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Tennessine

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Tennessine, 117Ts
Tennessine
Pronunciation/ˈtɛnəsiːn/[1] ​(TEN-ə-seen)
Appearancesemimetallic (predicted)[2]
Mass number[294]
Tennessine in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
At
↑
Ts
↓
—
livermorium ← tennessine → oganesson
Atomic number (Z)117
Groupgroup 17 (halogens)
Periodperiod 7
Block  p-block
Electron configuration[Rn] 5f14 6d10 7s2 7p5 (predicted)[3]
Electrons per shell2, 8, 18, 32, 32, 18, 7 (predicted)
Physical properties
Phase at STPsolid (predicted)[3][4]
Melting point623–823 K ​(350–550 °C, ​662–1022 °F) (predicted)[3]
Boiling point883 K ​(610 °C, ​1130 °F) (predicted)[3]
Density (near r.t.)7.1–7.3 g/cm3 (extrapolated)[4]
Atomic properties
Oxidation states(−1), (+1), (+3), (+5) (predicted)[2][3]
Ionization energies
  • 1st: 742.9 kJ/mol (predicted)[5]
  • 2nd: 1435.4 kJ/mol (predicted)[5]
  • 3rd: 2161.9 kJ/mol (predicted)[5]
  • (more)
Atomic radiusempirical: 138 pm (predicted)[4]
Covalent radius156–157 pm (extrapolated)[4]
Other properties
Natural occurrencesynthetic
CAS Number54101-14-3
History
Namingafter Tennessee region
DiscoveryJoint Institute for Nuclear Research, Lawrence Livermore National Laboratory, Vanderbilt University and Oak Ridge National Laboratory (2010)
Isotopes of tennessine
Main isotopes[6] Decay
abun­dance half-life (t1/2) mode pro­duct
293Ts synth 25 ms[6][7] α 289Mc
294Ts synth 51 ms[8] α 290Mc
 Category: Tennessine
| references

Ununseptium is the temporary name of a superheavy artificial chemical element with temporary symbol Uus and atomic number 117. The element, also known as eka-astatine or simply element 117, is the second heaviest element of all created. Its discovery was first announced in 2010, when the element was claimed to have been created in Dubna by a joint Russian–American collaboration.[9] Another experiment in 2011 created one of its daughters using a different method, partially proving the results of the discovery experiment, and the original experiment was repeated successfully in 2012. The International Union of Pure and Applied Chemistry (IUPAC), however has made no comment on whether the element can be recognized as discovered or not.

In the periodic table ununseptium is located in the group 17, all previous members of which are halogens. The element is unlikely to be a halogen, however, and will probably show differences, although a few key properties such melting and boiling points and first ionization are expected to follow the periodic trends. While lighter isotopes are agreed in the literature to be very unstable, there are signs that the super-heavy isotopes may be much more stable.

History

Pre-discovery

In 2004 the Joint Institute for Nuclear Research (JINR) team in Dubna, Moscow Oblast, Russia developed a project for the discovery of element 117 (with 117 protons in its nucleus) that required smashing together a berkelium (element 97) target and a calcium (element 20) beam.[10] Citing a lack of production of the exotic material, however, the world's only producer of berkelium, the team at the Oak Ridge National Laboratory in the United States, refused to provide any.[10] Plans to synthesize element 117 were shelved temporarily in favor of the synthesis of element 118, which was produced by smashing another target (made of californium) with calcium in a Russian–American collaboration.[11] The Russian team's desire to use an element they could not access was due to the nature of the calcium beam: the isotope of calcium used in the beam, calcium-48, has 20 protons and 28 neutrons. The difference of 8 between the two kinds of nucleons is extremely rare for stable and near-stable atoms: calcium-48 is the lightest stable nucleus with such a difference, while zinc-68 is the second-lightest.[12] The beam is made in Russia by chemically[13] extracting the minor quantities of calcium-48 present in Earth's natural calcium from the remaining natural calcium.[14] Thus the resulting nuclei become heavier and closer to the sought-after island of stability, a concept wherein some super-heavy atoms can be relatively stable. Sufficiently heavy-enough nuclei have not been created as of 2012, however, and, in a table of nuclides, they are usually shown to the left to the "island" rather than on it.[15]

In 2008 the Americans re-launched a program of berkelium production and the JINR team was contacted.[10] The 22.2-milligram target was purified and then traveled to Dimitrovgrad, Ulyanovsk Oblast to be fixed on a thin titanium firm. It was then transferred to Dubna where it was installed into the JINR particle accelerator, the world's best for the synthesis of superheavy elements (SHEs).[16]

Discovery

Decay chain of the ununseptium isotopes produced. The black figures are experimentally obtained while the blue ones are theoretically predicted.[17]

