View source for Rutherfordium

{{distinguish|Ruthenium}}
{{infobox rutherfordium}}
'''Rutherfordium''' is a [[synthetic element|synthetic chemical element]]; it has [[Chemical symbol|symbol]] '''Rf''' and [[atomic number]] 104. It is named after [[physicist]] [[Ernest Rutherford]]. As a synthetic element, it is not found in nature and can only be made in a [[particle accelerator]]. It is [[radioactive]]; the most stable known [[isotope]], <sup>267</sup>Rf, has a [[half-life]] of about 48 minutes.

In the [[periodic table]], it is a [[d-block]] element and the second of the fourth-row [[transition element]]s. It is in [[period 7]] and is a [[group 4 element]]. Chemistry experiments have confirmed that rutherfordium behaves as the heavier [[Homologous series|homolog]] to [[hafnium]] in group 4. The chemical properties of rutherfordium are characterized only partly. They compare well with the other group 4 elements, even though some calculations had indicated that the element might show significantly different properties due to [[Relativistic quantum chemistry|relativistic effects]].

In the 1960s, small amounts of rutherfordium were produced at [[Joint Institute for Nuclear Research]] in the [[Soviet Union]] and at [[Lawrence Berkeley National Laboratory]] in [[California]].<ref>{{Cite web|url=http://www.rsc.org/periodic-table/element/104/rutherfordium|title=Rutherfordium - Element information, properties and uses {{!}} Periodic Table|website=www.rsc.org|access-date=2016-12-09|archive-date=2020-05-10|archive-url=https://web.archive.org/web/20200510201424/https://www.rsc.org/periodic-table/element/104/rutherfordium|url-status=live}}</ref> Priority of discovery and hence the name of the element [[Element naming controversy|was disputed]] between Soviet and American scientists, and it was not until 1997 that the [[International Union of Pure and Applied Chemistry]] (IUPAC) established rutherfordium as the official name of the element.

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

==History==

===Discovery===
Rutherfordium was reportedly [[discovery of the chemical elements|first detected]] in 1964 at the [[Joint Institute for Nuclear Research]] at [[Dubna]] ([[Soviet Union]] at the time). Researchers there bombarded a [[plutonium]]-242 target with [[neon]]-22 [[ion]]s; a [[spontaneous fission]] activity with half-life 0.3&nbsp;±&nbsp;0.1&nbsp;seconds was detected and assigned to <sup>260</sup>104. Later work found no isotope of element 104 with this half-life, so that this assignment must be considered incorrect.<ref name="93TWG">{{cite journal |title =Discovery of the transfermium elements. Part II: Introduction to discovery profiles. Part III: Discovery profiles of the transfermium elements |date = 1993 |author= Barber, R. C. |author2=Greenwood, N. N. |author3=Hrynkiewicz, A. Z. |author4=Jeannin, Y. P. |author5=Lefort, M. |author6=Sakai, M. |author7=Ulehla, I. |author8=Wapstra, A. P. |author9= Wilkinson, D. H. |journal = Pure and Applied Chemistry| volume = 65 |issue = 8 |pages = 1757–1814 |doi = 10.1351/pac199365081757|s2cid = 195819585 |doi-access= free }}</ref>

In 1966–1969, the experiment was repeated. This time, the reaction products by gradient thermochromatography after conversion to chlorides by interaction with [[zirconium tetrachloride|ZrCl<sub>4</sub>]]. The team identified [[spontaneous fission]] activity contained within a volatile chloride portraying eka-hafnium properties.<ref name="93TWG"/>

:{{nuclide|plutonium|242}} + {{nuclide|neon|22}} → <sup>264−''x''</sup>104 → <sup>264−''x''</sup>104Cl<sub>4</sub>

The researchers considered the results to support the 0.3&nbsp;second half-life. Although it is now known that there is no isotope of element 104 with such a half-life, the chemistry does fit that of element 104, as chloride volatility is much greater in group 4 than in group 3 (or the actinides).<ref name=93TWG/>

In 1969, researchers at [[University of California, Berkeley]] conclusively synthesized the element by bombarding a [[californium]]-249 target with [[carbon-12]] ions and measured the alpha decay of <sup>257</sup>104, correlated with the daughter decay of [[nobelium]]-253:<ref name="69Gh01">{{cite journal |doi = 10.1103/PhysRevLett.22.1317 |title = Positive Identification of Two Alpha-Particle-Emitting Isotopes of Element 104 |date = 1969 |last1 = Ghiorso |first1 = A. |last2 = Nurmia |first2 = M. |journal = Physical Review Letters |volume = 22 |issue = 24 |pages = 1317–1320 |bibcode = 1969PhRvL..22.1317G |last3 = Harris |first3 = J. |last4 = Eskola |first4 = K. |last5 = Eskola |first5 = P. |url = https://cloudfront.escholarship.org/dist/prd/content/qt3fm666nq/qt3fm666nq.pdf |access-date = 2019-04-05 |archive-date = 2018-07-22 |archive-url = https://web.archive.org/web/20180722035431/https://cloudfront.escholarship.org/dist/prd/content/qt3fm666nq/qt3fm666nq.pdf |url-status = live }}</ref>
:{{nuclide|californium|249}} + {{nuclide|carbon|12}} → <sup>257</sup>104 + 4 {{SubatomicParticle|neutron}}

