Introduction
Group: None
Atomic Weight: 247
Period: 7
CAS Number: 7440-40-6
Classification
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)
Description • Uses/Function
Berkelium, the eighth member of the actinide transition series, was discovered in December 1949 by Thompson, Ghiorso, and Seaborg, and was the fifth transuranium element synthesized. It was produced by cyclotron bombardment of milligram amounts of 241Am with helium ions at Berkeley, California. The first isotope produced had a mass number of 243 and decayed with a half-life of 4.5 hours. Eleven isotopes are now known and have been synthesized. The existence of 249Bk, with a half-life of 320 days, makes it feasible to isolate berkelium in weighable amounts so that its properties can be investigated with macroscopic quantities. One of the first visible amounts of a pure berkelium compound, berkelium chloride, was produced in 1962. It weighed 3 billionth of a gram. Berkelium probably has not yet been prepared in elemental form, but it is expected to be a silvery metal, easily soluble in dilute mineral acids, and readily oxidized by air or oxygen at elevated temperatures to form the oxide. X-ray diffraction methods have been used to identify the following compounds: BkO2, BkO3, Bkf3, BkCl, and BkOCl. As with other actinide elements, berkelium tends to accumulate in the skeletal system. The maximum permissible body burden of 249Bk in the human skeleton is about 0.0004 micrograms. Because of its rarity, berkelium presently has no commercial or technological use. Berkelium-249 is available from O.R.N.L. at a cost of $160/microgram plus packing charges. 1
Physical Properties
Form:2 alpha
Electron Configuration: *[Rn] 7s2 5f9
n = 5
Melting Point:2* 1050 °C = 1323.15 K = 1922 °F
Boiling Point:2*
Sublimation Point:2
Triple Point:2
Critical Point:2
Form:2 beta
Melting Point:2* 986 °C = 1259.15 K = 1806.8 °F
Boiling Point:2*
Sublimation Point:2
Triple Point:2
Critical Point:2
Density:3 14.78 (alpha)/13.25 (beta) g/cm3
* - at 1 atm
Electron Configuration
Block: f
Highest Occupied Energy Level: 7
Valence Electrons: 2
Quantum Numbers:
ℓ = 3
mℓ = -2
ms = -½
Bonding
Ionization Potential
eV 4
kJ/mol
Ionization Potential
eV 4
kJ/mol
Ionization Potential
eV 4
kJ/mol
1
6.1979
598.0
Isotopes
Nuclide
Mass 5
Half-Life 5
Nuclear Spin 5
Binding Energy
235Bk
235.05658(43)#
20# s
1,774.29 MeV
236Bk
236.05733(43)#
1# min
1,782.37 MeV
237Bk
237.05700(24)#
1# min
7/2+#
1,790.44 MeV
238Bk
238.05828(31)#
2.40(8) min
1,798.51 MeV
239Bk
239.05828(25)#
3# min
7/2+#
1,806.58 MeV
240Bk
240.05976(16)#
4.8(8) min
1,814.65 MeV
241Bk
241.06023(22)#
4.6(4) min
(7/2+)
1,813.41 MeV
242Bk
242.06198(22)#
7.0(13) min
2-#
1,821.48 MeV
243Bk
243.063008(5)
4.5(2) h
(3/2-)
1,829.55 MeV
244Bk
244.065181(16)
4.35(15) h
(4-)#
1,837.62 MeV
245Bk
245.0663616(25)
4.94(3) d
3/2-
1,845.69 MeV
246Bk
246.06867(6)
1.80(2) d
2(-)
1,853.76 MeV
247Bk
247.070307(6)
1.38(25)E+3 a
(3/2-)
1,852.52 MeV
248Bk
248.07309(8)#
>9 a
6+#
1,860.59 MeV
249Bk
249.0749867(28)
330(4) d
7/2+
1,868.66 MeV
250Bk
250.078317(4)
3.212(5) h
2-
1,876.73 MeV
251Bk
251.080760(12)
55.6(11) min
(3/2-)#
1,875.49 MeV
252Bk
252.08431(22)#
1.8(5) min
1,883.56 MeV
253Bk
253.08688(39)#
10# min
1,891.63 MeV
254Bk
254.09060(32)#
1# min
1,890.39 MeV
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 5
Abundance
Compounds
Safety Information
Material Safety Data Sheet - ACI Alloys, Inc.
For More Information
External Links:
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
Sources
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:5.
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(8) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).