View source for Physics:Transactinide element

{{periodic table (micro)|title=Transactinide elements<br/>in the periodic table|caption=''Z''&nbsp;≥&nbsp;104|mark=Rf,Db,Sg,Bh,Hs,Mt,Ds,Rg,Cn,Nh,Fl,Mc,Lv,Ts,Og}}
In [[Chemistry:Chemistry|chemistry]], '''transactinide elements''' (also, '''transactinides''', or '''super-heavy elements''') are the [[Chemistry:Chemical element|chemical element]]s with [[Physics:Atomic number|atomic number]]s from 104 to 120. Their atomic numbers are immediately greater than those of the [[Chemistry:Actinide|actinide]]s, the heaviest of which is [[Chemistry:Lawrencium|lawrencium]] (atomic number 103).

[[Biography:Glenn T. Seaborg|Glenn T. Seaborg]] first proposed the actinide concept, which led to the acceptance of the actinide series. He also proposed the  transactinide series ranging from element 104 to 121 and the superactinide series approximately spanning elements 122 to 153. The transactinide [[Chemistry:Seaborgium|seaborgium]] was named in his honor.<ref>[http://www.iupac.org/reports/provisional/abstract04/connelly_310804.html IUPAC Provisional Recommendations for the Nomenclature of Inorganic Chemistry (2004)] (online draft of an updated version of the "''Red Book''" IR 3-6) {{webarchive |url=https://web.archive.org/web/20061027174015/http://www.iupac.org/reports/provisional/abstract04/connelly_310804.html |date=October 27, 2006 }}</ref><ref name=transactinides>{{cite book |editor1-first=Lester R. |editor1-last=Morss |editor2-first=Norman M. |editor2-last=Edelstein |editor3-first=Jean |editor3-last=Fuger |title=The Chemistry of the Actinide and Transactinide Elements |edition=3rd |year=2006 |publisher=Springer |location=Dordrecht, The Netherlands |isbn=978-1-4020-3555-5}}</ref>

By definition, transactinide elements are also [[Physics:Transuranium element|transuranic element]]s, i.e. have an atomic number greater than [[Chemistry:Uranium|uranium]] (92).

The transactinide elements all have electrons in the 6d subshell in their ground state. Except for [[Chemistry:Rutherfordium|rutherfordium]] and [[Chemistry:Dubnium|dubnium]], even the longest-lasting isotopes of transactinide elements have extremely short [[Physics:Half-life|half-lives]], measured in seconds, or smaller units. The [[Chemistry:Transfermium Wars|element naming controversy]] involved the first five or six transactinide elements. These elements thus used [[Chemistry:Systematic element name|systematic names]] for many years after their discovery had been confirmed. (Usually the systematic names are replaced with permanent names proposed by the discoverers relatively shortly after a discovery has been confirmed.)

Transactinides are [[Physics:Radioactive decay|radioactive]] and have only been obtained synthetically in laboratories. None of these elements has ever been collected in a macroscopic sample. Transactinide elements are all named after physicists and chemists or important locations involved in the synthesis of the elements.

IUPAC defines an element to exist if its lifetime is longer than 10<sup>−14</sup> seconds, which is the time it takes for the nucleus to form an electron cloud.<ref>[http://www.kernchemie.de/Transactinides/Transactinide-2/transactinide-2.html Kernchemie<!-- Bot generated title -->]</ref>

==List of the known transactinide elements==
[[File:Super heavy elements (polyatomic).svg|right|300px]]
*104 [[Chemistry:Rutherfordium|Rutherfordium]], Rf
*105 [[Chemistry:Dubnium|Dubnium]], Db
*106 [[Chemistry:Seaborgium|Seaborgium]], Sg
*107 [[Chemistry:Bohrium|Bohrium]], Bh
*108 [[Chemistry:Hassium|Hassium]], Hs
*109 [[Chemistry:Meitnerium|Meitnerium]], Mt
*110 [[Chemistry:Darmstadtium|Darmstadtium]], Ds
*111 [[Chemistry:Roentgenium|Roentgenium]], Rg
*112 [[Chemistry:Copernicium|Copernicium]], Cn
*113 [[Chemistry:Nihonium|Nihonium]], Nh
*114 [[Chemistry:Flerovium|Flerovium]], Fl
*115 [[Chemistry:Moscovium|Moscovium]], Mc
*116 [[Chemistry:Livermorium|Livermorium]], Lv
*117 [[Chemistry:Tennessine|Tennessine]], Ts
*118 [[Chemistry:Oganesson|Oganesson]], Og

Work performed from 1964 to 2013 at four laboratories – the [[Organization:Lawrence Berkeley National Laboratory|Lawrence Berkeley National Laboratory]] in the USA, the [[Organization:Joint Institute for Nuclear Research|Joint Institute for Nuclear Research]] in the USSR (later Russia), the [[Organization:GSI Helmholtz Centre for Heavy Ion Research|GSI Helmholtz Centre for Heavy Ion Research]] in Germany, and RIKEN in Japan – identified and confirmed the elements from rutherfordium to oganesson according to the criteria of the IUPAC–IUPAP Transfermium Working Group and subsequent Joint Working Parties. These discoveries complete the seventh row of the periodic table.

The remaining two transactinides, [[Chemistry:Ununennium|ununennium]] (element 119) and [[Chemistry:Unbinilium|unbinilium]] (element 120), have not yet been synthesized: they would begin an eighth period.