They were unable to confirm the 0.3-second half-life for <sup>260</sup>104, and instead found a 10–30 millisecond half-life for this isotope, agreeing with the modern value of 21 milliseconds. In 1970, the American team chemically identified element 104 using the ion-exchange separation method, proving it to be a group 4 element and the heavier homologue of hafnium.<ref name=responses/>

The American synthesis was independently confirmed in 1973 and secured the identification of rutherfordium as the parent by the observation of [[K-alpha]] [[X-rays]] in the elemental signature of the <sup>257</sup>104 decay product, nobelium-253.<ref name="73Be01">{{cite journal |doi =10.1103/PhysRevLett.31.647 |title =X-Ray Identification of Element 104 |date =1973 |author =Bemis, C. E. |journal =Physical Review Letters |volume =31 |issue =10 |pages =647–650 |bibcode=1973PhRvL..31..647B |last2 =Silva |first2 =R. |last3 =Hensley |first3 =D. |last4 =Keller |first4 =O. |last5 =Tarrant |first5 =J. |last6 =Hunt |first6 =L. |last7 =Dittner |first7 =P. |last8 =Hahn |first8 =R. |last9 =Goodman |first9 =C. }}</ref>

===Naming controversy===
{{Main|Transfermium Wars}}
[[File:Ernest Rutherford2.jpg|thumb|left|upright|Element 104 was eventually named after [[Ernest Rutherford]]]]
[[File:Igor Kurchatov 001.png|thumb|left|upright|Igor Kurchatov]]
As a consequence of the initial competing claims of discovery, an [[element naming controversy]] arose. Since the Soviets claimed to have first detected the new element they suggested the name ''kurchatovium'' (Ku) in honor of [[Igor Kurchatov]] (1903–1960), former head of [[Soviet nuclear research]]. This name had been used in books of the [[Soviet Bloc]] as the official name of the element. The Americans, however, proposed ''rutherfordium'' (Rf) for the new element to honor [[New Zealand]] physicist [[Ernest Rutherford]], who is known as the "father" of [[nuclear physics]].<ref>{{cite web |url=http://www.rsc.org/chemistryworld/podcast/Interactive_Periodic_Table_Transcripts/Rutherfordium.asp |title=Rutherfordium |publisher=Rsc.org |access-date=2010-09-04 |archive-date=2011-04-08 |archive-url=https://web.archive.org/web/20110408194724/http://www.rsc.org/chemistryworld/podcast/Interactive_Periodic_Table_Transcripts/Rutherfordium.asp |url-status=live }}</ref> In 1992, the [[International Union of Pure and Applied Chemistry|IUPAC]]/[[International Union of Pure and Applied Physics|IUPAP]] Transfermium Working Group (TWG) assessed the claims of discovery and concluded that both teams provided contemporaneous evidence to the synthesis of element 104 in 1969, and that credit should be shared between the two groups. In particular, this involved the TWG performing a new retrospective reanalysis of the Russian work in the face of the later-discovered fact that there is no 0.3-second isotope of element 104: they reinterpreted the Dubna results as having been caused by a spontaneous fission branch of <sup>259</sup>104.<ref name="93TWG" />

The American group wrote a scathing response to the findings of the TWG, stating that they had given too much emphasis on the results from the Dubna group. In particular they pointed out that the Russian group had altered the details of their claims several times over a period of 20 years, a fact that the Russian team does not deny. They also stressed that the TWG had given too much credence to the chemistry experiments performed by the Russians, considered the TWG's retrospective treatment of the Russian work based on unpublished documents to have been "highly irregular", noted that there was no proof that <sup>259</sup>104 had a spontaneous fission branch at all<ref name=responses/> (as of 2021 there still is not),{{NUBASE2020|ref}} and accused the TWG of not having appropriately qualified personnel on the committee. The TWG responded by saying that this was not the case and having assessed each point raised by the American group said that they found no reason to alter their conclusion regarding priority of discovery.<ref name=responses>{{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>

