Thursday, December 23, 2010

Technetium: Obscurest Subject of the Periodic Kingdom?

Despite of being and having the title of the first artificially produced element, does technetium qualify as the obscurest subject of the “Kingdom” of the Periodic Table of Elements?

By: Ringo Bones

Even though it’s more popular cousin named plutonium has been hogging the geopolitical headlines since the end of World War II as the most famous artificially produced element, it was in fact technetium – atomic number 43, chemical symbol Tc – that was the first artificially produced element back in 1937 – by Emilio Segré and Carl Perrier of Italy. The name technetium is derived from the Greek word technetos meaning artificial. As the first man-made element, it was originally produced by the atomic bombardment of molybdenum.

Technetium’s original preparation back in 1937 was from neutron and deuteron bombardment of molybdenum. In a nuclear reactor, substantial amounts of technetium results from the decay of the molybdenum-99 isotope – a uranium-235 fission product. Beta emission of molybdenum-99 gives technetium-99. This isotope eventually is converted to ruthenium-99. Separation of technetium from uranium is accomplished by converting both to chlorides. Hydrogen peroxide treatment gives uranium oxychloride and hydrogen sulphide action on the remaining solution to which platinum chloride is added gives technetium sulphide and platinum sulphide. The sulfides dissolve in aqueous ammonia in which technetium oxide can be distilled from an acidified solution. The metal is prepared by converting the oxide to ammonium technetate followed by hydrogen reduction.

Later, the element was found among the fission products of uranium. During the mid to late 1960s, technetium sells for around 3,000 US dollars an ounce – while gold during that time sells for about 38 US dollars an ounce. Then and now, the going rate for technetium is probably closer to 100 times the going rate for gold. Currently, technetium and its alloys are used as superconductors. It is also used in radiation therapy and in minute quantities, technetium acts as a corrosion inhibitor for steel.

Technetium also played an important role in astronomy during the discovery by Paul W. Merrill of substantial amounts of technetium in so-called S stars, as shown by their spectroscopic analysis, has been interpreted as a clear evidence of stellar evolution in the relatively recent past due to the 300,000-year half-life of technetium’s longest-lived isotope - which is very short in comparison to the presumed lifespan of the universe. Even though it is – at the moment – languishing in obscurity in comparison to its more famous man-made cousin named plutonium, nevertheless, technetium still has something important to contribute to our 21st Century scientific community.

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