Berkelium (Bk)

Isotopes of Berkelium

Isotope Atomic Mass Half-life Mode of Decay Nuclear Spin Nuclear Magnetic Moment
Bk-245 245.06636 4.94 days EC to Cm-245;
α to Am-241
3/2 No data available 
Bk-246 246.0687 1.80 days EC to Cm-246;
α to Am-242
2 No data available 
Bk-247 247.070300 1400 years α to Am-243 3/2 No data available 
Bk-248 248.07310 23.70 hours EC to Cm-248;
α to Am-244;
ß- to Cf-248
1 No data available 
Bk-249 249.07498 320 days α to Am-245;
ß- to Cf-249; SF
7/2 2.0
Bk-250  250.07831 3.217 hours ß- to Cf-250 2 No data available 



Berkelium is a radioactive rare earth metal, discovered in 1949 by Glenn T. Seaborg, Stanley G. Thompson and Albert Ghiorso, and named after the University of California at Berkeley, USA. Perhaps the first visible sample of a pure berkelium compound, berkelium chloride, was produced in 1962. It weighed just 3 billionths of a gram.

Berkelium is a soft, silvery-white metal that emits low-energy electrons and is therefore relatively safe to handle. Its most stable α form has a hexagonal symmetry. The crystal has a double-hexagonal close-packing structure, which changes with pressure and temperature. It transforms to the beta modification, which has a face-centered symmetry. Berkelium dissolves in various aqueous inorganic acids. It does not react rapidly with oxygen at room temperature; however, it reacts with molten metals, hydrogen, halogens, chalcogens and pnictogens to form various binary compounds.

There are no known commercial applications of berkelium outside of scientific research. Berkelium-249 is a common target nuclide to prepare still heavier transuranic elements and transactinides, such as lawrencium, rutherfordium and bohrium.

Properties of Berkelium

Name Berkelium
Symbol Bk
Atomic number 97
Atomic weight [247]
Standard state Solid at 298 °K
CAS Registry ID 7440-40-6
Group in periodic table N/A
Group name Actinoid
Period in periodic table 7 (Actinoid)
Block in periodic table f-block
Color Unknown, but probably metallic and silvery white or grey in appearance
Classification Metallic
Melting point 1259 °K [or 986 °C or 1807 °F]
Boiling point No data available
Density of solid 14.78 g/cm3
Electron configuration [Rn]5f97s2