Editing Bohrium

{{distinguish|Borium|barium|boron}}
{{good article}}
{{infobox bohrium}}
'''Bohrium''' is a [[synthetic element|synthetic chemical element]]; it has [[Chemical symbol|symbol]] '''Bh''' and [[atomic number]] 107. It is named after Danish physicist [[Niels Bohr]]. As a synthetic element, it can be created in [[particle accelerator]]s but is not found in nature. All known [[isotopes of bohrium]] are highly [[Radioactive decay|radioactive]]; the most stable known [[isotope]] is <sup>270</sup>Bh with a [[half-life]] of approximately 2.4 minutes, though the unconfirmed <sup>278</sup>Bh may have a longer half-life of about 11.5 minutes.

In the [[periodic table]], it is a [[Block (periodic table)#d-block|d-block]] [[Superheavy element|transactinide element]]. It is a member of the [[Period 7 element|7th period]] and belongs to the [[group 7 element]]s as the fifth member of the 6d series of [[transition metal]]s. Chemistry experiments have confirmed that bohrium behaves as the heavier [[Homologous series|homologue]] to [[rhenium]] in group 7. The [[Chemical property|chemical properties]] of bohrium are characterized only partly, but they compare well with the chemistry of the other group 7 elements.

==Introduction==
{{Excerpt|Superheavy element|Introduction|subsections=yes}}

==History==
[[File:Niels Bohr.jpg|thumb|left|upright|Element 107 was originally proposed to be named after [[Niels Bohr]], a Danish nuclear/theoretical

physicist, with the name ''nielsbohrium'' (Ns). This name was later changed by [[IUPAC]] to ''bohrium'' (Bh).]]

===Discovery===
Two groups claimed [[Timeline of chemical element discoveries|discovery of the element]]. Evidence of bohrium was first reported in 1976 by a Soviet research team led by [[Yuri Oganessian]], in which targets of [[bismuth-209]] and [[lead-208]] were bombarded with accelerated nuclei of [[chromium-54]] and [[manganese-55]], respectively.<ref>{{cite journal|doi=10.1016/0375-9474(76)90607-2|title= On spontaneous fission of neutron-deficient isotopes of elements | volume=273|year=1976|journal=Nuclear Physics A|pages=505–522  | last1 = Yu | last2 = Demin | first2 = A. G. | last3 = Danilov | first3 = N. A. | last4 = Flerov | first4 = G. N. | last5 = Ivanov | first5 = M. P. | last6 = Iljinov | first6 = A. S. | last7 = Kolesnikov | first7 = N. N. | last8 = Markov | first8 = B. N. | last9 = Plotko | first9 = V. M. | last10 = Tretyakova | first10 = S. P.}}</ref> Two activities, one with a half-life of one to two milliseconds, and the other with an approximately five-second half-life, were seen. Since the ratio of the intensities of these two activities was constant throughout the experiment, it was proposed that the first was from the isotope [[bohrium-261]] and that the second was from its daughter [[dubnium-257]]. Later, the dubnium isotope was corrected to [[dubnium-258]], which indeed has a five-second half-life (dubnium-257 has a one-second half-life); however, the half-life observed for its parent is much shorter than the half-lives later observed in the definitive discovery of bohrium at [[Darmstadt]] in 1981. The [[International Union of Pure and Applied Chemistry|IUPAC]]/IUPAP Transfermium Working Group (TWG) concluded that while [[dubnium-258]] was probably seen in this experiment, the evidence for the production of its parent [[bohrium-262]] was not convincing enough.<ref name="93TWG" />

In 1981, a German research team led by [[Peter Armbruster]] and [[Gottfried Münzenberg]] at the [[GSI Helmholtz Centre for Heavy Ion Research]] (GSI Helmholtzzentrum für Schwerionenforschung) in Darmstadt bombarded a target of bismuth-209 with accelerated nuclei of chromium-54 to produce 5 atoms of the isotope bohrium-262:<ref name="262Bh">{{cite journal
|last1=Münzenberg
|first1=G.
|last2=Hofmann
|first2=S.
|last3=Heßberger
|first3=F. P.
|last4=Reisdorf
|first4=W.
|last5=Schmidt
|first5=K. H.
|last6=Schneider
|first6=J. H. R.
|last7=Armbruster
|first7=P.
|last8=Sahm
|first8=C. C.
|last9=Thuma
|first9=B.
|year=1981
|title=Identification of element 107 by α correlation chains
|journal=Zeitschrift für Physik A
|volume=300
|issue=1
|pages=107–8
|doi=10.1007/BF01412623
|bibcode = 1981ZPhyA.300..107M
|s2cid=118312056
|url=https://www.researchgate.net/publication/238901044
|access-date=24 December 2016
}}</ref>