The experiment began in June 2009 and, in January 2010, scientists at the Flerov Laboratory of Nuclear Reactions announced internally that they had succeeded in detecting the decay of a new element with Z = 117 via two decay chains of an odd-odd isotope (undergoing 6 alpha decays before undergoing a spontaneous fission) and of an odd-even one (3 alpha decays before fission).[9] On April 9, 2010 an official report was released in the journal Physical Review Letters. It revealed that the isotopes mentioned in the previous chains referred to 294Uus and 293Uus, formed as follows:[17]

249
97Bk
 + 48
20Ca
 → The element Uus does not exist.* → The element Uus does not exist. + 3 1
0
n
 (1 event)
249
97Bk
 + 48
20Ca
 → The element Uus does not exist.* → The element Uus does not exist. + 4 1
0
n
 (5 events)

Before the synthesis of ununseptium, none of ununseptium's daughter isotopes were known;[17] thus, there was no basis for an IUPAC discovery claim, much less for its recognition. Ununpentium-289, one of ununseptium's daughters, was created in a different way in 2011, yet it matched the claimed decay properties during the discovery.[18] The discoverers did not, however, submit a claim for the discovery of ununseptium when IUPAC was reviewing claims on discoveries of trans-copernicium elements.[19] The Dubna team repeated the experiment in 2012[20] successfully, thus confirming the synthesis of ununseptium and moving one step closer to having the element officially placed on the periodic table.[21]

Naming

Using Mendeleev's nomenclature for unnamed and undiscovered elements, ununseptium should be known as eka-astatine or dvi-iodine. In 1979 IUPAC published recommendations according to which the element was to be called ununseptium (with the corresponding symbol of Uus),[22] a systematic element name as a placeholder, until the discovery of the element is confirmed and a name is decided on. The recommendations are largely ignored among scientists, who call it "element 117," with the symbol of (117) or even simply 117.[23] No official name has yet been suggested for the element. According to current guidelines from IUPAC, the ultimate name for all new elements should end in "-ium", which means the name for ununseptium may end in -ium, not -ine, even if ununseptium turns out to be a halogen, which traditionally have names ending in "-ine".[24]

Predicted properties

Nucleus stability and isotopes

A 3D graph of stability of elements vs. number of protons Z and neutrons N, showing a "mountain chain" running diagonally through the graph from the low to high numbers, as well as an "island of stability" at high N and Z.
The recent ununseptium synthesis may be thought of as proof of the existence of the magic "island of stability", according to the discoverers.[25]
Main article: Isotopes of ununseptium
See also: Island of stability

The stability of nuclei decreases greatly with the increase in atomic number after plutonium, the heaviest primordial element, so that all isotopes with an atomic number above 101 decay radioactively with a half-life under a day, with an exception of dubnium-268. No elements with atomic numbers above 82 (after lead) have stable isotopes.[26] Nevertheless, because of reasons not very well understood yet, there is a slight increased nuclear stability around atomic numbers 110–114, which leads to the appearance of what is known in nuclear physics as the "island of stability". This concept, proposed by University of California professor Glenn Seaborg, explains why superheavy elements last longer than predicted.[27] Ununseptium is the second heaviest element of all created so far and is radioactive, having a half-life that appears to be less than one second. Nonetheless, this is still longer than the predicted values used in the discovery report.[17] The Dubna team believes that the synthesis of the element is direct experimental proof of the existence of the island.[25]

Calculations using a quantum-tunneling model predict the existence of several isotopes of ununseptium with alpha-decay half-lives up to over 10 ms, culminating at 296Uus (the research ends on 303Uus).[28] A more detailed study by the Brazilian Center for Physics Research (CBPF) on the element's isotopes shows similar results (in particular that 296Uus is the most stable isotope in its region),[a] but goes further up to 337Uus. In the region neighboring the synthesized isotopes 293Uus and 294Uus, some isotopes could be slightly more stable than the two that are known, most likely 295Uus and 296Uus. It reveals a general increasing stability trend for isotopes heavier than 301Uus, the isotope that has 184 neutrons, considered to be a magic number in physics that is thought to provide extra stability. Beginning with 310Uus, the isotopes again begin to be more stable than the synthesized two; 326Uus has a half-life of over 300 years and the heaviest isotope for which predictions are available, 337Uus, should have a half-life of about 1016 years.[29][b]

Predicted atomic, physical, and chemical properties

Ununseptium is a member of group 17 in the periodic table, below the five halogens. The previous members of the group commonly accept another electron to achieve an stable noble-gas electronic configuration, which is the minimum-energy configuration in which the outer electrons are tightly bound.[31] A neutral halogen atom, however, lacks the extra electron, having a valence electron configuration of ns2np5; in ununseptium's case, the valence electron configuration is predicted to be 7s27p5.[3] Certain chemical properties, however, are predicted to differ from what one would expect based on periodic trends from the lighter halogens because of relativistic effects.

