technetium teknetium (#) Fr.: technétium A radioactive chemical element which does not exist naturally on Earth; symbol Tc. Atomic number 43; mass number of most stable isotope 98; melting point 2,200°C; boiling point 4,877°C. Technetium is synthesised via the → s-process in deep layers of → asymptotic giant branch stars. From the Gk. technetos "artificial," initially called masurium. |