The International Union of Pure and Applied Chemistry ([[IUPAC]]) adopted ''unnilquadium'' (Unq) as a temporary, [[systematic element name]], derived from the Latin names for digits 1, 0, and 4. In 1994, IUPAC suggested a set of names for elements 104 through 109, in which ''dubnium'' (Db) became element 104 and ''rutherfordium'' became element 106.<ref name="1994 IUPAC">{{Cite journal|year=1994|title=Names and symbols of transfermium elements (IUPAC Recommendations 1994)|url=https://www.iupac.org/publications/pac-2007/1994/pdf/6612x2419.pdf|journal=Pure and Applied Chemistry|volume=66|issue=12|pages=2419–2421|doi=10.1351/pac199466122419|access-date=September 7, 2016|url-status=live|archive-url=https://web.archive.org/web/20170922194905/https://www.iupac.org/publications/pac-2007/1994/pdf/6612x2419.pdf|archive-date=September 22, 2017}}</ref> This recommendation was criticized by the American scientists for several reasons. Firstly, their suggestions were scrambled: the names ''rutherfordium'' and ''hahnium'', originally suggested by Berkeley for elements 104 and 105, were respectively reassigned to elements 106 and 108. Secondly, elements 104 and 105 were given names favored by JINR, despite earlier recognition of LBL as an equal co-discoverer for both of them. Thirdly and most importantly, IUPAC rejected the name ''[[seaborgium]]'' for element 106, having just approved a rule that an element could not be named after a living person, even though the IUPAC had given the LBNL team the sole credit for its discovery.<ref>{{Cite web|url=http://www2.lbl.gov/Science-Articles/Archive/seaborgium-dispute.html|title=Naming of element 106 disputed by international committee|last=Yarris|first=L.|year=1994|access-date=September 7, 2016|archive-date=July 1, 2016|archive-url=https://web.archive.org/web/20160701203756/http://www2.lbl.gov/Science-Articles/Archive/seaborgium-dispute.html|url-status=live}}</ref> In 1997, IUPAC renamed elements 104 to 109, and gave elements 104 and 106 the Berkeley proposals ''rutherfordium'' and ''seaborgium''. The name ''[[dubnium]]'' was given to element 105 at the same time. The 1997 names were accepted by researchers and became the standard.<ref name="97IUPAC">{{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 |issue = 12 |pages =2471–2474|doi-access =free }}</ref>
{{clear}}

==Isotopes==
{{Main|Isotopes of rutherfordium}}
Rutherfordium 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. Seventeen different isotopes have been reported with atomic masses from 252 to 270 (with the exceptions of 264 and 269). Most of these decay predominantly through spontaneous fission, particularly isotopes with [[even and odd atomic nuclei|even neutron numbers]], while some of the lighter isotopes with odd neutron numbers also have significant alpha decay branches.<ref name="nuclidetable" /><ref name="isotopes">{{cite web | title=Six New Isotopes of the Superheavy Elements Discovered | website=Berkeley Lab News Center | date=26 October 2010 | url=https://newscenter.lbl.gov/2010/10/26/six-new-isotopes/ | access-date=5 April 2019}}</ref> 

===Stability and half-lives===
Out of isotopes whose half-lives are known, the lighter isotopes usually have shorter half-lives. The three lightest known isotopes have half-lives of under 50&nbsp;μs, with the lightest reported isotope <sup>252</sup>Rf having a half-life shorter than one microsecond.<ref name=252Rf>{{cite journal |first1=J. |last1=Khuyagbaatar |first2=P. |last2=Mosat |first3=J. |last3=Ballof |first4=R. A. |last4=Cantemir |first5=Ch. E. |last5=Düllmann |first6=K. |last6=Hermainski |first7=F. P. |last7=Heßberger |first8=E. |last8=Jäger |first9=B. |last9=Kindler |first10=J. |last10=Krier |first11=N. |last11=Kurz |first12=S. |last12=Löchner |first13=B. |last13=Lommel |first14=B. |last14=Schausten |first15=Y. |last15=Wei |first16=P. |last16=Wieczorek |first17=A. |last17=Yakushev |display-authors=3 |title=Stepping into the sea of instability: The new sub-𝜇s superheavy nucleus <sup>252</sup>Rf |journal=Physical Review Letters |date=2025 |volume=134 |number=22501 |page=022501 |doi=10.1103/PhysRevLett.134.022501|arxiv=2501.08955 }}</ref><ref name="253Rf-2022">{{cite journal |last1=Lopez-Martens |first1=A. |last2=Hauschild |first2=K. |last3=Svirikhin |first3=A. I. |last4=Asfari |first4=Z. |last5=Chelnokov |first5=M. L. |last6=Chepigin |first6=V. I. |last7=Dorvaux |first7=O. |last8=Forge |first8=M. |last9=Gall |first9=B. |last10=Isaev |first10=A. V. |last11=Izosimov |first11=I. N. |last12=Kessaci |first12=K. |last13=Kuznetsova |first13=A. A. |last14=Malyshev |first14=O. N. |last15=Mukhin |first15=R. S. |last16=Popeko |first16=A. G. |last17=Popov |first17=Yu. A. |last18=Sailaubekov |first18=B. |last19=Sokol |first19=E. A. |last20=Tezekbayeva |first20=M. S. |last21=Yeremin |first21=A. V. |display-authors=3 |title=Fission properties of Rf 253 and the stability of neutron-deficient Rf isotopes |journal=Physical Review C |date=22 February 2022 |volume=105 |issue=2 |doi=10.1103/PhysRevC.105.L021306 |url=https://journals.aps.org/prc/pdf/10.1103/PhysRevC.105.L021306 |access-date=16 June 2023 |language=en |issn=2469-9985|arxiv=2202.11802 |s2cid=247072308 }}</ref> The isotopes <sup>256</sup>Rf, <sup>258</sup>Rf, <sup>260</sup>Rf are more stable at around 10&nbsp;ms; <sup>255</sup>Rf, <sup>257</sup>Rf, <sup>259</sup>Rf, and <sup>262</sup>Rf live between 1 and 5 seconds; and <sup>261</sup>Rf, <sup>265</sup>Rf, and <sup>263</sup>Rf are more stable, at around 1.1, 1.5, and 10 minutes respectively. The most stable known isotope, <sup>267</sup>Rf, is one of the heaviest, and has a half-life of about 48 minutes.<ref name="PuCa2022b">{{cite journal |title=Investigation of <sup>48</sup>Ca-induced reactions with <sup>242</sup>Pu and <sup>238</sup>U targets at the JINR Superheavy Element Factory |journal=Physical Review C |volume=106 |number=24612 |year=2022 |first1=Yu. Ts. |last1=Oganessian |first2=V. K. |last2=Utyonkov |first3=D. |last3=Ibadullayev |page=024612 |display-authors=et al. |doi= 10.1103/PhysRevC.106.024612|bibcode=2022PhRvC.106b4612O |osti=1883808 |s2cid=251759318}}</ref> Rutherfordium isotopes with an odd neutron number tend to have longer half-lives than their even–even neighbors because the odd neutron provides additional hindrance against spontaneous fission.