:{{nuclide|link=yes|bismuth|209}} + {{nuclide|link=yes|chromium|54}} → {{nuclide|link=yes|bohrium|262}} + {{SubatomicParticle|link=yes|neutron}}

This discovery was further substantiated by their detailed measurements of the alpha decay chain of the produced bohrium atoms to previously known isotopes of [[fermium]] and [[californium]]. The [[International Union of Pure and Applied Chemistry|IUPAC]]/IUPAP Transfermium Working Group (TWG) recognised the GSI collaboration as official discoverers in their 1992 report.<ref name="93TWG">{{Cite journal
|doi=10.1351/pac199365081757
|title=Discovery of the transfermium elements. Part II: Introduction to discovery profiles. Part III: Discovery profiles of the transfermium elements
|year=1993
|author=Barber, R. C.
|journal=Pure and Applied Chemistry
|volume=65
|pages=1757
|last2=Greenwood
|first2=N. N.
|last3=Hrynkiewicz
|first3=A. Z.
|last4=Jeannin
|first4=Y. P.
|last5=Lefort
|first5=M.
|last6=Sakai
|first6=M.
|last7=Ulehla
|first7=I.
|last8=Wapstra
|first8=A. P.
|last9=Wilkinson
|first9=D. H.
|issue=8|s2cid=195819585
|doi-access=free
}}</ref>

===Proposed names===
<!-- Deleted image removed: [[File:Bohrium hassium meitnerium ceremony.jpg|thumb|left|Naming ceremony conducted at the GSI on 7 September 1992 for the namings of elements 107, 108, and 109 as nielsbohrium, hassium, and meitnerium]] -->
In September 1992, the German group suggested the name ''nielsbohrium'' with symbol ''Ns'' to honor the Danish physicist [[Niels Bohr]]. The Soviet scientists at the [[Joint Institute for Nuclear Research]] in [[Dubna]], Russia had suggested this name be given to element 105 (which was finally called dubnium) and the German team wished to recognise both Bohr and the fact that the Dubna team had been the first to propose the cold fusion reaction, and simultaneously help to solve the controversial problem of the naming of element 105. The Dubna team agreed with the German group's naming proposal for element 107.<ref>{{cite journal |doi =10.1351/pac199365081815
|title =Responses on 'Discovery of the transfermium elements' by Lawrence Berkeley Laboratory, California; Joint Institute for Nuclear Research, Dubna; and Gesellschaft fur Schwerionenforschung, Darmstadt followed by reply to responses by the Transfermium Working Group |year =1993
|last1= Ghiorso
|first1=A.
|last2=Seaborg |first2=G. T.
|last3=Organessian |first3=Yu. Ts.
|last4=Zvara |first4=I.
|last5=Armbruster |first5=P.
|last6=Hessberger |first6=F. P.
|last7=Hofmann |first7=S.
|last8=Leino |first8=M.
|last9=Munzenberg |first9=G.
|last10=Reisdorf |first10=W.
|last11=Schmidt |first11=K.-H.
|journal =Pure and Applied Chemistry
|volume =65
|issue = 8
|pages =1815–1824
|doi-access=free
}}</ref>

There was an [[element naming controversy]] as to what the elements from 104 to 106 were to be called; the [[IUPAC]] adopted ''unnilseptium'' (symbol ''Uns'') as a temporary, [[systematic element name]] for this element.<ref name="IUPAC97" /> In 1994 a committee of IUPAC recommended that element 107 be named ''bohrium'', not ''nielsbohrium'', since there was no precedent for using a scientist's complete name in the naming of an element.<ref name="IUPAC97" /><ref name="IUPAC94">{{Cite journal|doi=10.1351/pac199466122419|title=Names and symbols of transfermium elements (IUPAC Recommendations 1994)|date=1994|journal=Pure and Applied Chemistry|volume=66|pages=2419–2421|issue=12|doi-access=free}}</ref> This was opposed by the discoverers as there was some concern that the name might be confused with [[boron]] and in particular the distinguishing of the names of their respective [[oxyanion]]s, ''bohrate'' and ''borate''. The matter was handed to the Danish branch of IUPAC which, despite this, voted in favour of the name ''bohrium'', and thus the name ''bohrium'' for element 107 was recognized internationally in 1997;<ref name="IUPAC97" /> the names of the respective oxyanions of boron and bohrium remain unchanged despite their homophony.<ref>{{RedBook2005|pages=337–9}}</ref>

