AskDefine | Define berkelium

Dictionary Definition

berkelium n : a radioactive transuranic element; discovered by bombarding americium with helium [syn: Bk, atomic number 97]

User Contributed Dictionary

see Berkelium

English

Noun

  1. A transuranic chemical element (symbol Bk) with an atomic number of 97.

Related terms

Translations

External links

For etymology and more information refer to: http://elements.vanderkrogt.net/elem/bk.html (A lot of the translations were taken from that site with permission from the author)

Finnish

Noun

  1. berkelium

Extensive Definition

Bk redirects here. For other uses of the abbreviation, see BK (disambiguation). Berkelium ( or /ˈbɝkliəm/ ) is a synthetic element with the symbol Bk and atomic number 97. A radioactive metallic element in the actinide series, berkelium was first synthesized by bombarding americium with alpha particles (helium ions) and was named after Berkeley, California and the University of California, Berkeley. Berkelium was the fifth transuranic element to be synthesized.

Notable characteristics

Weighable amounts of 249Bk (half-life 314 days) make it possible to determine some of its properties using macroscopic quantities. As of 2004 it had not been isolated in its elemental form, but it is predicted to be a silvery metal that would easily oxidize in air at elevated temperatures and would be soluble in dilute mineral acids.
X-ray diffraction techniques have been used to identify various berkelium compounds such as berkelium dioxide (BkO2), berkelium fluoride (BkF3), berkelium oxychloride (BkOCl), and berkelium trioxide (BkO3). In 1962 visible amounts of berkelium chloride (BkCl3) were isolated that weighed 3 billionths of a gram. This was the first time visible amounts of a pure berkelium compound were produced.
Like other actinides, berkelium bio-accumulates in skeletal tissue. This element has no known uses outside of basic research and plays no biological role.

History

Berkelium was first synthesized by Glenn T. Seaborg, Albert Ghiorso, Stanley G. Thompson, and Kenneth Street, Jr at the University of California, Berkeley in December 1949. The team used a cyclotron to bombard a milligram-sized target of 241Am with alpha particles to produce 243Bk (half-life 4.5 hours) and two free neutrons. One of the longest lived isotopes of the element, 249Bk (half-life 330 days), was later synthesized by subjecting a 244Cm target with an intense beam of neutrons.

Isotopes

19 radioisotopes of berkelium have been characterized, with the most stable being 247Bk with a half-life of 1380 years, 248Bk with a half-life of >9 years, and 249Bk with a half-life of 330 days. All of the remaining radioactive isotopes have half-lives that are less than 5 days, and the majority of these have half-lives that are less than 5 hours. This element also has 2 meta states, with the most stable being 248mBk (t½ 23.7 hours). The isotopes of berkelium range in atomic weight from 235.057 u (235Bk) to 254.091 u (254Bk).

Nuclear fuel cycle

In the nuclear fuel cycle, berkelium is produced by beta decay of curium. The first curium isotope to undergo beta decay is Cm-249 with a halflife of just over an hour, so Bk-249 is the only isotope of berkelium produced in significant quantities in nuclear reactors. Production of Bk-249 requires 11 successive neutron captures on uranium-238 without nuclear fission or alpha decay, so it is only produced in small amounts.
249Bk has a moderately large neutron capture cross section of 710 barns for thermal neutrons, 1200 barns resonance integral, but very low fission cross section for thermal neutrons. If still in a thermal reactor, much of it will therefore be converted to 250Bk which quickly decays to californium-250, but some alpha decays to curium-245.
berkelium in Arabic: بركليوم
berkelium in Belarusian: Берклій
berkelium in Bosnian: Berkelijum
berkelium in Catalan: Berkeli
berkelium in Czech: Berkelium
berkelium in Corsican: Berkeliu
berkelium in Danish: Berkelium
berkelium in German: Berkelium
berkelium in Estonian: Berkeelium
berkelium in Modern Greek (1453-): Μπερκέλιο
berkelium in Spanish: Berkelio
berkelium in Esperanto: Berkelio
berkelium in Basque: Berkelio
berkelium in Persian: برکلیوم
berkelium in French: Berkélium
berkelium in Friulian: Berkeli
berkelium in Manx: Berkelium
berkelium in Galician: Berquelio
berkelium in Korean: 버클륨
berkelium in Armenian: Բերկլիում
berkelium in Croatian: Berkelij
berkelium in Ido: Berkelio
berkelium in Indonesian: Berkelium
berkelium in Italian: Berkelio
berkelium in Hebrew: ברקליום
berkelium in Javanese: Berkelium
berkelium in Haitian: Bèkelyòm
berkelium in Latin: Berkelium
berkelium in Latvian: Berklijs
berkelium in Luxembourgish: Berkelium
berkelium in Lithuanian: Berklis
berkelium in Lojban: jinmrberkeli
berkelium in Hungarian: Berkélium
berkelium in Malayalam: ബെര്‍കിലിയം
berkelium in Dutch: Berkelium
berkelium in Japanese: バークリウム
berkelium in Norwegian: Berkelium
berkelium in Norwegian Nynorsk: Berkelium
berkelium in Polish: Berkel
berkelium in Portuguese: Berquélio
berkelium in Romanian: Berkeliu
berkelium in Russian: Берклий
berkelium in Sicilian: Berkeliu
berkelium in Simple English: Berkelium
berkelium in Slovak: Berkélium
berkelium in Slovenian: Berkelij
berkelium in Serbian: Берклијум
berkelium in Serbo-Croatian: Berklijum
berkelium in Saterfriesisch: Berkelium
berkelium in Finnish: Berkelium
berkelium in Swedish: Berkelium
berkelium in Thai: เบอร์คีเลียม
berkelium in Turkish: Berkelyum
berkelium in Ukrainian: Берклій
berkelium in Chinese: 锫
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