Tennessine (formerly Ununseptium) is a radioactive superheavy man-made chemical element. It has a symbol Ts and atomic number of 117. It is the second heaviest element of all, and is the second to last element. It is in group 17 in the periodic table, where the halogens are. Its properties are not yet fully known but it is probably a metalloid. The discovery of tennessine was announced in 2010 by scientists in Russia and the United States. They collaborated and it is the most recently discovered element as of 2019. It is named after the state of Tennessee and it has no uses except research.
|Tennessine in the periodic table|
|Atomic number (Z)||117|
|Group||group 17 (halogens)|
|Element categories||, but probably a post-transition metal|
|Electron configuration||[Rn] 5f14 6d10 7s2 7p5 (predicted) (predicted)|
|Electrons per shell||2, 8, 18, 32, 32, 18, 7 (predicted)|
|Phase at STP||solid (predicted)|
|Melting point||623–823 K (350–550 °C, 662–1022 °F) (predicted)|
|Boiling point||883 K (610 °C, 1130 °F) (predicted)|
|Density (near r.t.)||7.1–7.3 g/cm3 (extrapolated)|
|Oxidation states||(−1), (+1), (+3), (+5) (predicted)|
|Atomic radius||empirical: 138 pm (predicted)|
|Covalent radius||156–157 pm (extrapolated)|
|Naming||after Tennessee region|
|Discovery||Joint Institute for Nuclear Research, Lawrence Livermore National Laboratory, Vanderbilt University and Oak Ridge National Laboratory (2009)|
|Main isotopes of tennessine|
In 2004, the Joint Institute for Nuclear Research (JINR) team in Dubna, Moscow Oblast, Russia planned an experiment to synthesize (create) element 117. It is called element 117 because the number of protons in its atom is 117. To do this, they needed to fuse the elements berkelium (element 97) and calcium (element 20). However, the American team at Oak Ridge National Laboratory, the only producer of berkelium in the world, had stopped making berkelium for a while. So, they synthesized the element 118 first using californium (element 98) and calcium.
The Russian team wanted to use berkelium because the isotope of calcium used in the experiment, calcium-48, has 20 protons and 28 neutrons. This is the lightest stable or almost stable nucleus (the middle part of an atom) with much more neutron than proton. Zinc-68 is the second-lightest nucleus of this kind, but it is heavier than calcium-48. Since tennessine has 117 protons, they need another atom with 97 protons to be combined with the calcium atom, and berkelium has 97 protons.
In the experiment, the berkelium is made into a target and the calcium is fired in the form of a beam to the berkelium target. The calcium beam is created in Russia by removing the small amount of calcium-48 from natural calcium using chemical means. The nuclei that is made after the experiment will be heavier and is nearer to the island of stability. This is the idea that some very heavy atoms can be quite stable.
Discovery of TennessineEdit
In 2008, the American team started again to create berkelium, and they told the Russian team about it. The program made 22 milligrams of berkelium, and this is enough for the experiment. Soon after, the berkelium was cooled in 90 days and was made more pure by chemical means in 90 more days. The berkelium target had to be taken to Russia quickly because the half-life of the isotope of berkelium used, berkelium-249, is only 330 days. In other words, after 330 days, half of all the berkelium will no longer be berkelium. Actually, if the experiment did not start six months after the target was made, it would have been cancelled because they did not have enough berkelium for the experiment. In summer 2009, the target was packed into five lead containers and was sent by a commercial flight from New York to Moscow.
Both teams had to face the bureaucratic obstacle between America and Russia before they send the berkelium target to allow it to arrive in Russia on time. However, there were still problems: Russian customs did not let the berkelium target get into the country twice due to missing or incomplete paperwork. Even though the target went over the Atlantic Ocean five times, the whole journey only took a few days. When the target finally got into Moscow, it was sent to Dimitrovgrad, Ulyanovsk Oblask. Here, the target was placed on a thin titanium film (layer). This film was then sent to Dubna where it was placed inside the JINR particle accelerator. This particle accelerator is the most powerful particle accelerator in the world for the creation of superheavy elements.
The experiment began in June 2009. In January 2010, the scientists at the Flerov Laboratory of Nuclear Reactions announced within the laboratory that they had found the decay of a new element with atomic number 117 through two decay chains. The odd-odd isotope does 6 alpha decays before doing a spontaneous (sudden) fission. The odd-even isotope does 3 alpha decays before fission. On 9 April 2010, an official report was released in the Physical Review Letters journal. It showed that the isotopes that were mentioned in the decay chains were 294Ts and 293Ts. The isotopes were made as follows:
- Ritter, Malcolm (9 June 2016). "Periodic table elements named for Moscow, Japan, Tennessee". Associated Press. Retrieved 19 December 2017.
- Fricke, B. (1975). "Superheavy elements: a prediction of their chemical and physical properties". Recent Impact of Physics on Inorganic Chemistry. 21: 89–144. doi:10.1007/BFb0116498. Retrieved 4 October 2013.
Royal Society of Chemistry (2016). "Tennessine". rsc.org. Royal Society of Chemistry. Retrieved 9 November 2016.
A highly radioactive metal, of which only a few atoms have ever been made.
GSI (14 December 2015). "Research Program – Highlights". superheavies.de. GSI. Retrieved 9 November 2016.
If this trend were followed, element 117 would likely be a rather volatile metal. Fully relativistic calculations agree with this expectation, however, they are in need of experimental confirmation.
- 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.
- 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.
- 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.
- 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.
- 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.
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