Skip to Main Content

About Berkelium

Berkelium Bohr

Berkelium is a transuranic member of the actinide series, with a silvery-white appearance. It does not occur naturally, and therefore was synthesized rather than being discovered. This synthesis was first accomplished by the team of Seaborg, Ghiorso, and Thompson at the University of California, Berkeley. This same team had been the first to produce americium and curium in 1944, and produced both berkelium and californium in 1949 and 1950. Americium had been given its name as a nod to its lanthanide analog that sits directly above it on the periodic table, europium. Likewise, berkelium was named after the city of its discovery just as its lanthanide analog, terbium, had been given a name derived from the town of Ytterby, Sweden, where the rare earth minerals were first found.

Berkelium is produced by bombarding uranium or plutonium with neutrons in a nuclear reactor, and can be separated from other products of these reactions with relative ease, compared to some of the other transuranic elements. Berkelium is a poor candidate for use as nuclear fuel due to an extremely low fission cross section for thermal neutrons. It is primarily used in the production of other transuranic elements, and all of its other uses are in basic research contexts.

Berkelium is extremely dangerous, as it is both highly radioactive and prone to accumulating in skeletal tissue. It is only used for scientific research and to produce some of the heavier actinides.

Berkelium Properties

Berkelium Bohr ModelBerkelium is a Block F, Group 3, Period 7 element. The number of electrons in each of berkelium's shells is 2, 8, 18, 32, 27, 8, 2 and its electron configuration is [Rn] 5f9 7s2. The berkelium atom has a radius of In its elemental form, berkelium's CAS number is 7440-40-6. Berkelium is a radioactive element produced in nature by beta decay and neutron capture in highly concentrated uranium-bearing deposits. It is the rarest naturally occurring element. Berkelium was discovered by Stanley G. Thompson, Albert Ghiorso and Glenn T. Seaborg at the Lawrence Berkeley Natinal Laboratory in 1949. It was the fifth synthetic transuranium element of the actinide series to be discovered.

Berkelium information, including properties, research, applications and other useful facts are discussed below. Scientific facts such as the atomic structure, ionization energy, abundance on Earth, conductivity and thermal properties are included.

Symbol: Bk
Atomic Number: 97
Atomic Weight: 247
Element Category: Actinide
Group, Period, Block: n/a, 7, f
Color: silvery-white/ unknown
Other Names: Berkelio, Berquélio
Melting Point: 986 °C, 1806.8 °F, 1259.15 K
Boiling Point: N/A
Density: 14790 kg·m3
Liquid Density @ Melting Point: N/A
Density @ 20°C: 14.79 g/cm3
Density of Solid: 14780 kg·m3
Specific Heat: N/A
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): N/A
Heat of Vaporization (kJ·mol-1): N/A
Heat of Atomization (kJ·mol-1): 291
Thermal Conductivity: 10 W·m-1·K-1
Thermal Expansion: N/A
Electrical Resistivity: N/A
Tensile Strength: N/A
Molar Heat Capacity: N/A
Young's Modulus: N/A
Shear Modulus: N/A
Bulk Modulus: N/A
Poisson Ratio: N/A
Mohs Hardness: N/A
Vickers Hardness: N/A
Brinell Hardness: N/A
Speed of Sound: N/A
Pauling Electronegativity: 1.3
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.2
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 2.7
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 97
Protons: 97
Neutrons: 150
Electron Configuration: [Rn] 5f9 7s2
Atomic Radius: 170 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: N/A
Covalent Radius (Å): 1.68
Van der Waals Radius: N/A
Oxidation States: 3, 4
Phase: Solid
Crystal Structure: hexagonal close-packed
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) Unknown
1st Ionization Energy: 601 kJ·mol-1 (estimated)
2nd Ionization Energy: N/A
3rd Ionization Energy: N/A
CAS Number: 7440-40-6
EC Number: N/A
MDL Number: N/A
Beilstein Number: N/A
SMILES Identifier: [Bk]
InChI Identifier: InChI=1S/Bk
PubChem CID: 23971
ChemSpider ID: 22409
Earth - Total: N/A
Mercury - Total: N/A
Venus - Total: N/A
Earth - Seawater (Oceans), ppb by weight: N/A
Earth - Seawater (Oceans), ppb by atoms: N/A
Earth -  Crust (Crustal Rocks), ppb by weight: N/A
Earth -  Crust (Crustal Rocks), ppb by atoms: N/A
Sun - Total, ppb by weight: N/A
Sun - Total, ppb by atoms: N/A
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: N/A
Meterorite (Carbonaceous), ppb by atoms: N/A
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: N/A
Universe, ppb by atom: N/A
Discovered By: Lawrence Berkeley Nat'l Laboratory
Discovery Date: 1949
First Isolation: N/A

