Specifications: Technetium Technetium is the lightest chemical element with no stable isotope. It is a synthetic element. It has atomic number 43 and is given the symbol Tc. The chemical properties of this silvery grey, crystalline transition metal are intermediate between rhenium and manganese. Its short-lived gamma-emitting nuclear isomer 99mTc (technetium-99m) is used in nuclear medicine for a wide variety of diagnostic tests. 99Tc is used as a gamma ray-free source of beta particles. The pertechnetate ion (TcO4-) could eventually be used[clarify] as a strong anodic corrosion inhibitor for mild steel in closed cooling systems. Before the element was discovered, many of the properties of element 43 were predicted by Dmitri Mendeleev. Mendeleev noted a gap in his periodic table and called the element ekamanganese. In 1937 its isotope 97Tc became the first predominantly artificial element to be produced, hence its name. Most technetium produced on Earth is a by-product of fission of uranium-235 in nuclear reactors and is extracted from nuclear fuel rods. No isotope of technetium has a half-life longer than 4.2 million years (98Tc), so its detection in red giants in 1952 helped bolster the theory that stars can produce heavier elements. On Earth, technetium occurs in trace but measurable quantities as a product of spontaneous fission in uranium ore or by neutron capture in molybdenum ores.