In its free form the element is thought to form diatomic molecules, just like the other halogens. Since the sigma bonding shows a great antibonding character in the At2 molecule, ununseptium is predicted to continue the trend and a strong pi character should be seen in the bonding of Uus2.[3][32] The resulting molecule could become the heaviest molecule composed of a single element at standard conditions. The melting point of ununseptium is predicted to be 350–500 °C[3] and the boiling point should be about 550 °C,[3] exceeding the astatine (and all preceding) values, following periodic trends, which means that the element should be a solid in its free form. The first ionization energy (7.7 eV) is lower than that of the previous halogens, again following the trend.[3]

Achieving the octet configuration by forming a negative oxidation state, however, becomes less common going down the group, with astatine already forming a positive oxidation state in its hydride. This trend continues for ununseptium: the −1 state is predicted to be the least stable of the predicted four, with +5, +3, and especially +1 being more stable because of the destabilization of the three outermost 7p3/2 electrons. The +5 state is predicted to also be uncommon, as the 7p1/2 electrons are (oppositely) stabilized. The +3 state may resemble that of Au3+ in ion-exchange behavior in a halide environment.[3]

Similar to Uus2, the molecule UusCl should be bonded via a single pi bond.[32] The molecule UusF should be the most tightly bound of all interhalogen monofluorides.[32] The halogen hydrides show an increase in bond length and a decrease in dissociation energy; the molecule UusH is thought to continue the trend.[3] The molecule UusF3 should not have the T-shaped geometry seen in other interhalogen trifluorides.[32] In the molecule UutUus, the more electronegative atom is notably predicted to be the ununtrium atom, the opposite of what periodic trends would predict.[32]

See also

Notes

  1. ^ This research gives the total half-lives, not just the alpha-decay half-lives.
  2. ^ Half-lives of the six heaviest isotopes studied in the report, 332Uus through 337Uus, were predicted by the report to exceed 80 million years,[29] the half-life of 244Pu,[30] the least stable primordial nuclide; thus, if ever created in sufficient quantity, these isotopes could have survived until the present day.

