Technetium

Technetium is a chemical element with the symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive; none are stable, excluding the fully ionized state of 97Tc. Nearly all technetium is produced synthetically, and only minute amounts are found in nature. Naturally occurring technetium occurs as a spontaneous fission product in uranium ore or by neutron capture in molybdenum ores. The chemical properties of this silvery gray, crystalline transition metal are intermediate between rhenium and manganese.

History

Technetium was formally discovered in 1937 by Carlo Perrier and Emilio Segrè, who were able to demonstrate that technetium-95 and technetium-97 are produced by the neutron bombardment of molybdenum. This was the first element to be artificially produced, hence its name, from the Greek τεχνητός, meaning "artificial".

Properties and compounds

Technetium exhibits nine oxidation states from −1 to +7, with +4, +5, and +7 being the most common. Technetium dissolves in aqua regia, nitric acid, and concentrated sulfuric acid, but it is not soluble in hydrochloric acid of normal strength. This behavior is similar to that of rhenium and manganese, the elements above and below technetium in the periodic table.

Applications

The most common use of technetium is in medical imaging. Technetium-99m is used in over 20 million diagnostic nuclear medical procedures annually. Other uses of technetium include the production of radioactive tracers and as an industrial gamma ray source.

See also

• List of chemical elements
• Periodic table

References

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