==Isotopes==
{{main|Isotopes of bohrium}}
{{clear}}
{{Isotopes summary
|element=bohrium
|isotopes=
{{isotopes summary/isotope
|mn=260|sym=Bh|hl={{sort|41|41 ms}}|ref={{NUBASE2020|ref}}
|dm=α |year=2007|re=<sup>209</sup>Bi(<sup>52</sup>Cr,n)<ref name="260Bh">{{cite journal|last1=Nelson|first1=S.|last2=Gregorich|first2=K.|last3=Dragojević|first3=I.|last4=Garcia|first4=M.|last5=Gates|first5=J.|last6=Sudowe|first6=R.|last7=Nitsche|first7=H.|title=Lightest Isotope of Bh Produced via the Bi209(Cr52,n)Bh260 Reaction|journal=Physical Review Letters|volume=100|date=2008|doi=10.1103/PhysRevLett.100.022501|issue=2|bibcode=2008PhRvL.100b2501N|pmid=18232860|page=022501|s2cid=1242390 |url=https://digital.library.unt.edu/ark:/67531/metadc895291/m2/1/high_res_d/923353.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://digital.library.unt.edu/ark:/67531/metadc895291/m2/1/high_res_d/923353.pdf |archive-date=2022-10-09 |url-status=live}}</ref>
}}
{{isotopes summary/isotope
|mn=261|sym=Bh|hl={{sort|12|12.8 ms}}|ref={{NUBASE2020|ref}}
|dm=α |year=1986|re=<sup>209</sup>Bi(<sup>54</sup>Cr,2n)<ref name="261Bh">{{cite journal|doi=10.1007/BF01565147|title=Element 107|date=1989|author=Münzenberg, G.|journal=Zeitschrift für Physik A|volume=333|pages=163
|last2=Armbruster|first2=P.|last3=Hofmann|first3=S.|last4=Heßberger|first4=F. P.|last5=Folger|first5=H.|last6=Keller|first6=J. G.|last7=Ninov|first7=V.|last8=Poppensieker|first8=K.|last9=Quint|first9=A. B.|display-authors=8
|issue=2|bibcode = 1989ZPhyA.333..163M |s2cid=186231905}}</ref>
}}
{{isotopes summary/isotope
|mn=262|sym=Bh|hl={{sort|84|84 ms}}|ref={{NUBASE2020|ref}}
|dm=α |year=1981|re=<sup>209</sup>Bi(<sup>54</sup>Cr,n)<ref name="262Bh" />
}}
{{isotopes summary/isotope
|mn=262m|sym=Bh|hl={{sort|9|9.5 ms}}|ref={{NUBASE2020|ref}}
|dm=α |year=1981|re=<sup>209</sup>Bi(<sup>54</sup>Cr,n)<ref name="262Bh" />
}}
{{isotopes summary/isotope
|mn=264|sym=Bh|hl={{sort|1070|1.07 s}}|ref={{NUBASE2020|ref}}
|dm=α |year=1994|re=<sup>272</sup>Rg(—,2α)<ref name="264Bh">{{cite journal
|doi=10.1007/BF01291182
|title=The new element 111
|year=1995
|author=Hofmann, S.
|journal=Zeitschrift für Physik A
|volume=350
|pages=281
|last2=Ninov
|first2=V.
|last3=Heßberger
|first3=F. P.
|last4=Armbruster
|first4=P.
|last5=Folger
|first5=H.
|last6=Münzenberg
|first6=G.
|last7=Schött
|first7=H. J.
|last8=Popeko
|first8=A. G.
|last9=Yeremin
|first9=A. V.
|first10=A. N.
|last10=Andreyev
|first11=S.
|last11=Saro
|first12=R.
|last12=Janik
|first13=M.
|last13=Leino
|bibcode = 1995ZPhyA.350..281H
|issue=4
|s2cid=18804192
}}</ref>
}}
{{isotopes summary/isotope
|mn=265|sym=Bh|hl={{sort|1190|1.19 s}}|ref={{NUBASE2020|ref}}
|dm=α |year=2004|re=<sup>243</sup>Am(<sup>26</sup>Mg,4n)<ref name="265Bh">{{cite journal|title=New isotope <sup>265</sup>Bh|doi=10.1140/epja/i2004-10020-2|date=2004|author=Gan, Z.G.|journal=The European Physical Journal A|volume=20|last2=Guo|first2=J. S.|last3=Wu|first3=X. L.|last4=Qin|first4=Z.|last5=Fan|first5=H. M.|last6=Lei|first6=X. G.|last7=Liu|first7=H. Y. |last8=Guo|first8=B.|last9=Xu|first9=H. G.|display-authors=8
|pages=385|issue=3|bibcode = 2004EPJA...20..385G |s2cid=120622108}}</ref>