The lightest isotopes were synthesized by direct fusion between two lighter nuclei and as decay products. The heaviest isotope produced by direct fusion is <sup>262</sup>Rf; heavier isotopes have only been observed as decay products of elements with larger atomic numbers. The heavy isotopes <sup>266</sup>Rf and <sup>268</sup>Rf have also been reported as [[electron capture]] daughters of the [[dubnium]] isotopes <sup>266</sup>Db and <sup>268</sup>Db, but have short half-lives to [[spontaneous fission]]. It seems likely that the same is true for <sup>270</sup>Rf, a possible daughter of <sup>270</sup>Db.<ref name="270Rf">{{cite book|last=Stock|first=Reinhard|title=Encyclopedia of Nuclear Physics and its Applications|url=https://books.google.com/books?id=zVrdAAAAQBAJ&pg=PT305|date=13 September 2013|publisher=John Wiley & Sons|isbn=978-3-527-64926-6|page=305|oclc=867630862}}</ref> These three isotopes remain unconfirmed.

In 1999, American scientists at the University of California, Berkeley, announced that they had succeeded in synthesizing three atoms of <sup>293</sup>Og.<ref>{{cite journal |last=Ninov |first=Viktor |display-authors=etal |title=Observation of Superheavy Nuclei Produced in the Reaction of {{SimpleNuclide|Krypton|86}} with {{SimpleNuclide|Lead|208}} |journal=[[Physical Review Letters]] |volume=83 |issue=6 |pages=1104–1107 |date=1999 |doi=10.1103/PhysRevLett.83.1104 |bibcode=1999PhRvL..83.1104N |url=https://zenodo.org/record/1233919 |access-date=2018-11-04 |archive-date=2023-07-18 |archive-url=https://web.archive.org/web/20230718161424/https://zenodo.org/record/1233919 |url-status=live }}</ref> These parent nuclei were reported to have successively emitted seven alpha particles to form <sup>265</sup>Rf nuclei, but their claim was retracted in 2001.<ref>{{cite web | title=Results of Element 118 Experiment Retracted | website=Berkeley Lab Research News | date=2001-07-21 | url=http://enews.lbl.gov/Science-Articles/Archive/118-retraction.html | archive-url=https://web.archive.org/web/20080129191344/http://enews.lbl.gov/Science-Articles/Archive/118-retraction.html | archive-date=29 January 2008 | access-date=5 April 2019 |df=dmy-all}}</ref> This isotope was later discovered in 2010 as the final product in the decay chain of <sup>285</sup>Fl.<ref name="PuCa2017" /><ref name="10El">{{cite journal|last1=Ellison|first1=P.|last2=Gregorich|first2=K.|last3=Berryman|first3=J.|last4=Bleuel|first4=D.|last5=Clark|first5=R.|last6=Dragojević|first6=I.|last7=Dvorak|first7=J.|last8=Fallon|first8=P.|last9=Fineman-Sotomayor|first9=C.|display-authors=etal|title=New Superheavy Element Isotopes: <sup>242</sup>Pu(<sup>48</sup>Ca,5n)<sup>285</sup>114|journal=Physical Review Letters|volume=105|year=2010|doi=10.1103/PhysRevLett.105.182701|bibcode=2010PhRvL.105r2701E|pmid=21231101|issue=18|page=182701|url=https://digital.library.unt.edu/ark:/67531/metadc831769/|access-date=2019-07-14|archive-date=2019-07-02|archive-url=https://web.archive.org/web/20190702153317/https://digital.library.unt.edu/ark:/67531/metadc831769/|url-status=live}}</ref>

