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Berkelium

From Academic Kids

curiumberkeliumcalifornium
Tb
Bk
   
 
 
Image:-TableImage.png
Known properties
Name, Symbol, Number Berkelium, Bk, 97
Chemical series Actinides
Period, Block 7, f
Appearance unknown; probably metallic,
silvery white or gray
Atomic weight [247] amu
Electron configuration [Rn] 5f9 7s2
e- 's per energy level 2,8,18,32,27,8,2
State of matter solid
Density 14780 kg/m3
Most stable isotopes
iso NA half-life DM DE MeV DP
245Bk {syn.} 4.94 d ε
α
0.810
6.455
245Cm
241Am
246Bk {syn.} 1.8 d α
ε
6.070
1.350
242Am
246Cm
247Bk {syn.} 1380 y α 5.889 243Am
248Bk {syn.} >9 y α 5.803 244Am
249Bk {syn.} 320 d α
SF
β-
5.526
 
0.125
245Am


 
249Cf

Berkelium is a synthetic element in the periodic table that has 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. Berkelium was the fifth transuranic element to be synthesized.

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Contents

Notable characteristics

Weighable amounts of berkelium-249 (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 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 americium-241 with alpha particles to produce berkelium-243 (half-life 4.5 hours) and two free neutrons. One of the longest lived isotopes of the element, berkelium-249 (half-life 320 days), was later synthesized by subjecting a curium-244 target with an intense beam of neutrons.

Isotopes

19 radioisotopes of berkelium have been characterized, with the most stable being Bk-247 with a half-life of 1380 years, Bk-248 with a half-life of >9 years, and Bk-249 with a half-life of 320 days. All of the remaining radioactive isotopes have half-lifes that are less than 5 days, and the majority of these have half lifes that are less than 5 hours. This element also has 2 meta states, with the most stable being Bk-248m (t? 23.7 hours). The isotopes of berkelium range in atomic weight from 235.057 amu (Bk-235) to 254.091 amu (Bk-254).

References

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