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Author: langbot
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English[en]
Technetium is a chemical element with the symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive. Nearly 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 of the periodic table, and its chemical properties are intermediate between those of both adjacent elements. The most common naturally occurring isotope is 99Tc, 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 ekamanganese (Em). In 1937, technetium (specifically the technetium-97 isotope) became the first predominantly artificial element to be produced, hence its name (from the Greek τεχνητός, meaning "craft", "art", or "artificial", + -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 particles. Long-lived technetium isotopes produced commercially are byproducts of the fission of uranium-235 in nuclear reactors and are extracted from nuclear fuel rods. Because even the longest-lived isotope of technetium has a relatively short half-life (4.21 million years), the 1952 detection of technetium in red giants helped to prove that stars can produce heavier elements.
Cornish[kw]
Elven gymyk yw teknetiom, niver 43 y'n Vosen Beriodek. Y furvell gymyk yw Tc. An hanow a dheu dhyworth an ger Greka tekhnetos, ow styrya kreftus. Yn 1952 gwelys veu linyow teknetiom yn spektrum an golow hag a wrug splanna dhyworth kowr-steren rudh. Drefen bos hanter-bewnans teknetiom 4 milvil bledhen dhe'n moyha, res o dhe'n golow ma furvya y'n steren hy honan. Prov veu hemma bos ster an tyller le mayth yw gwrys elvennow kymyk a bub sort. Usys yw teknetiom yn dyghtyans medhegel, gans gweres diskudha kellow kanker. Diskudhys veu teknetiom yn 1937 gans Emilio Segre ha Carlo Perrier yn Pennsol Palermo yn Itali. Ny gevys yw yn-mes arbrovjiow hwithrans nuklerek. Askorrys yw lies tonnas dhyworth pibellow keunys nuklerek usys, mes nyns eus devnydh anodho vytholl marnas yn mynsow munys yn unnik. Poos atomek teknetiom yw 98. Y boynt teudhi yw 2172°C ha'y boynt bryjyon yw 4877°C. Y dhosedh yw 11.5kg an liter. Radyoweythresek yw pub isotop. Alkan arghansek yw, mes kevys yw avel polter loos ynwedh.