}}
{{isotopes summary/isotope
|mn=266|sym=Bh|hl={{sort|10600|10.6 s}}|ref={{NUBASE2020|ref}}
|dm=α |year=2000|re=<sup>249</sup>Bk(<sup>22</sup>Ne,5n)<ref name="266Bh">{{cite journal|doi=10.1103/PhysRevLett.85.2697|title=Evidence for New Isotopes of Element 107: <sup>266</sup>Bh and <sup>267</sup>Bh|date=2000|author=Wilk, P. A.|journal=Physical Review Letters|volume=85|pages=2697–700|pmid=10991211|last2=Gregorich|first2=K. E.|last3=Turler|first3=A.|last4=Laue|first4=C. A.|last5=Eichler|first5=R.|last6=Ninov V|first6=V.|last7=Adams|first7=J. L.|last8=Kirbach|first8=U. W.|last9=Lane|first9=M. R.|display-authors=8|issue=13|bibcode=2000PhRvL..85.2697W|url=https://zenodo.org/record/1233933|access-date=2018-11-04|archive-date=2019-12-26|archive-url=https://web.archive.org/web/20191226214323/https://zenodo.org/record/1233933|url-status=live}}</ref>
}}
{{isotopes summary/isotope
|mn=267|sym=Bh|hl={{sort|22000|22 s}}|ref={{NUBASE2020|ref}}
|dm=α |year=2000|re=<sup>249</sup>Bk(<sup>22</sup>Ne,4n)<ref name="266Bh" />
}}
{{isotopes summary/isotope
|mn=270|sym=Bh|hl={{sort|144000|2.4 min}}|ref=<ref name=Mc2022>{{Cite journal |title=New isotope <sup>286</sup>Mc produced in the <sup>243</sup>Am+<sup>48</sup>Ca reaction |last1=Oganessian |first1=Yu. Ts. |last2=Utyonkov |first2=V. K. |last3=Kovrizhnykh |first3=N. D. |display-authors=et al. |date=2022 |journal=Physical Review C |volume=106 |number=64306 |page=064306 |doi=10.1103/PhysRevC.106.064306|bibcode=2022PhRvC.106f4306O |s2cid=254435744 |doi-access=free }}</ref>
|dm=α |year=2006|re=<sup>282</sup>Nh(—,3α)<ref name="270Bh">{{cite conference |doi=10.1063/1.2746600 |isbn=978-0-7354-0420-5 |book-title=AIP Conference Proceedings: International Symposium on Exotic Nuclei |date=2007 |last1=Oganessian |first1=Yu. Ts. |editor-last=Penionzhkevich |editor-first=Yu. E. |editor2-last=Cherepanov |editor2-first=E. A. |volume=912 |pages=235 |title=Heaviest Nuclei Produced in 48Ca-induced Reactions (Synthesis and Decay Properties)}}</ref>
}}
{{isotopes summary/isotope
|mn=271|sym=Bh|hl={{sort|2900|2.9 s}}|ref=<ref name=Mc2022/>
|dm=α |year=2003|re=<sup>287</sup>Mc(—,4α)<ref name="270Bh" />
}}
{{isotopes summary/isotope
|mn=272|sym=Bh|hl={{sort|8800|8.8 s}}|ref=<ref name=Mc2022/>
|dm=α |year=2005|re=<sup>288</sup>Mc(—,4α)<ref name="270Bh" />
}}
{{isotopes summary/isotope
|mn=274|sym=Bh|hl={{sort|57000|57 s}}|ref={{NUBASE2020|ref}}
|dm=α |year=2009|re=<sup>294</sup>Ts(—,5α)<ref name="274Bh">{{cite journal|last1=Oganessian |first1=Yuri Ts.|last2=Abdullin |first2=F. Sh.|last3=Bailey |first3=P. D.|display-authors=etal|title=Synthesis of a New Element with Atomic Number ''Z''=117 |date=2010-04-09 |journal=Physical Review Letters |publisher=American Physical Society |volume=104 <!--|issue=14 -->|number=142502 |doi=10.1103/PhysRevLett.104.142502 |pmid=20481935 |bibcode=2010PhRvL.104n2502O |url=https://www.researchgate.net/publication/44610795  }}</ref>
}}
{{isotopes summary/isotope
|mn=278|sym=Bh|hl={{sort|690000|11.5 min?}}|ref=<ref name=Hofmann2016/>
|dm=SF |year=1998?|re=<sup>290</sup>Fl(e<sup>−</sup>,ν<sub>e</sub>3α)?
}}
}}