Berkelium Isotopes

Berkelium is an artificial element. It has no stable isotopes.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
235Bk 235.05658(43)# 20# s α to 231Am; β+ to 235Cm N/A N/A 1768.168945 -
236Bk 236.05733(43)# 1# min α to 232Am; β+ to 236Cm N/A N/A 1775.541016 -
237Bk 237.05700(24)# 1# min α to 233Am; β+ to 237Cm 7/2+# N/A 1783.802002 -
238Bk 238.05828(31)# 2.40(8) min α to 234Am; SF; β+ to 238Cm N/A N/A 1790.812012 -
239Bk 239.05828(25)# 3# min α to 235Am; β+ to 239Cm 7/2+# N/A 1798.793945 -
240Bk 240.05976(16)# 4.8(8) min β+ to 240Cm; α to 246Am; SF N/A N/A 1805.573975 -
241Bk 241.06023(22)# 4.6(4) min α to 237Am; β+ to 241Cm (7/2+) N/A 1813.203003 -
242Bk 242.06198(22)# 7.0(13) min β+ to 242Cm; SF 2-# N/A 1819.572998 -
243Bk 243.063008(5) 4.5(2) h β+ to 243Cm; α to 239Am (3/2-) N/A 1826.757568 -
244Bk 244.065181(16) 4.35(15) h β+ to 244Cm; α to 240Am (4-)# N/A 1832.811035 -
245Bk 245.0663616(25) 4.94(3) d EC to 245Cm; α to 241Am 3/2- N/A 1839.776123 -
246Bk 246.06867(6) 1.80(2) d EC to 246Cm; α to 242Am 2(-) N/A 1845.694336 -
247Bk 247.070307(6) 1.38(25)×103y α to 243Am (3/2-) N/A 1852.24585 -
248Bk 248.07309(8)# 23.7 h EC to 248Cm; α to 244Am; β- to 248Cf 6+# N/A 1857.725952 -
249Bk 249.0749867(28) 330(4) d α to 245Am; β- to 249Cf; SF 7/2+ 2 1864.02771 -
250Bk 250.078317(4) 3.212(5) h β- to 250Cf 2- N/A 1868.996704 -
251Bk 251.080760(12) 55.6(11) min β- to 251Cf; α to 247Am (3/2-)# N/A 1874.792358 -
252Bk 252.08431(22)# 1.8(5) min β- to 252Cf; α to 248Am N/A N/A 1879.557007 -
253Bk 253.08688(39)# 10# min β- to 253Cf N/A N/A 1885.228027 -
254Bk 254.09060(32)# 1# min β- to 254Cf N/A N/A 1889.833984 -
Berkelium Elemental Symbol