== Characteristics ==
Due to their short half-lives (for example, the most stable isotope of rutherfordium has a half-life of 11 minutes, and half-lives decrease gradually going to the right of the group) and the low yield of the nuclear reactions that produce them, new methods have had to be created to determine their gas-phase and solution chemistry based on very small samples of a few atoms each. [[Chemistry:Relativistic quantum chemistry|Relativistic effects]] become very important in this region of the periodic table, causing the filled 7s orbitals, empty 7p orbitals, and filling 6d orbitals to all contract inwards toward the atomic nucleus. This causes a relativistic stabilization of the 7s electrons and makes the 7p orbitals accessible in low excitation states.<ref name=transactinides/>

Elements 104 to 112, rutherfordium through copernicium, form the 6d series of transition elements: for elements 104–108 and 112, experimental evidence shows them to behave as expected for their position in the periodic table. They are expected to have [[Chemistry:Ionic radius|ionic radii]] between those of their 5d transition metal homologs and their [[Chemistry:Actinide|actinide]] pseudohomologs: for example, Rf<sup>4+</sup> is calculated to have ionic radius 76&nbsp;[[Picometre|pm]], between the values for [[Chemistry:Hafnium|Hf]]<sup>4+</sup> (71&nbsp;pm) and [[Chemistry:Thorium|Th]]<sup>4+</sup> (94&nbsp;pm). Their ions should also be less [[Physics:Polarizability|polarizable]] than those of their 5d homologs. Relativistic effects are expected to reach a maximum at the end of this series, at roentgenium (element 111) and copernicium (element 112). Nevertheless, many important properties of the transactinides are still not yet known experimentally, though theoretical calculations have been performed.<ref name=transactinides/>

Elements 113 to 118, nihonium through oganesson, should form a 7p series, completing the [[Chemistry:Period 7 element|seventh period]] in the periodic table. Their chemistry will be greatly influenced by the very strong relativistic stabilization of the 7s electrons and a strong [[Physics:Spin-orbit coupling|spin-orbit coupling]] effect "tearing" the 7p subshell apart into two sections, one more stabilized (7p<sub>1/2</sub>, holding two electrons) and one more destabilized (7p<sub>3/2</sub>, holding four electrons). Additionally, the 6d electrons are still destabilized in this region and hence may be able to contribute some transition metal character to the first few 7p elements. Lower oxidation states should be stabilized here, continuing group trends, as both the 7s and 7p<sub>1/2</sub> electrons exhibit the [[Physics:Inert pair effect|inert pair effect]]. These elements are expected to largely continue to follow group trends, though with relativistic effects playing an increasingly larger role. In particular, the large 7p splitting results in an effective shell closure at flerovium (element 114) and a hence much higher than expected chemical activity for oganesson (element 118).<ref name=transactinides/>

Element 118 is the last element that has been claimed to have been synthesized. The next two elements, [[Chemistry:Ununennium|elements 119]] and [[Chemistry:Unbinilium|120]], should form an 8s series and be an [[Chemistry:Alkali metal|alkali]] and [[Chemistry:Alkaline earth metal|alkaline earth metal]] respectively. The 8s electrons are expected to be relativistically stabilized, so that the trend towards higher reactivity down these groups will reverse direction and the elements will behave more like their period 5 homologs, [[Chemistry:Rubidium|rubidium]] and [[Chemistry:Strontium|strontium]]. Nevertheless, the 7p<sub>3/2</sub> orbital is still relativistically destabilized, potentially giving these elements larger ionic radii and perhaps even being able to participate chemically. In this region, the 8p electrons are also relativistically stabilized, resulting in a ground-state 8s<sup>2</sup>8p<sup>1</sup> valence electron configuration for element 121. Large changes are expected to occur in the subshell structure in going from element 120 to element 121: for example, the radius of the 5g orbitals should drop drastically, from 25&nbsp;Bohr units in element 120 in the excited [Og]5g<sup>1</sup>8s<sup>1</sup> configuration to 0.8&nbsp;Bohr units in element 121 in the excited [Og]5g<sup>1</sup>7d<sup>1</sup>8s<sup>1</sup> configuration, in a phenomenon called "radial collapse" that occurs at element 125. Element 122 should add a further 7d electron to element 121's electron configuration. Elements 121 and 122 should be homologs of [[Chemistry:Actinium|actinium]] and [[Chemistry:Thorium|thorium]], respectively.<ref name=transactinides/>

Beyond element 121, the superactinide series is expected to begin, when the 8s electrons and the filling 8p<sub>1/2</sub>, 7d<sub>3/2</sub>, 6f<sub>5/2</sub>, and 5g<sub>7/2</sub> subshells determine the chemistry of these elements. Complete and accurate CCSD calculations are not available for elements beyond 122 because of the extreme complexity of the situation: the 5g, 6f, and 7d orbitals should have about the same energy level, and in the region of element 160 the 9s, 8p<sub>3/2</sub>, and 9p<sub>1/2</sub> orbitals should also be about equal in energy. This will cause the electron shells to mix so that the [[Chemistry:Block (periodic table)|block]] concept no longer applies very well, and will also result in novel chemical properties that will make positioning these elements in a periodic table very difficult. For example, element 164 is expected to mix characteristics of the elements of [[Chemistry:Group 10 element|group 10]], [[Chemistry:Group 12 element|12]], and [[Chemistry:Noble gas|18]].<ref name=transactinides/>

== See also ==
* [[Physics:Transuranium element|Transuranium element]]
* [[Physics:Bose–Einstein condensate|Bose–Einstein condensate]] (also known as ''Superatom'')
* [[Physics:Island of stability|Island of stability]]

== References ==
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[[Category:Nuclear physics]]
[[Category:Sets of chemical elements]]

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