Technetium is a silvery gray, radioactive transition metal with a melting point of 2157 degrees Celsius. It has a half-life of 211000 years. Its oxidation states range from -3 to +7 with +4, +5, and +7 being the most common. It was first identified in 1937 by the Italian scientists Carlo Perrier and Emilio Segre found it in irradiated Molybdenum foil. Technetium used to be formed naturally in the natural nuclear reactor beneath Gabon, but it ceased to exist long ago.

Technetium 99m is used for medical imaging to find cancerous tumors within the body.