Editing Technetium (section)

===Chemical properties===
Technetium is located in [[Group 7 element|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]] 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 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 ''not'' 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 |last=Husted |first=R. |date=2003-12-15 |title=Technetium |series=Periodic Table of the Elements |publisher=[[Los Alamos National Laboratory]] |place=Los 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 [[non-stoichiometric compound|non-stoichiometric]] hydride TcH{{sub|1.3}}<ref name="Zhou 2023">{{cite 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=Synthesis of technetium hydride TcH<sub>1.3</sub> at 27&nbsp;GPa |url=https://link.aps.org/doi/10.1103/PhysRevB.107.064102 |journal=Physical Review B |volume=107 |issue=6 |page=064102 |doi=10.1103/PhysRevB.107.064102 |arxiv=2210.01518 |bibcode=2023PhRvB.107f4102Z }}</ref> and while reacting with [[carbon]] it forms Tc{{sub|6}}C,<ref name=carbide>{{cite 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 carbide and new orthorhombic Tc metal phase |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 0.398&nbsp;nm.

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.