What are the properties of technetium-99?
Technetium-99 is silver-gray, radioactive metal. It occurs naturally only in very small amounts. Its melting point is 3,942 °F and its boiling point is 8,811 °F. It is also a very dense material–at room temperature, a mass of technetium-99 weighs 11.5 times as much as an equal volume of water. Technetium-99 has a radioactive half-life of 212,000 years. Technetium-99m (called metastable Tc-99) has a half-life of only about 6 hours and decays to Tc-99 primarily by gamma emission. Technetium-99 decays to form ruthenium-99, which is stable, by emitting beta and gamma radiation. Technetium exhibits the complex chemistry of a transition metal. It dissolves in nitric acid, aqua regia, and hot concentrated sulfuric acid, but is insoluble in hydrochloric acid.
