berkelium

[ber-kee-lee-uhm]
noun Chemistry.
a transuranic element. Symbol: Bk; atomic number: 97; atomic weight: 249 (?).

Origin:
1945–50; named after Berkeley, California, where it was discovered; see -ium

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World English Dictionary
berkelium (bɜːˈkiːlɪəm, ˈbɜːklɪəm)
 
n
a metallic transuranic element produced by bombardment of americium. Symbol: Bk; atomic no: 97; half-life of most stable isotope, 247Bk: 1400 years; valency: 3 or 4; relative density: 14 (est)
 
[C20: named after Berkeley1, where it was discovered]

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Medical Dictionary

berkelium ber·ke·li·um (bər-kē'lē-əm, bûrk'lē-əm)
n.
Symbol Bk
A synthetic radioactive element. Its most stable isotope, Bk 247, has a half-life of 1,380 years. Atomic number 97; melting point 1,050°C; valence 3, 4.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Science Dictionary
berkelium   (bər-kē'lē-əm, bûrk'lē-əm)  Pronunciation Key 
Symbol Bk
A synthetic, radioactive metallic element of the actinide series that is produced from americium, curium, or plutonium. Its most stable isotope has a half-life of about 1,400 years. Atomic number 97; melting point 986°C; valence 3, 4. See Periodic Table.
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Encyclopedia Britannica
Encyclopedia

berkelium

synthetic chemical element of the actinoid series of the periodic table, atomic number 97. Not occurring in nature, berkelium (as the isotope berkelium-243) was discovered in December 1949 by Stanley G. Thompson, Albert Ghiorso, and Glenn T. Seaborg at the University of California at Berkeley as a product resulting from the helium-ion bombardment of americium-241 (atomic number 95) in a 152-centimetre (60-inch) cyclotron. All berkelium isotopes are radioactive; berkelium-247 is the longest lived (1,400-year half-life). Berkelium-249 (314-day half-life) has been widely used in the chemical studies of the element because it can be produced in weighable amounts that are isotopically pure by nuclear reactions beginning with curium-244. Metallic berkelium has not yet been prepared, but it should be electropositive, reactive, and silver-coloured like the other actinide metals, with a specific gravity of about 14. Tracer chemical investigations have shown that berkelium exists in aqueous solutions in the +3 and +4 oxidation states, presumably as Bk3+ and Bk4+ ions. The solubility properties of berkelium in its two oxidation states are entirely analogous to those of the other actinoids and to the lanthanoid elements in the corresponding oxidation states. Solid compounds, including the oxides BkO2 and Bk2O3 and the chloride BkCl3, have been synthesized on the submicrogram scale

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Example sentences for berkelium
Berkelium was the fifth transuranic element to be synthesized.
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