==Predicted properties==
<!---http://www.rsc.org/chemistryworld/podcast/Interactive_Periodic_Table_Transcripts/Rutherfordium.asp--->

Very few properties of rutherfordium or its compounds have been measured; this is due to its extremely limited and expensive production<ref name="Bloomberg">{{Cite web|url=https://www.bloomberg.com/news/features/2019-08-28/making-new-elements-doesn-t-pay-just-ask-this-berkeley-scientist|title=Making New Elements Doesn't Pay. Just Ask This Berkeley Scientist|last=Subramanian|first=S.|website=[[Bloomberg Businessweek]]|access-date=2020-01-18|archive-date=2020-11-14|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|url-status=live}}</ref> and the fact that rutherfordium (and its parents) decays very quickly. A few singular chemistry-related properties have been measured, but properties of rutherfordium metal remain unknown and only predictions are available.

===Chemical===
Rutherfordium is the first [[transactinide element]] and the second member of the 6d series of transition metals. Calculations on its [[ionization potential]]s, [[atomic radius]], as well as radii, orbital energies, and ground levels of its ionized states are similar to that of [[hafnium]] and very different from that of [[lead]]. Therefore, it was concluded that rutherfordium's basic properties will resemble those of other [[group 4 element]]s, below [[titanium]], [[zirconium]], and hafnium.<ref name="Rf263">{{cite journal |url=http://www.ulrich-rieth.de/publikationen/RCA0301_059.PDF |title=An EC-branch in the decay of 27-s<sup>263</sup>Db: Evidence for the new isotope <sup>263</sup>Rf |author=Kratz, J. V. |journal=Radiochim. Acta |volume=91 |issue=1–2003 |pages=59–62 |date=2003 |doi=10.1524/ract.91.1.59.19010 |last2=Nähler |first2=A. |last3=Rieth |first3=U. |last4=Kronenberg |first4=A. |last5=Kuczewski |first5=B. |last6=Strub |first6=E. |last7=Brüchle |first7=W. |last8=Schädel |first8=M. |last9=Schausten |first9=B. |last10=Türler |first10=A. |last11=Gäggeler |first11=H. W. |last12=Jost |first12=D. T. |last13=Gregorich |first13=K. E. |last14=Nitsche |first14=H. |last15=Laue |first15=C. |last16=Sudowe |first16=R. |last17=Wilk |first17=P. A. |s2cid=96560109 |display-authors=8 |archive-url=https://web.archive.org/web/20090225154858/http://www.ulrich-rieth.de/publikationen/RCA0301_059.PDF |archive-date=2009-02-25 }}</ref><ref name="Kratz03" /> Some of its properties were determined by gas-phase experiments and aqueous chemistry. The oxidation state +4 is the only stable state for the latter two elements and therefore rutherfordium should also exhibit a stable +4 state.<ref name="Kratz03" /> In addition, rutherfordium is also expected to be able to form a less stable +3 state.<ref name="Haire" /> The [[standard reduction potential]] of the Rf<sup>4+</sup>/Rf couple is predicted to be higher than −1.7&nbsp;V.{{Fricke1975}}

Initial predictions of the chemical properties of rutherfordium were based on calculations which indicated that the relativistic effects on the electron shell might be strong enough that the [[p orbital|7p orbitals]] would have a lower energy level than the [[d orbital|6d orbitals]], giving it a [[valence electron]] configuration of 6d<sup>1</sup> 7s<sup>2</sup> 7p<sup>1</sup> or even 7s<sup>2</sup> 7p<sup>2</sup>, therefore making the element behave more like [[lead]] than hafnium. With better calculation methods and experimental studies of the chemical properties of rutherfordium compounds it could be shown that this does not happen and that rutherfordium instead behaves like the rest of the [[group 4 element]]s.<ref name="Haire" /><ref name="Kratz03">{{cite journal|doi=10.1351/pac200375010103 |url=http://stage.iupac.org/originalWeb/publications/pac/2003/pdf/7501x0103.pdf |title=Critical evaluation of the chemical properties of the transactinide elements (IUPAC Technical Report) |date=2003 |last1=Kratz |first1=J. V. |journal=Pure and Applied Chemistry |volume=75 |issue=1 |page=103 |s2cid=5172663 |archive-url=https://web.archive.org/web/20110726195721/http://stage.iupac.org/originalWeb/publications/pac/2003/pdf/7501x0103.pdf |archive-date=2011-07-26}}</ref> Later it was shown in ab initio calculations with the high level of accuracy<ref name="Eliav1995">{{cite journal |last1=Eliav |first1=E. |last2=Kaldor |first2=U. |last3=Ishikawa |first3=Y. |title=Ground State Electron Configuration of Rutherfordium: Role of Dynamic Correlation |journal=Physical Review Letters |volume=74 |issue=7 |pages=1079–1082 |year=1995 |doi=10.1103/PhysRevLett.74.1079 |pmid=10058929 |bibcode=1995PhRvL..74.1079E}}</ref><ref name="Mosyagin2010">{{cite journal |last1=Mosyagin |first1=N. S. |last2=Tupitsyn |first2=I. I. |last3=Titov |first3=A. V. |title=Precision Calculation of the Low-Lying Excited States of the Rf Atom |journal=Radiochemistry |volume=52 |issue=4 |pages=394–398 |year=2010 |doi=10.1134/S1066362210040120 |bibcode=2010Radch..52..394M |s2cid=120721050 }}</ref><ref name="Dzuba2014">{{cite journal |last1=Dzuba |first1=V. A. |last2=Safronova |first2=M. S. |last3=Safronova |first3=U. I. |title=Atomic properties of superheavy elements No, Lr, and Rf |journal=Physical Review A |volume=90 |issue=1 |page=012504 |year=2014 |doi=10.1103/PhysRevA.90.012504 |arxiv=1406.0262 |bibcode=2014PhRvA..90a2504D |s2cid=74871880}}</ref> that the Rf atom has the ground state with the 6d<sup>2</sup> 7s<sup>2</sup> valence configuration and the low-lying excited 6d<sup>1</sup> 7s<sup>2</sup> 7p<sup>1</sup> state with the excitation energy of only 0.3–0.5 eV.

