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| Atomic Number: | 43 | Atomic Symbol: | Tc | | Atomic Weight: | 97 | Electron Configuration: | 2-8-18-14-1 | | Shells: | 2,8,18,14,1 | Filling Orbital: | 4d6 | | Melting Point: | 2200oC | Boiling Point: | 4877oC | | Description: | First artificially created element | | Uses: | Excellent Superconductor below 11oK |
History(Gr. technetos, artificial). Element 43 was predicted on the
basis of the periodic table, and was erroneously reported as having been
discovered in 1925, at which time it was named masurium. The element was
actually discovered by Perrier and Segre in Italy in 1937.
SourcesIt was found in a sample of molybdenum, which was bombarded by
deuterons in the Berkeley cyclotron, and which E. Lawrence sent to these
investigators. Technetium was the first element to be produced artificially.
Since its discovery, searches for the element in terrestrial material have been
made without success. If it does exist, the concentration must be very small.
Technetium has been found in the spectrum of S-, M-, and N-type stars, and its
resence in stellar matter is leading to new theories of the production of heavy
elements in the stars. Nineteen isotopes of technetium, with atomic masses
ranging from 90 to 108, are known. 97Tc has a half-life of 2.6 x 10^6 years.
98Tc has a half-life of 4.2 x 10^6 years. The isomeric isotope 95mTc, with a
half-life of 61 days, is useful for tracer work, as it produces energetic gamma
rays. Technetium metal has been produced in kilogram quantities. The metal was
first prepared by passing hydrogen gas at 1100C over Tc2S7. It is now
conveniently prepared by the reduction of ammonium pertechnetate with hydrogen.
Properties- Technetium is a silvery-gray metal that tarnishes slowly in moist air.
- Until 1960, technetium was available only in small amounts and the price was
as high as $2800/g.
- It is now commercially available to holders of O.R.N.L. permits at a price
of $60/g.
- The chemistry of technetium is said to be similar to that of rhenium.
- Technetium dissolves in nitric acid, aqua regia, and conc. sulfuric acid,
but is not soluble in hydrochloric acid of any strength.
Uses- The metal is an excellent superconductor at 11K and below.
- The element is a remarkable corrosion inhibitor for steel.
- It is reported that mild carbon steels may be effectively protected by as
little as 55 ppm of KTcO4 in aerated distilled water at temperatures up to
250C.
- This corrrosion protection is limited to closed systems, since technetium is
radioative and must be confined.
Handling98Tc has a specific activity of 6.2 x 10^8 Bq/g. Activity of
this level must not be allowed to spread. 99Tc is a contamination hazard and
should be handled in a glove box
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