Tennessine | |||||||||||||||||||||
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Pronunciation | /ˈtɛnəsiːn/[1] | ||||||||||||||||||||
Appearance | semimetallic (predicted)[2] | ||||||||||||||||||||
Mass number | [294] (data not decisive)[a] | ||||||||||||||||||||
Tennessine in the periodic table | |||||||||||||||||||||
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Atomic number (Z) | 117 | ||||||||||||||||||||
Group | group 17 (halogens) | ||||||||||||||||||||
Period | period 7 | ||||||||||||||||||||
Block | p-block | ||||||||||||||||||||
Electron configuration | [Rn] 5f14 6d10 7s2 7p5 (predicted)[4] | ||||||||||||||||||||
Electrons per shell | 2, 8, 18, 32, 32, 18, 7 (predicted) | ||||||||||||||||||||
Physical properties | |||||||||||||||||||||
Phase at STP | solid (predicted)[4][5] | ||||||||||||||||||||
Melting point | 623–823 K (350–550 °C, 662–1022 °F) (predicted)[4] | ||||||||||||||||||||
Boiling point | 883 K (610 °C, 1130 °F) (predicted)[4] | ||||||||||||||||||||
Density (near r.t.) | 7.1–7.3 g/cm3 (extrapolated)[5] | ||||||||||||||||||||
Atomic properties | |||||||||||||||||||||
Oxidation states | common: (none) (−1), (+5) | ||||||||||||||||||||
Ionization energies | |||||||||||||||||||||
Atomic radius | empirical: 138 pm (predicted)[5] | ||||||||||||||||||||
Covalent radius | 156–157 pm (extrapolated)[5] | ||||||||||||||||||||
Other properties | |||||||||||||||||||||
Natural occurrence | synthetic | ||||||||||||||||||||
CAS Number | 54101-14-3 | ||||||||||||||||||||
History | |||||||||||||||||||||
Naming | after Tennessee region | ||||||||||||||||||||
Discovery | Joint Institute for Nuclear Research, Lawrence Livermore National Laboratory, Vanderbilt University and Oak Ridge National Laboratory (2010) | ||||||||||||||||||||
Isotopes of tennessine | |||||||||||||||||||||
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Tennessine is a synthetic chemical element; it has symbol Ts and atomic number 117. It has the second-highest atomic number and joint-highest atomic mass of all known elements and is the penultimate element of the 7th period of the periodic table. It is named after the U.S. state of Tennessee, where key research institutions involved in its discovery are located (however, the IUPAC says that the element is named after the "region of Tennessee").
The discovery of tennessine was officially announced in Dubna, Russia, by a Russian–American collaboration in April 2010, which makes it the most recently discovered element as of 2024[update]. One of its daughter isotopes was created directly in 2011, partially confirming the results of the experiment. The experiment itself was repeated successfully by the same collaboration in 2012 and by a joint German–American team in May 2014. In December 2015, the Joint Working Party of the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP), which evaluates claims of discovery of new elements, recognized the element and assigned the priority to the Russian–American team. In June 2016, the IUPAC published a declaration stating that the discoverers had suggested the name tennessine, a name which was officially adopted in November 2016.[b]
Tennessine may be located in the "island of stability", a concept that explains why some superheavy elements are more stable despite an overall trend of decreasing stability for elements beyond bismuth on the periodic table. The synthesized tennessine atoms have lasted tens and hundreds of milliseconds. In the periodic table, tennessine is expected to be a member of group 17, the halogens.[c] Some of its properties may differ significantly from those of the lighter halogens due to relativistic effects. As a result, tennessine is expected to be a volatile metal that neither forms anions nor achieves high oxidation states. A few key properties, such as its melting and boiling points and its first ionization energy, are nevertheless expected to follow the periodic trends of the halogens.
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