tennessine

Tennessine is a synthetic chemical element with the symbol Ts and atomic number 117. It is the element at the bottom of group 17 (the halogens) in the seventh period of the periodic table. Tennessine does not occur naturally and has been produced only in extremely small quantities in nuclear laboratories through fusion-evaporation reactions, for example by bombarding berkelium-249 with calcium-48. The name and symbol were officially recognized by IUPAC in 2016, honoring the U.S. state of Tennessee; its provisional name was ununseptium (Uts) prior to this.

As a superheavy, highly radioactive element, tennessine has no stable or long-lived isotopes. The isotopes observed to date have very short half-lives, typically measured in milliseconds to fractions of a second, and all known isotopes decay by alpha emission or spontaneous fission. Because of the extremely short lifetimes and the difficulty of production, detailed experimental information on its chemical properties is limited, and much of the understanding comes from theoretical predictions and extrapolation from lighter halogens.

Predictions suggest that tennessine would share some chemical behavior with other halogens, but relativistic effects at such high atomic numbers are expected to cause notable differences from lighter members of the group. Consequently, its chemistry is not well established experimentally. Theoretical studies anticipate compounds such as fluorides and possible oxides, with a range of oxidation states, though no comprehensive experimental confirmation has been achieved due to the element’s fleeting existence.

Tennessine remains primarily of interest to nuclear and theoretical chemistry, serving as a test case for relativistic quantum effects in heavy elements.