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Definition: californium from The Penguin English Dictionary

a radioactive metallic chemical element that is artificially produced by bombarding curium 244 and americium 243 with neutrons: symbol Cf, atomic number 98 [scientific Latin californium, named after California, state of USA, where it was first made].

Summary Article: californium from The Columbia Encyclopedia

(kăl'ĭfôr´´nēӘm) [from California], artificially produced, radioactive metallic chemical element; symbol Cf; at. no. 98; mass no. of most stable isotope 251; m.p. about 900degrees Celsius; b.p. about 1,470degrees Celsius; density unknown; valence +3. Californium is a member of the actinide series of chemical elements, found in Group 3 of the periodic table. Its chemical properties are similar to those of lanthanum. Eighteen isotopes of californium are known, with half-lives ranging from about 40 sec for californium-239 to about 900 years for californium-251, the most stable isotope. Californium-249 (half-life 351 years) is most useful for chemical investigations; it is obtained by the decay of berkelium-249. Four solid compounds of californium have been prepared; they are the trichloride, oxychloride, oxyfluoride, and oxide. Californium-252 (half-life 2.6 years) is produced in nuclear reactors for use as a source of neutrons for counters and electronic systems in industrial and medical applications. The sixth transuranium element to be synthesized, californium has yet to be found in the earth's crust. Californium was first produced in 1950 by Glenn T. Seaborg, Stanley G. Thompson, Albert Ghiorso, and Kenneth Street, Jr., in a cyclotron at the Univ. of California at Berkeley by bombarding curium-242 with alpha particles, resulting in californium-245 (half-life 45 min).

The Columbia Encyclopedia, © Columbia University Press 2017

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