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Author: langbot
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English[en]
Berkelium is a transuranic radioactive chemical element with the symbol Bk and atomic number 97. It is a member of the actinide and transuranium element series. It is named after the city of Berkeley, California, the location of the Lawrence Berkeley National Laboratory (then the University of California Radiation Laboratory) where it was discovered in December 1949. Berkelium was the fifth transuranium element discovered after neptunium, plutonium, curium and americium. The major isotope of berkelium, 249Bk, is synthesized in minute quantities in dedicated high-flux nuclear reactors, mainly at the Oak Ridge National Laboratory in Tennessee, United States, and at the Research Institute of Atomic Reactors in Dimitrovgrad, Russia. The production of the second-most important isotope, 247Bk, involves the irradiation of the rare isotope 244Cm with high-energy alpha particles. Just over one gram of berkelium has been produced in the United States since 1967. There is no practical application of berkelium outside scientific research which is mostly directed at the synthesis of heavier transuranium elements and superheavy elements. A 22-milligram batch of berkelium-249 was prepared during a 250-day irradiation period and then purified for a further 90 days at Oak Ridge in 2009. This sample was used to synthesize the new element tennessine for the first time in 2009 at the Joint Institute for Nuclear Research, Russia, after it was bombarded with calcium-48 ions for 150 days. This was the culmination of the Russia–US collaboration on the synthesis of the heaviest elements on the periodic table. Berkelium is a soft, silvery-white, radioactive metal. The berkelium-249 isotope emits low-energy electrons and thus is relatively safe to handle. It decays with a half-life of 330 days to californium-249, which is a strong emitter of ionizing alpha particles. This gradual transformation is an important consideration when studying the properties of elemental berkelium and its chemical compounds, since the formation of californium brings not only chemical contamination, but also free-radical effects and self-heating from the emitted alpha particles.
Cornish[kw]
Elven gymyk yw berkeliom, niver 97 y'n Vosen Beriodek. An hanow a dheu dhyworth tre Berkeley yn Kaliforni, an Statys Unys, le may feu gwrys rag an kynsa prys. Y furvell gymyk yw Bk. Ny gevys yw berkeliom war an Norvys marnas yn arbrovjiow hwithrans nuklerek. Pur beryllus yw drefen y radyoweythresek glew. Askorrys veu rag an kynsa tro war an 19ves mis Kevardhu, 1949, yn Pennskol Kaliforni yn Berkeley gans Stanley Thompson, Albert Ghiorso ha Glenn Seaborg. Nyns eus devnydh vyth oll dhodho. Hanter bewnans an isotop moyha kemmyn yw 320 dydh. Y boos atomek yw 247.1 ha'y boynt teudhi yw 1047°C. Ny wodhvedhys pana yw y boynt bryjyon. Alkan arghansek radyoweythresek yw. Wosa y dhiskudhyans (hag elvennow erel y'n unn bagas), an lyver termyn The New Yorker a brofyas y talvia dhe Bennskol Kaliforni henwel an elvennow nowydh 'universitium', 'ofium', 'californium' ha 'berkelium'. An gorthyp gans Seaborg o aga bos prederi a-dro dhe hemma, mes ny vynsons ri an chons dhe Evrok Nowydh henwel an dhew elven nessa 'newium' ha 'yorkium'. The New Yorker a worthyp bos an henwyn dhedha, ha aga bos owth oberi war an elvennow nowydh.