In an analogous manner to zirconium and hafnium, rutherfordium is projected to form a very stable, [[refractory]] oxide, RfO<sub>2</sub>. It reacts with halogens to form tetrahalides, RfX<sub>4</sub>, which hydrolyze on contact with water to form oxyhalides RfOX<sub>2</sub>. The tetrahalides are volatile solids existing as monomeric tetrahedral molecules in the vapor phase.<ref name="Kratz03" />

In the aqueous phase, the Rf<sup>4+</sup> ion hydrolyzes less than titanium(IV) and to a similar extent as zirconium and hafnium, thus resulting in the RfO<sup>2+</sup> ion. Treatment of the halides with halide ions promotes the formation of complex ions. The use of chloride and bromide ions produces the hexahalide complexes {{chem|RfCl|6|2-}} and {{chem|RfBr|6|2-}}. For the fluoride complexes, zirconium and hafnium tend to form hepta- and octa- complexes. Thus, for the larger rutherfordium ion, the complexes {{chem|RfF|6|2-}}, {{chem|RfF|7|3-}} and {{chem|RfF|8|4-}} are possible.<ref name="Kratz03" />

===Physical and atomic===
<section begin=properties />
Rutherfordium is expected to be a solid under normal conditions and have a [[hexagonal close-packed]] crystal structure (<sup>''c''</sup>/<sub>''a''</sub>&nbsp;=&nbsp;1.61), similar to its lighter [[congener (chemistry)|congener]] hafnium.<ref name="hcp" /> It should be a metal with [[density]] ~17&nbsp;g/cm<sup>3</sup>.<ref name=density>{{cite journal |last1=Gyanchandani |first1=Jyoti |last2=Sikka |first2=S. K. |title=Physical properties of the 6 d -series elements from density functional theory: Close similarity to lighter transition metals |journal=Physical Review B |date=10 May 2011 |volume=83 |issue=17 |page=172101 |doi=10.1103/PhysRevB.83.172101 |bibcode=2011PhRvB..83q2101G }}</ref><ref name=kratz>{{cite book |last1=Kratz |last2=Lieser |title=Nuclear and Radiochemistry: Fundamentals and Applications |date=2013 |page=631 |edition=3rd}}</ref> The atomic radius of rutherfordium is expected to be ~150&nbsp;[[picometer|pm]]. Due to relativistic stabilization of the 7s orbital and destabilization of the 6d orbital, Rf<sup>+</sup> and Rf<sup>2+</sup> ions are predicted to give up 6d electrons instead of 7s electrons, which is the opposite of the behavior of its lighter homologs.<ref name="Haire" /> When under high pressure (variously calculated as 72 or ~50 [[gigapascal|GPa]]), rutherfordium is expected to transition to [[body-centered cubic]] crystal structure; hafnium transforms to this structure at 71±1&nbsp;GPa, but has an intermediate ω structure that it transforms to at 38±8&nbsp;GPa that should be lacking for rutherfordium.<ref>{{cite journal | last1=Gyanchandani | first1=Jyoti | last2=Sikka | first2=S.K. | title=Structural properties of rutherfordium: An ab-initio study | journal=Physics Letters A | volume=376 | issue=4 | date=2012 | doi=10.1016/j.physleta.2011.11.053 | pages=620–625 |arxiv=1106.3146| bibcode=2012PhLA..376..620G }}</ref><section end=properties />

