A radioactive transuranic element that is a p-block transactinide. a.n. 117; mass number of the most stable isotope 294, with a half-life of about 50 ms. There is one other main isotope. Tennessine was discovered in the 2000s in a nuclear reaction between berkelium-249 and calcium-48.

https://www.webelements.com/tennessine/ Information from the WebElements site