Bohrium has no stable or naturally occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Twelve different isotopes of bohrium have been reported with atomic masses 260–262, 264–267, 270–272, 274, and 278, one of which, bohrium-262, has a known [[metastable state]]. All of these but the unconfirmed <sup>278</sup>Bh decay only through alpha decay, although some unknown bohrium isotopes are predicted to undergo spontaneous fission.<ref name="nuclidetable">{{cite web |url=http://www.nndc.bnl.gov/chart/reCenter.jsp?z=107&n=163 |title=Interactive Chart of Nuclides |publisher=Brookhaven National Laboratory |author=Sonzogni, Alejandro |location=National Nuclear Data Center |access-date=2008-06-06 |archive-date=2019-04-02 |archive-url=https://web.archive.org/web/20190402195353/https://www.nndc.bnl.gov/nudat2/ |url-status=dead }}</ref>

The lighter isotopes usually have shorter half-lives; half-lives of under 100&nbsp;ms for <sup>260</sup>Bh, <sup>261</sup>Bh, <sup>262</sup>Bh, and <sup>262m</sup>Bh were observed. <sup>264</sup>Bh, <sup>265</sup>Bh, <sup>266</sup>Bh, and <sup>271</sup>Bh are more stable at around 1&nbsp;s, and <sup>267</sup>Bh and <sup>272</sup>Bh have half-lives of about 10&nbsp;s. The heaviest isotopes are the most stable, with <sup>270</sup>Bh and <sup>274</sup>Bh having measured half-lives of about 2.4&nbsp;min and 40&nbsp;s respectively, and the even heavier unconfirmed isotope <sup>278</sup>Bh appearing to have an even longer half-life of about 11.5 minutes.

The most proton-rich isotopes with masses 260, 261, and 262 were directly produced by cold fusion, those with mass 262 and 264 were reported in the decay chains of meitnerium and roentgenium, while the neutron-rich isotopes with masses 265, 266, 267 were created in irradiations of actinide targets. The five most neutron-rich ones with masses 270, 271, 272, 274, and 278 (unconfirmed) appear in the decay chains of <sup>282</sup>Nh, <sup>287</sup>Mc, <sup>288</sup>Mc, <sup>294</sup>Ts, and <sup>290</sup>Fl respectively. The half-lives of bohrium isotopes range from about ten&nbsp;milliseconds for <sup>262m</sup>Bh to about one&nbsp;minute for <sup>270</sup>Bh and <sup>274</sup>Bh, extending to about 11.5 minutes for the unconfirmed <sup>278</sup>Bh, which may have one of the longest half-lives among reported superheavy nuclides.<ref name="Doi_">{{cite book |last1=Münzenberg|first1=G.|last2=Gupta|first2=M. |chapter=Production and Identification of Transactinide Elements |editor-first=Attila |editor-last=Vértes |editor-first2=Sándor |editor-last2=Nagy |editor-first3=Zoltán |editor-last3=Klencsár |editor-first4=Rezső G. |editor-last4=Lovas |editor-first5=Frank |editor-last5=Rösch |title=Handbook of Nuclear Chemistry: Production and Identification of Transactinide Elements |page=877 |date=2011 |doi=10.1007/978-1-4419-0720-2_19 |isbn=978-1-4419-0719-6}}</ref>

==Predicted properties==
Very few properties of bohrium or its compounds have been measured; this is due to its extremely limited and expensive production<ref name="Bloomberg" /> and the fact that bohrium (and its parents) decays very quickly. A few singular chemistry-related properties have been measured, but properties of bohrium metal remain unknown and only predictions are available.