==Experimental chemistry==
===Gas phase===
[[File:RfCl4.png|class=skin-invert-image|thumb|upright=0.5|The tetrahedral structure of the RfCl<sub>4</sub> molecule]]
Early work on the study of the chemistry of rutherfordium focused on gas thermochromatography and measurement of relative deposition temperature adsorption curves. The initial work was carried out at Dubna in an attempt to reaffirm their discovery of the element. Recent work is more reliable regarding the identification of the parent rutherfordium radioisotopes. The isotope <sup>261m</sup>Rf has been used for these studies,<ref name="Kratz03" /> though the long-lived isotope <sup>267</sup>Rf (produced in the decay chain of <sup>291</sup>Lv, <sup>287</sup>Fl, and <sup>283</sup>Cn) may be advantageous for future experiments.<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=978-3-642-37466-1|date=2013-11-30 }}</ref> The experiments relied on the expectation that rutherfordium would be a 6d element in group 4 and should therefore form a volatile molecular tetrachloride, that would be tetrahedral in shape.<ref name="Kratz03" /><ref name="autogenerated1">{{cite journal |last1=Oganessian |first1=Yury Ts |last2=Dmitriev |first2=Sergey N. |title=Superheavy elements in D I Mendeleev's Periodic Table |journal=Russian Chemical Reviews |volume=78 |issue=12 |page=1077 |date=2009 |doi=10.1070/RC2009v078n12ABEH004096 |bibcode = 2009RuCRv..78.1077O |s2cid=250848732 }}</ref><ref>{{cite journal |doi = 10.1016/S0925-8388(98)00072-3 |title =Evidence for relativistic effects in the chemistry of element 104 |first9 = D. |last10 =Timokhin |first10 = S. N. |last11 =Yakushev |first11 = A. B. |last12 =Zvara |first12 =I. |last9 = Piguet |first8 = V. Ya. |last8 = Lebedev |first7 = D. T. |last7 = Jost |first6 = S. |last6 = Hübener |first5 = M. |last5 = Grantz |first4 = H. W. |last4 = Gäggeler |first3 = B. |last3 = Eichler |first2 = G. V. |date = 1998 |last2 = Buklanov |last1 = Türler| first1 = A. | journal = Journal of Alloys and Compounds |volume = 271–273 |page = 287| display-authors=8}}</ref> Rutherfordium(IV) chloride is more volatile than its lighter homologue [[hafnium(IV) chloride]] (HfCl<sub>4</sub>) because its bonds are more [[covalent bond|covalent]].<ref name="Haire" />

A series of experiments confirmed that rutherfordium behaves as a typical member of group 4, forming a tetravalent chloride (RfCl<sub>4</sub>) and bromide (RfBr<sub>4</sub>) as well as an oxychloride (RfOCl<sub>2</sub>). A decreased volatility was observed for {{chem|RfCl|4}} when [[potassium chloride]] is provided as the solid phase instead of gas, highly indicative of the formation of nonvolatile {{chem|K|2|RfCl|6}} mixed salt.<ref name="Rf263" /><ref name="Kratz03" /><ref>{{cite web|url=http://lch.web.psi.ch/files/lectures/TexasA&M/TexasA&M.pdf |title=Lecture Course Texas A&M: Gas Phase Chemistry of Superheavy Elements |date=2007-11-05 |access-date=2010-03-30 |first=Heinz W. |last=Gäggeler |archive-url=https://web.archive.org/web/20120220090755/http://lch.web.psi.ch/files/lectures/TexasA%26M/TexasA%26M.pdf |archive-date=2012-02-20 }}</ref>

===Aqueous phase===
Rutherfordium is expected to have the electron configuration [Rn]5f<sup>14</sup> 6d<sup>2</sup> 7s<sup>2</sup> and therefore behave as the heavier homologue of [[hafnium]] in group 4 of the periodic table. It should therefore readily form a hydrated Rf<sup>4+</sup> ion in strong acid solution and should readily form complexes in [[hydrochloric acid]], [[hydrobromic acid|hydrobromic]] or [[hydrofluoric acid]] solutions.<ref name="Kratz03" />

The most conclusive aqueous chemistry studies of rutherfordium have been performed by the Japanese team at [[Japan Atomic Energy Research Institute]] using the isotope <sup>261m</sup>Rf. Extraction experiments from hydrochloric acid solutions using isotopes of rutherfordium, hafnium, zirconium, as well as the pseudo-group 4 element [[thorium]] have proved a non-actinide behavior for rutherfordium. A comparison with its lighter homologues placed rutherfordium firmly in group 4 and indicated the formation of a hexachlororutherfordate complex in chloride solutions, in a manner similar to hafnium and zirconium.<ref name="Kratz03" /><ref>{{cite journal | doi=10.1524/ract.2005.93.9-10.519 | title=Chemical studies on rutherfordium (Rf) at JAERI | date=2005 | last1=Nagame | first1=Y. | journal=Radiochimica Acta | volume=93 | issue=9–10_2005 | page=519 | url=http://wwwsoc.nii.ac.jp/jnrs/paper/JN62/jn6202.pdf | last2=Tsukada | first2=K. | last3=Asai | first3=M. | last4=Toyoshima | first4=A. | last5=Akiyama | first5=K. | last6=Ishii | first6=Y. | last7=Kaneko-Sato | first7=T. | last8=Hirata | first8=M. | last9=Nishinaka | first9=I. | last10=Ichikawa | first10=S. | last11=Haba | first11=H. | last12=Enomoto | first12=Shuichi | s2cid=96299943 | display-authors=1 | archive-url=https://web.archive.org/web/20080528125634/http://wwwsoc.nii.ac.jp/jnrs/paper/JN62/jn6202.pdf | archive-date=2008-05-28 }}</ref>

