curium – berkelium – californium Tb Bk         Full table
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.

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 billionth 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_½ 23.7 hours). The isotopes of berkelium range in atomic weight from 235.057 amu (Bk-235) to 254.091 amu (Bk-254).

References

• Los Alamos National Laboratory - Berkelium
• It's Elemental - Berkelium

External links

• WebElements.com - Berkelium
• EnvironmentalChemistry.com - Berkelium