References

  1. ^ Ritter, Malcolm (June 9, 2016). "Periodic table elements named for Moscow, Japan, Tennessee". Associated Press. Retrieved December 19, 2017.
  2. ^ a b Fricke, Burkhard (1975). "Superheavy elements: a prediction of their chemical and physical properties". Recent Impact of Physics on Inorganic Chemistry. Structure and Bonding. 21: 89–144. doi:10.1007/BFb0116498. ISBN 978-3-540-07109-9. Retrieved 4 October 2013.
  3. ^ a b c d e f g h i j k l Hoffman, Darleane C.; Lee, Diana M.; Pershina, Valeria (2006). "Transactinides and the future elements". In Morss; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands: Springer Science+Business Media. ISBN 978-1-4020-3555-5.
  4. ^ a b c d Bonchev, D.; Kamenska, V. (1981). "Predicting the Properties of the 113–120 Transactinide Elements". Journal of Physical Chemistry. 85 (9): 1177–1186. doi:10.1021/j150609a021.
  5. ^ a b c Chang, Zhiwei; Li, Jiguang; Dong, Chenzhong (2010). "Ionization Potentials, Electron Affinities, Resonance Excitation Energies, Oscillator Strengths, And Ionic Radii of Element Uus (Z = 117) and Astatine". J. Phys. Chem. A. 2010 (114): 13388–94. Bibcode:2010JPCA..11413388C. doi:10.1021/jp107411s.
  6. ^ a b Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  7. ^ Khuyagbaatar, J.; Yakushev, A.; Düllmann, Ch. E.; et al. (2014). "48Ca+249Bk Fusion Reaction Leading to Element Z=117: Long-Lived α-Decaying 270Db and Discovery of 266Lr". Physical Review Letters. 112 (17): 172501. Bibcode:2014PhRvL.112q2501K. doi:10.1103/PhysRevLett.112.172501. PMID 24836239.
  8. ^ Oganessian, Yu. Ts.; et al. (2013). "Experimental studies of the 249Bk + 48Ca reaction including decay properties and excitation function for isotopes of element 117, and discovery of the new isotope 277Mt". Physical Review C. 87 (5): 054621. Bibcode:2013PhRvC..87e4621O. doi:10.1103/PhysRevC.87.054621.
  9. ^ a b Recommendations: 31st meeting, PAC for Nuclear Physics
  10. ^ a b c Gabage, Bill (2010). "Synthesis of a new element with atomic number Z=117". webelements.com.
  11. ^ Oganessian, Yu. Ts.; et al. (2002). "Results from the first 249Cf+48Ca experiment" (PDF). JINR Communication. JINR, Dubna. {{cite journal}}: Explicit use of et al. in: |author= (help)
  12. ^ G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. ^ Jepson, B. E.; Shockley, G. C. (1984). "Calcium hydroxide isotope effect in calcium isotope enrichment by ion exchange". Separation Science and Technology. 19 (2–3): 173–181. Retrieved 2012-07-07. {{cite journal}}: Cite has empty unknown parameter: |1= (help)
  14. ^ "Ununseptium – the 117th element". RIA Novosti. 2009-10-28. Retrieved 2012-07-07.
  15. ^ "Universal Nuclide Chart". Nucleonica. Institute for Transuranium Elements. 2007–2012. Retrieved 2012-07-03.
  16. ^ Lauren Schenkman (2010). "Discovery of 'Missing' Element 117 Hints at Stable Isotopes to Come". Ukrainian Science Club. Retrieved 2012-06-28.
  17. ^ a b c d Yu. Ts. Oganessian; et al. (2010). "Synthesis of a New Element with Atomic Number Z=117". Phys. Rev. Lett. (104). {{cite journal}}: Explicit use of et al. in: |author= (help); Text "10.1103/PhysRevLett.104.142502" ignored (help)
  18. ^ Template:Ru icon "В лабораториях ОИЯИ. Возвращение к дубнию". JINR. 2011. {{cite web}}: Unknown parameter |trans_title= ignored (|trans-title= suggested) (help)
  19. ^ Barber, Robert C.; Karol, Paul J.; Nakahara, Hiromichi; Vardaci, Emanuele; Vogt, Erich W. (2011). "Discovery of the elements with atomic numbers greater than or equal to 113 (IUPAC Technical Report)". Pure and Applied Chemistry: 1. doi:10.1351/PAC-REP-10-05-01.
  20. ^ Template:Ru icon "Эксперимент по синтезу 117-го элемента получает продолжение". JINR. 2012. {{cite web}}: Unknown parameter |trans_title= ignored (|trans-title= suggested) (help)
  21. ^ "Russian Scientists Confirm 117th Element". RIA Novosti. 2012-06-25. Retrieved 2012-07-05.
  22. ^ Chatt, J. (1979). "Recommendations for the Naming of Elements of Atomic Numbers Greater than 100". Pure Appl. Chem. 51 (2): 381–384. doi:10.1351/pac197951020381.
  23. ^ Folden, Cody (2009-01-31). "The Heaviest Elements in the Universe" (PDF). Saturday Morning Physics at Texas A&M. Retrieved 2012-03-09.
  24. ^ Koppenol, W. H. (2002). "Naming of new elements (IUPAC Recommendations 2002)" (PDF). Pure and Applied Chemistry. 74 (5): 787. doi:10.1351/pac200274050787.
  25. ^ a b Template:Ru icon "Синтез нового 117-го элемента". JINR. 2010. {{cite web}}: Unknown parameter |trans_title= ignored (|trans-title= suggested) (help)
  26. ^ Marcillac, Pierre de (2003). "Experimental detection of α-particles from the radioactive decay of natural bismuth". Nature. 422 (6934): 876–878. Bibcode:2003Natur.422..876D. doi:10.1038/nature01541. PMID 12712201. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  27. ^ Kulik, Glenn D. (2002). Van Nostrand's scientific encyclopedia (9 ed.). Wiley-Interscience. ISBN 978-0-471-33230-5. OCLC 223349096. {{cite book}}: |first2= missing |last2= (help); More than one of |last1= and |last= specified (help)
  28. ^ Chowdhury, Roy P.; Samanta, C.; Basu, D. N. (2008). "Search for long lived heaviest nuclei beyond the valley of stability". Physical Reviews C. 77 (4): 044603. Bibcode:2008PhRvC..77d4603C. doi:10.1103/PhysRevC.77.044603.
  29. ^ a b Duarte, S. B.; et al. (2004). Half-life prediction for decay modes for superheavy nuclei (Report). Centro Brasiliero de Pesquisas Físicas. ISSN 0029-3865. {{cite report}}: Explicit use of et al. in: |author= (help)
  30. ^ G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  31. ^ Bader, Richard F.W. "An Introduction to the Electronic Structure of Atoms and Molecules". McMaster University. Retrieved 2008-01-18.
  32. ^ a b c d e Leszczynski, J. (2010). Relativisic Methods for Chemists. Springer Science+Business Media. pp. 84, 504. doi:10.1007/9781402099755. ISBN 9781402099748.
  • Reid, Tim (2007). "Superheavy elements: Finding the right ingredients". Nature China. doi:10.1038/nchina.2007.186.
  • Eric Scerri, The Periodic Table, Its Story and Its Significance, Oxford University Press, 2007
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