Technetium: Difference between revisions - Wikipedia


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'''Technetium''' is a [[chemical element]]; it has [[Symbol (chemistry)|symbol]] '''Tc''' and [[atomic number]] 43. It is the lightest element whose [[isotopes]] are all [[radioactive]]. Technetium and [[promethium]] are the only radioactive elements whose neighbours in the sense of atomic number are both stable. All available technetium is produced as a [[synthetic element]]. Naturally occurring technetium is a spontaneous [[fission product]] in [[uranium ore]] and [[thorium]] ore (the most common source), or the product of [[neutron capture]] in [[molybdenum]] ores. This silvery gray, crystalline [[transition metal]] lies between [[manganese]] and [[rhenium]] in [[group 7 element|group 7]] of the [[periodic table]], and its chemical properties are intermediate between those of both adjacent elements. The most common naturally occurring isotope is <sup>99</sup>Tc, in traces only.

Many of technetium's properties had been predicted by [[Dmitri Mendeleev]] before it was discovered. Mendeleev noted a gap in his periodic table and gave the undiscovered element the provisional name ''[[Mendeleev's predicted elements|ekamanganese]]'' (''Em''). In 1937, technetium (specifically the [[technetium-9798]] isotope) became the first predominantly artificial element to be produced, hence its name (from the Greek {{lang|el|τεχνητός}}, '' technetos'', from ''techne'', as in "craft", "art" and having the meaning of "artificial", + {{nowrap|''[[wikt:-ium#Suffix|-ium]]'').}}

One short-lived [[gamma ray]]-emitting [[nuclear isomer]], [[technetium-99m]], is used in [[nuclear medicine]] for a wide variety of tests, such as bone cancer diagnoses. The ground state of the [[nuclide]] [[technetium-99]] is used as a gamma-ray-free source of [[beta particle]]s. Long-lived [[isotopes of technetium|technetium isotopes]] produced commercially are byproducts of the [[nuclear fission|fission]] of [[uranium-235]] in [[nuclear reactors]] and are extracted from [[nuclear fuel cycle|nuclear fuel rods]]. Because even the longest-lived isotope of technetium has a relatively short [[half-life]] (4.21&nbsp;million years), the 1952 detection of technetium in [[red giant]]s helped to prove that stars can [[nuclear fusion|produce heavier elements]].