===Chemical===
Bohrium is the fifth member of the 6d series of transition metals and the heaviest member of [[group 7 element|group 7]] in the periodic table, below [[manganese]], [[technetium]] and [[rhenium]]. All the members of the group readily portray their group oxidation state of +7 and the state becomes more stable as the group is descended. Thus bohrium is expected to form a stable +7 state. Technetium also shows a stable +4 state whilst rhenium exhibits stable +4 and +3 states. Bohrium may therefore show these lower states as well.{{Fricke1975}} The higher +7 oxidation state is more likely to exist in oxyanions, such as perbohrate, {{chem|BhO|4|-}}, analogous to the lighter [[permanganate]], [[pertechnetate]], and [[perrhenate]]. Nevertheless, bohrium(VII) is likely to be unstable in aqueous solution, and would probably be easily reduced to the more stable bohrium(IV).<ref name="Haire" />

The lighter group 7 elements are known to form volatile heptoxides M<sub>2</sub>O<sub>7</sub> (M = Mn, Tc, Re), so bohrium should also form the volatile oxide Bh<sub>2</sub>O<sub>7</sub>. The oxide should dissolve in water to form perbohric acid, HBhO<sub>4</sub>.
Rhenium and technetium form a range of oxyhalides from the halogenation of the oxide. The chlorination of the oxide forms the oxychlorides MO<sub>3</sub>Cl, so BhO<sub>3</sub>Cl should be formed in this reaction. Fluorination results in MO<sub>3</sub>F and MO<sub>2</sub>F<sub>3</sub> for the heavier elements in addition to the rhenium compounds ReOF<sub>5</sub> and ReF<sub>7</sub>. Therefore, oxyfluoride formation for bohrium may help to indicate eka-rhenium properties.<ref>Hans Georg Nadler "Rhenium and Rhenium Compounds" Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2000. {{doi|10.1002/14356007.a23_199}}</ref> Since the oxychlorides are asymmetrical, and they should have increasingly large [[dipole]] moments going down the group, they should become less volatile in the order TcO<sub>3</sub>Cl &gt; ReO<sub>3</sub>Cl &gt; BhO<sub>3</sub>Cl: this was experimentally confirmed in 2000 by measuring the [[enthalpy|enthalpies]] of [[adsorption]] of these three compounds. The values are for TcO<sub>3</sub>Cl and ReO<sub>3</sub>Cl are −51&nbsp;kJ/mol and −61&nbsp;kJ/mol respectively; the experimental value for BhO<sub>3</sub>Cl is −77.8&nbsp;kJ/mol, very close to the theoretically expected value of −78.5&nbsp;kJ/mol.<ref name="Haire" />

===Physical and atomic===
Bohrium is expected to be a solid under normal conditions and assume a [[hexagonal close-packed]] crystal structure (<sup>''c''</sup>/<sub>''a''</sub>&nbsp;=&nbsp;1.62), similar to its lighter [[congener (chemistry)|congener]] rhenium.<ref name="hcp" /> Early predictions by Fricke estimated its density at 37.1&nbsp;g/cm<sup>3</sup>,<ref name="Haire" /> but newer calculations predict a somewhat lower value of 26–27&nbsp;g/cm<sup>3</sup>.<ref name="density" /><ref name="kratz" />

The atomic radius of bohrium is expected to be around 128&nbsp;pm.<ref name="Haire" /> Due to the relativistic stabilization of the 7s orbital and destabilization of the 6d orbital, the Bh<sup>+</sup> ion is predicted to have an electron configuration of [Rn] 5f<sup>14</sup> 6d<sup>4</sup> 7s<sup>2</sup>, giving up a 6d electron instead of a 7s electron, which is the opposite of the behavior of its lighter homologues manganese and technetium. Rhenium, on the other hand, follows its heavier congener bohrium in giving up a 5d electron before a 6s electron, as relativistic effects have become significant by the sixth period, where they cause among other things the yellow color of [[gold]] and the low melting point of [[mercury (element)|mercury]]. The Bh<sup>2+</sup> ion is expected to have an electron configuration of [Rn] 5f<sup>14</sup> 6d<sup>3</sup> 7s<sup>2</sup>; in contrast, the Re<sup>2+</sup> ion is expected to have a [Xe] 4f<sup>14</sup> 5d<sup>5</sup> configuration, this time analogous to manganese and technetium.<ref name="Haire" /> The ionic radius of hexacoordinate heptavalent bohrium is expected to be 58&nbsp;pm (heptavalent manganese, technetium, and rhenium having values of 46, 57, and 53&nbsp;pm respectively). Pentavalent bohrium should have a larger ionic radius of 83&nbsp;pm.<ref name="Haire" />