:{{chem|261m|Rf|4+}} + 6 {{chem|Cl|-}} → {{chem|[|<sup>261m</sup>RfCl|6|]|2-}}

Very similar results were observed in hydrofluoric acid solutions. Differences in the extraction curves were interpreted as a weaker affinity for fluoride ion and the formation of the hexafluororutherfordate ion, whereas hafnium and zirconium ions complex seven or eight fluoride ions at the concentrations used:<ref name="Kratz03" />

:{{chem|261m|Rf|4+}} + 6 {{chem|F|-}} → {{chem|[|<sup>261m</sup>RfF|6|]|2-}}

Experiments performed in mixed sulfuric and nitric acid solutions shows that rutherfordium has a much weaker affinity towards forming sulfate complexes than hafnium. This result is in agreement with predictions, which expect rutherfordium complexes to be less stable than those of zirconium and hafnium because of a smaller ionic contribution to the bonding. This arises because rutherfordium has a larger ionic radius (76&nbsp;pm) than zirconium (71&nbsp;pm) and hafnium (72&nbsp;pm), and also because of relativistic stabilisation of the 7s orbital and destabilisation and spin–orbit splitting of the 6d orbitals.<ref>{{cite journal |last1=Li |first1=Z. J. |last2=Toyoshima |first2=A. |first3=M. |last3=Asai |first4=K. |last4=Tsukada |first5=T. K. |last5=Sato |first6=N. |last6=Sato |first7=T. |last7=Kikuchi |first8=Y. |last8=Nagame |first9=M. |last9=Schädel |first10=V. |last10=Pershina |first11=X. H. |last11=Liang |first12=Y. |last12=Kasamatsu |first13=Y. |last13=Komori |first14=K. |last14=Ooe |first15=A. |last15=Shinohara |first16=S. |last16=Goto |first17=H. |last17=Murayama |first18=M. |last18=Murakami |first19=H. |last19=Kudo |first20=H. |last20=Haba |first21=Y. |last21=Takeda |first22=M. |last22=Nishikawa |first23=A. |last23=Yokoyama |first24=S. |last24=Ikarashi |first25=K. |last25=Sueki |first26=K. |last26=Akiyama |first27=J. V. |last27=Kratz |display-authors=3 |date=2012 |title=Sulfate complexation of element 104, Rf, in H<sub>2</sub>SO<sub>4</sub>/HNO<sub>3</sub> mixed solution |url= |journal=Radiochimica Acta |volume=100 |issue=3 |pages=157–164 |doi=10.1524/ract.2012.1898 |s2cid=100852185 }}</ref>

Coprecipitation experiments performed in 2021 studied rutherfordium's behaviour in basic solution containing [[ammonia]] or [[sodium hydroxide]], using zirconium, hafnium, and thorium as comparisons. It was found that rutherfordium does not strongly coordinate with ammonia and instead coprecipitates out as a hydroxide, which is probably Rf(OH)<sub>4</sub>.<ref>{{cite journal |last1=Kasamatsu |first1=Yoshitaka |last2=Toyomura |first2=Keigo |first3=Hiromitsu |last3=Haba |first4=Takuya |last4=Yokokita |first5=Yudai |last5=Shigekawa |first6=Aiko |last6=Kino |first7=Yuki |last7=Yasuda |first8=Yukiko |last8=Komori |first9=Jumpei |last9=Kanaya |first10=Minghui |last10=Huang |first11=Masashi |last11=Murakami |first12=Hidetoshi |last12=Kikunaga |first13=Eisuke |last13=Watanabe |first14=Takashi |last14=Yoshimura |first15=Kosuke |last15=Morita |first16=Toshiaki |last16=Mitsugashira |first17=Koichi |last17=Takamiya |first18=Tsutomu |last18=Ohtsuki |first19=Atsushi |last19=Shinohara |display-authors=3 |date=2021 |title=Co-precipitation behaviour of single atoms of rutherfordium in basic solutions |url= |journal=Nature Chemistry |volume=13 |issue= 3|pages=226–230 |doi=10.1038/s41557-020-00634-6 |pmid=33589784 |bibcode=2021NatCh..13..226K |s2cid=231931604 }}</ref>

==Notes==
{{Notelist}}

==References==
{{Reflist|30em}}

== Bibliography ==
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|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|page=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/104.htm Rutherfordium] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)
* [http://www.webelements.com/webelements/elements/text/Rf/index.html WebElements.com – Rutherfordium]

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