Isotopes of berkelium

Berkelium (Bk) has no stable isotopes. There are 20 known radioisotopes, from ²³⁵Bk to ²⁵⁴Bk, and 6 nuclear isomers. A standard atomic mass cannot be given. The isotope with the longest half-life is ²⁴⁷Bk with a half-life of 1,380 years.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin
	excitation energy
235Bk	97	138	235.05658(43)#	20# s	α	231Am
					β+	235Cm
236Bk	97	139	236.05733(43)#	1# min	α	232Am
					β+	236Cm
237Bk	97	140	237.05700(24)#	1# min	α	233Am	7/2+#
					β+ (rare)	237Cm
238Bk	97	141	238.05828(31)#	2.40(8) min	α	234Am
					β+, SF (.048%)	(various)
					β+ (rare)	238Cm
239Bk	97	142	239.05828(25)#	3# min	α	235Am	7/2+#
					β+	239Cm
240Bk	97	143	240.05976(16)#	4.8(8) min	β+ (90%)	240Cm
					α (10%)	236Am
					β+, SF (.002%)	(various)
241Bk	97	144	241.06023(22)#	4.6(4) min	α	237Am	(7/2+)
					β+ (rare)	241Cf
242Bk	97	145	242.06198(22)#	7.0(13) min	β+ (99.99%)	242Cm	2-#
					β+, SF (3E-4%)	(various)
242mBk	200(200)# keV			600(100) ns
243Bk	97	146	243.063008(5)	4.5(2) h	β+ (99.85%)	243Cm	(3/2-)
					α (.15%)	239Am
244Bk	97	147	244.065181(16)	4.35(15) h	β+ (99.99%)	244Cm	(4-)#
					α (.006%)	240Am
245Bk	97	148	245.0663616(25)	4.94(3) d	EC (99.88%)	245Cm	3/2-
					α (.12%)	241Am
246Bk	97	149	246.06867(6)	1.80(2) d	β+ (99.8%)	246Cm	2(-)
					α (.2%)	242Am
247Bk	97	150	247.070307(6)	1.38(25)E+3 a	α	243Am	(3/2-)
					SF (rare)	(various)
248Bk	97	151	248.07309(8)#	>9 a	α	244Am	6+#
248mBk	30(70)# keV			23.7(2) h			1(-)
249Bk	97	152	249.0749867(28)	330(4) d	β-	249Cm	7/2+
					α (.00145%)	245Am
					SF (4.7E-8%)	(various)
249mBk	8.80(10) keV			300 µs			(3/2-)
250Bk	97	153	250.078317(4)	3.212(5) h	β-	250Cf	2-
250m1Bk	35.59(5) keV			29(1) µs			(4+)
250m2Bk	84.1(21) keV			213(8) µs			(7+)
251Bk	97	154	251.080760(12)	55.6(11) min	β-	251Cf	(3/2-)#
					α (1E-5%)	247Am
251mBk	35.5(13) keV			58(4) µs			(7/2+)#
252Bk	97	155	252.08431(22)#	1.8(5) min	β-	252Cf
					α	248Am
253Bk	97	156	253.08688(39)#	10# min	β-	253Cf
254Bk	97	157	254.09060(32)#	1# min	β-	254Cf

Notes

• 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.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

• Isotope masses from:
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. doi:10.1016/j.nuclphysa.2003.11.001.{{cite journal}}: CS1 maint: multiple names: authors list (link)
• Isotopic compositions and standard atomic masses from:
  • J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. {{cite journal}}: Unknown parameter |laysummary= ignored (help)
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. doi:10.1016/j.nuclphysa.2003.11.001.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. {{cite web}}: Check date values in: |accessdate= (help)
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide (ed.). CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859. {{cite book}}: Unknown parameter |nopp= ignored (|no-pp= suggested) (help)