==Experimental chemistry==
In 1995, the first report on attempted isolation of the element was unsuccessful, prompting new theoretical studies to investigate how best to investigate bohrium (using its lighter homologs technetium and rhenium for comparison) and removing unwanted contaminating elements such as the trivalent [[actinide]]s, the [[group 5 element]]s, and [[polonium]].<ref>{{cite journal|title=Chemical Separation Procedure Proposed for Studies of Bohrium|last1=Malmbeck|first1=R.|last2=Skarnemark|first2=G.|last3=Alstad|first3=J.|last4=Fure|first4=K.|last5=Johansson|first5=M.|last6=Omtvedt|first6=J. P.|journal=Journal of Radioanalytical and Nuclear Chemistry|volume=246|pages=349|date=2000|doi=10.1023/A:1006791027906|issue=2|bibcode=2000JRNC..246..349M |s2cid=93640208}}</ref>

In 2000, it was confirmed that although relativistic effects are important, bohrium behaves like a typical group 7 element.<ref>{{cite journal|last1=Gäggeler|first1=H. W.|last2=Eichler|first2=R.|last3=Brüchle|first3=W.|last4=Dressler|first4=R.|last5=Düllmann|first5=Ch. E.|last6=Eichler|first6=B.|last7=Gregorich|first7=K. E.|last8=Hoffman|first8=D. C.|last9=Hübener|first9=S.|display-authors=8 |title=Chemical characterization of bohrium (element 107)|journal=Nature|volume=407|issue=6800|pages=63–5|date=2000|pmid=10993071|doi=10.1038/35024044|bibcode=2000Natur.407...63E|s2cid=4398253}}</ref> A team at the [[Paul Scherrer Institute]] (PSI) conducted a chemistry reaction using six atoms of <sup>267</sup>Bh produced in the reaction between <sup>249</sup>Bk and <sup>22</sup>Ne ions. The resulting atoms were thermalised and reacted with a HCl/O<sub>2</sub> mixture to form a volatile oxychloride. The reaction also produced isotopes of its lighter homologues, technetium (as <sup>108</sup>Tc) and rhenium (as <sup>169</sup>Re). The isothermal adsorption curves were measured and gave strong evidence for the formation of a volatile oxychloride with properties similar to that of rhenium oxychloride. This placed bohrium as a typical member of group 7.<ref name="00Ei01">{{cite web|url=http://www.gsi.de/informationen/wti/library/scientificreport2000/Chemistry/9/r_eichler_jb2000.pdf|title=Gas chemical investigation of bohrium (Bh, element 107)|last=Eichler |first=R. |display-authors=etal |work=GSI Annual Report 2000|access-date=2008-02-29|archive-url=https://web.archive.org/web/20120219002121/http://www.gsi.de/informationen/wti/library/scientificreport2000/Chemistry/9/r_eichler_jb2000.pdf|archive-date=2012-02-19}}</ref> The adsorption enthalpies of the oxychlorides of technetium, rhenium, and bohrium were measured in this experiment, agreeing very well with the theoretical predictions and implying a sequence of decreasing oxychloride volatility down group 7 of TcO<sub>3</sub>Cl &gt; ReO<sub>3</sub>Cl &gt; BhO<sub>3</sub>Cl.<ref name="Haire" />

