Tennessine – facts and properties
- Symbol
- Ts
- Atomic number
- 117
- Atomic mass
- 294 u
- Period
- 7
- Group
- 17
- Category
- unknown, probably metalloid
- Electron configuration
- [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁵
- Valence electrons
- 7
- State at standard conditions
- expected to be solid
- Discovered
- 2010
Tennessine has atomic number 117 and is the second-heaviest known element. It is artificial and highly radioactive and stands in group 17 below astatine, so it belongs to the halogens. Researchers from Russia and the United States worked together on its discovery: the target material came from Oak Ridge, and the atoms were made at Dubna. Nearly all of its properties are only predicted. The name goes back to the US state of Tennessee.
Position in the periodic table
Occurrence and extraction
Tennessine is not found in nature. No stable isotope of it exists. The longest-lived, tennessine-294, has a half-life of a few tens of milliseconds, and the lighter tennessine-293 decays faster still. Both values rest on few atoms.
In April 2010 a team led from Dubna, with the Oak Ridge National Laboratory, Vanderbilt University in Nashville and the Lawrence Livermore National Laboratory, reported six atoms. They had been made in a hot fusion, as described on the flerovium page, with berkelium-249 as the target and calcium-48 as the projectile. The decay chains led through moscovium and nihonium to further nuclei. In 2012 more atoms followed at Dubna, and in 2014 a group at GSI in Darmstadt confirmed the result independently. At the end of 2015 IUPAC recognised the discovery.
IUPAC fixed the name in 2016. It acknowledges the contribution of the Tennessee region, which includes the Oak Ridge National Laboratory, Vanderbilt University and the University of Tennessee in Knoxville. The ending -ine follows the other halogens, as in astatine.
Properties and reactions
Tennessine is in period 7 and group 17, below astatine, with iodine, bromine, chlorine and fluorine above. The predicted electron configuration is [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁵, giving 7 valence electrons: two in the 7s and five in the 7p orbital. The atomic mass entry, 294 u, is the mass number of tennessine-294. Measured values for melting point, boiling point and density are missing.
The halogens show a clear trend: fluorine and chlorine are gases, bromine is a liquid, iodine and probably astatine are solids, and the metallic character grows. A solid is therefore expected, which according to calculations melts at several hundred degrees Celsius. It should lie between metal and non-metal, closer to a metalloid than to a typical halogen.
Because of the relativistic splitting of the 7p level, two of the five 7p electrons sit deep and tight, three further out. Calculations therefore predict that the state minus one, typical of the halogens, loses importance. Instead the states plus one and plus three are expected, perhaps plus five as well. Whether it forms compounds like a halogen at all is unsettled. No measured chemical properties are known.
Research and synthesis
Tennessine serves basic research only and has no application. Its production depends on a scarce raw material. Berkelium-249 is made in only a few high-flux reactors and in small amounts, so the experiments cannot be repeated at will.
The discovery shows how international the road to the heaviest elements is. The berkelium was produced and chemically separated in the United States. In Dimitrovgrad in Russia it was applied to thin foils before it went to Dubna. There the accelerator and detectors were waiting, and the confirmation came from Germany.
Open questions concern mainly the nuclei. That tennessine-294 lives longer than tennessine-293 fits the expectation that extra neutrons stabilise nuclei. Isotopes with still more neutrons would be important to test how far this trend carries and how near the island of stability lies.
Quick question
What is the atomic number of tennessine (Ts)?
FAQ
What is tennessine named after?
After the US state of Tennessee, where Oak Ridge lies. The ending follows the -ine of the other halogens. IUPAC confirmed the name in 2016.
Is tennessine a halogen?
By its place in group 17, yes. Whether it behaves like a halogen chemically is open, because calculations predict deviations and measurements are missing.
How long does tennessine live?
Its isotopes decay within fractions of a second. The longest-lived known isotope has a half-life of a few tens of milliseconds.