Recent Research & Development for Berkelium

  • Gerard F. Payne, Joseph R. Peterson, Possible stabilization of the tetravalent oxidation state of berkelium and californium in acetonitrile with triphenylarsine oxide, Inorganica Chimica Acta, Volume 139, Issues 1–2, 1 December 1987
  • J.K Gibson, R.G Haire, Preparation and X-ray diffraction studies of hydrides of curium, berkelium and californium, Journal of the Less Common Metals, Volume 127, January 1987
  • D.E. Hobart, J.R. Peterson, The chemistry of berkelium: A review, Journal of the Less Common Metals, Volume 121, July 1986
  • J.K. Gibson, R.G. Haire, Preparation and X-ray diffraction studies of berkelium hydrides, Journal of the Less Common Metals, Volume 109, Issue 2, 15 July 1985
  • R.G Haire, J.R Peterson, U Benedict, C Dufour, X-ray diffraction of berkelium metal under pressure to 57 GPa, Journal of the Less Common Metals, Volume 102, Issue 1, September 1984
  • Yuan-fang Liu, Cheng Luo, Hans R. von Gunten, Glenn T. Seaborg, A procedure for a fast separation of berkelium and cerium, Inorganic and Nuclear Chemistry Letters, Volume 17, Issues 7–8, 1981
  • J. Fuger, R.G. Haire, J.R. Peterson, A new determination of the enthalpy of solution of berkelium metal and the standard enthalpy of formation of Bk3+ (aq), Journal of Inorganic and Nuclear Chemistry, Volume 43, Issue 12, 1981
  • D.D. Ensor, J.R. Peterson, R.G. Haire, J.P. Young, Absorption spectrophotometric study of berkelium(III) and (IV) fluorides in the solid state, Journal of Inorganic and Nuclear Chemistry, Volume 43, Issue 5, 1981
  • R.P. Turcotte, T.D. Chikalla, R.G. Haire, J.A. Fahey, Phase behaviour in the berkelium-oxygen system, Journal of Inorganic and Nuclear Chemistry, Volume 42, Issue 12, 1980
  • J.N Stevenson, J.R Peterson, Preparation and structural studies of elemental curium-248 and the nitrides of curium-248 and berkelium-249, Journal of the Less Common Metals, Volume 66, Issue 2, August 1979
  • C.B. Finch, R.L. Fellows, J.P. Young, Self-luminescence of several fluorite-structure halides doped with curium or berkelium, Journal of Luminescence, Volume 16, Issue 1, January 1978
  • R.G. Haire, J.A. Fahey, The oxysulfates and oxysulfides of americium, curium and berkelium, Journal of Inorganic and Nuclear Chemistry, Volume 39, Issue 5, 1977
  • J. Fuger, J.R. Peterson, J.N. Stevenson, M. Noé, R.G. Haire, Determination of the heat of solution of berkelium metal, Journal of Inorganic and Nuclear Chemistry, Volume 37, Issues 7–8, July–August 1975
  • R.G. Gutmacher, D.D. Bodé Jr., R.W. Lougheed, E.K. Hulet, The stability of tetravalent berkelium in acid solution and the absorption spectra of Bk(IV) and Bk(III), Journal of Inorganic and Nuclear Chemistry, Volume 35, Issue 3, March 1973
  • R.M. Harbour, Elution positions of europium, berkelium, terbium and einsteinium from a cation exchange resin column with a-hydroxyisobutyric acid, Journal of Inorganic and Nuclear Chemistry, Volume 34, Issue 8, August 1972
  • J.A. Fahey, J.R. Peterson, R.D. Baybarz, Some properties of berkelium metal and the apparent trend toward divalent character in the transcurium actinide metals, Inorganic and Nuclear Chemistry Letters, Volume 8, Issue 1, January 1972
  • R.P. Turcotte, T.D. Chikalla, L. Eyring, Oxygen decomposition pressures and thermodynamic data for nonstoichiometric berkelium berkelium oxide, Journal of Inorganic and Nuclear Chemistry, Volume 33, Issue 11, November 1971
  • J.R. Peterson, J.A. Fahey, R.D. Baybarz, The crystal structures and lattice parameters of berkelium metal, Journal of Inorganic and Nuclear Chemistry, Volume 33, Issue 10, October 1971
  • R.C. Propst, M.L. Hyder, Electrochemistry of berkelium in acidic aqueous solution, Journal of Inorganic and Nuclear Chemistry, Volume 32, Issue 7, July 1970
  • E.P. Horwitz, C.A.A. Bloomquist, D.J. Henderson, D.E. Nelson, The extraction chromatography of americium, curium, berkelium and californium with di(2-ethylhexyl)orthophosphoric acid, Journal of Inorganic and Nuclear Chemistry, Volume 31, Issue 10, October 1969