:2 Bh + 3 {{chem|O|2}} + 2 HCl → 2 {{chem|BhO|3|Cl}} + {{chem|H|2}}

The longer-lived heavy isotopes of bohrium, produced as the daughters of heavier elements, offer advantages for future radiochemical experiments. Although the heavy isotope <sup>274</sup>Bh requires a rare and highly radioactive [[berkelium]] target for its production, the isotopes <sup>272</sup>Bh, <sup>271</sup>Bh, and <sup>270</sup>Bh can be readily produced as daughters of more easily produced [[moscovium]] and [[nihonium]] isotopes.<ref name="Moody">{{cite book |chapter=Synthesis of Superheavy Elements |last1=Moody |first1=Ken |editor1-first=Matthias |editor1-last=Schädel |editor2-first=Dawn |editor2-last=Shaughnessy |title=The Chemistry of Superheavy Elements |publisher=Springer Science & Business Media |edition=2nd |pages=24–8 |isbn=9783642374661|date=2013-11-30 }}</ref>

==Notes==
{{notelist}}

==References==
{{Reflist|30em|refs=
<ref name=IUPAC97>{{Cite journal|doi=10.1351/pac199769122471|title=Names and symbols of transfermium elements (IUPAC Recommendations 1997)|date=1997|journal=Pure and Applied Chemistry|volume=69|pages=2471–2474|issue=12|author=Commission on Nomenclature of Inorganic Chemistry|url=http://publications.iupac.org/pac/pdf/1997/pdf/6912x2471.pdf|access-date=2023-07-11|archive-date=2021-10-11|archive-url=https://web.archive.org/web/20211011132719/http://publications.iupac.org/pac/pdf/1997/pdf/6912x2471.pdf|url-status=live}}</ref>
<ref name="Bloomberg">{{Cite web |last=Subramanian |first=S. |author-link=Samanth Subramanian |date=2019 |title=Making New Elements Doesn't Pay. Just Ask This Berkeley Scientist |url=https://www.bloomberg.com/news/features/2019-08-28/making-new-elements-doesn-t-pay-just-ask-this-berkeley-scientist |archive-url=https://archive.today/20201114183428/https://www.bloomberg.com/news/features/2019-08-28/making-new-elements-doesn-t-pay-just-ask-this-berkeley-scientist |archive-date=November 14, 2020 |url-status=live |access-date=2020-01-18 |website=[[Bloomberg Businessweek]]}}</ref>
}}

== Bibliography ==

* {{cite journal |ref={{sfnref|Audi et al.|2017}} |title=The NUBASE2016 evaluation of nuclear properties |doi=10.1088/1674-1137/41/3/030001 |last1=Audi |first1=G. |last2=Kondev |first2=F. G. |last3=Wang |first3=M. |last4=Huang |first4=W. J. |last5=Naimi |first5=S. |display-authors=3 |journal=Chinese Physics C |volume=41 |issue=3 <!--Citation bot deny-->|pages=030001 |year=2017 
|bibcode=2017ChPhC..41c0001A }}<!--for consistency and specific pages, do not replace with {{NUBASE2016}}-->
* {{cite book|last=Beiser|first=A.|title=Concepts of modern physics|date=2003|publisher=McGraw-Hill|isbn=978-0-07-244848-1|edition=6th|oclc=48965418}}
* {{cite book |last1=Hoffman |first1=D. C. |author-link=Darleane C. Hoffman |last2=Ghiorso |first2=A. |author-link2=Albert Ghiorso |last3=Seaborg |first3=G. T. |title=The Transuranium People: The Inside Story |year=2000 |publisher=[[World Scientific]] |isbn=978-1-78-326244-1 }}
* {{cite book |last=Kragh |first=H. |author-link=Helge Kragh |date=2018 |title=From Transuranic to Superheavy Elements: A Story of Dispute and Creation |publisher=[[Springer Science+Business Media|Springer]] |isbn=978-3-319-75813-8 }}
* {{cite journal|last1=Zagrebaev|first1=V.|last2=Karpov|first2=A.|last3=Greiner|first3=W.|date=2013|title=Future of superheavy element research: Which nuclei could be synthesized within the next few years?|journal=[[Journal of Physics: Conference Series]]|volume=420|issue=1|pages=012001|doi=10.1088/1742-6596/420/1/012001|arxiv=1207.5700|bibcode=2013JPhCS.420a2001Z|s2cid=55434734|issn=1742-6588}}

==External links==
*{{Commons category-inline}}
* [http://www.periodicvideos.com/videos/107.htm Bohrium] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)
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[[Category:Bohrium| ]]
[[Category:Chemical elements]]
[[Category:Transition metals]]
[[Category:Synthetic elements]]
[[Category:Chemical elements with hexagonal close-packed structure]]