudat 2] {{Webarchive|url=https://web.archive.org/web/20210428124450/http://www.nndc.bnl.gov/nudat2/index.jsp |date=2021-04-28 }} nuclide chart from the National Nuclear Data Center, Brookhaven National Laboratory

|website=EnvironmentalChemistry.com

|url=http://environmentalchemistry.com/yogi/periodic/Tc.html

|access-date=1 December 2002

}}

* {{cite report

|title = Nuclide chart

|series = National Nuclear Data Center

|place = Brookhaven, NY

|publisher = [[Brookhaven National Laboratory]]

|url = http://www.nndc.bnl.gov/nudat2/index.jsp

|archive-url = https://web.archive.org/web/20210428124450/http://www.nndc.bnl.gov/nudat2/index.jsp

|archive-date = 2021-04-28

}}

{{refend}}

==External links==

{{Wiktionary|technetium}}

* {{cite AV media

* [http://www.periodicvideos.com/videos/043.htm Technetium] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)

|title=Technetium

|series=[[The Periodic Table of Videos]]

|publisher=University of Nottingham

|place=Nottingham, UK

|medium=video

|url=http://www.periodicvideos.com/videos/043.htm

}}

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