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. 