Isotopes of berkelium (97Bk)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
245Bk synth 4.94 d ε 245Cm
α 241Am
246Bk synth 1.8 d α 242Am
ε 246Cm
247Bk synth 1380 y α 243Am
248Bk synth >300 y[2] α 244Am
249Bk synth 330 d β− 249Cf
α 245Am
SF –

Berkelium (97Bk) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 243Bk in 1949. There are 20 known radioisotopes, from 230Bk and 233Bk to 253Bk (with the exception of 235Bk and 237Bk), and 6 nuclear isomers. The longest-lived isotope is 247Bk with a half-life of 1,380 years.

List of isotopes

Nuclide
[n 1]		 Z N Isotopic mass (Da)
[n 2][n 3]		 Half-life
 Decay
mode
[n 4]		 Daughter
isotope
 Spin and
parity
[n 5][n 6]
Excitation energy[n 6]
230Bk[3] 97 133 ~0.46 s α 226Am
233Bk[4] 97 136 21+48
−17 s		 α 229Am 3/2-#
234Bk[5] 97 137 19+6
−4 s		 β+ 234Cm 3-#
β+, SF (various)
α 230Am
236Bk[6] 97 139 236.05733(43)# 22+13
−6 s		 β+ (96%) 236Cm 4+#
β+, SF (4%) (various)
238Bk 97 141 238.05828(31)# 2.40(8) min β+ 238Cm 1#
β+, SF (0.048%) (various)
α (rare) 234Am
239Bk[7] 97 142 239.05828(25)# 100# s β+ (>99%) 239Cm (7/2+)
α (<1%) 235Am
SF (<1%) (various)
240Bk 97 143 240.05976(16)# 4.8(8) min β+ 240Cm 7-#
β+, SF (0.002%) (various)
α (rare) 236Am
241Bk[8] 97 144 241.06023(22)# 4.6(4) min β+ 241Cm (7/2+)
α (rare) 237Am
242Bk 97 145 242.06198(22)# 7.0(13) min β+ 242Cm 2−#
β+, SF (<3×10−5%) (various)
242mBk 200(200)# keV 600(100) ns SF (various)
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 EC (99.8%) 246Cm 2(−)
α (.2%) 242Am
247Bk 97 150 247.070307(6) 1.38(25)×103 y α 243Am (3/2−)
SF (rare) (various)
248Bk 97 151 248.07309(8)# >300 y[9] α 244Am 6+#
248mBk 30(70)# keV 23.7(2) h β− 248Cf 1(−)
249Bk[n 7] 97 152 249.0749867(28) 330(4) d β− 249Cf 7/2+
α (.00145%) 245Am
SF (4.7×10−8%) (various)
249mBk 8.80(10) keV 300 μs IT 249Bk (3/2−)
250Bk 97 153 250.078317(4) 3.212(5) h β− 250Cf 2−
250m1Bk 35.59(5) keV 29(1) μs IT 250Bk (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 (10−5%) 247Am
251mBk 35.5(13) keV 58(4) μs IT 251Bk (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
This table header & footer:
  1. ↑ mBk – Excited nuclear isomer.
  2. ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ↑ Modes of decay:
    EC:Electron capture
    SF:Spontaneous fission
  5. ↑ ( ) spin value – Indicates spin with weak assignment arguments.
  6. 1 2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  7. ↑ Easiest isotope to synthesize

Actinides vs fission products

Actinides and fission products by half-life
Actinides[10] by decay chain Half-life
range (a)		 Fission products of 235U by yield[11]
4n 4n + 1 4n + 2 4n + 3 4.5–7% 0.04–1.25% <0.001%
228Ra№ 4–6 a 155Euþ
244Cmƒ 241Puƒ 250Cf 227Ac№ 10–29 a 90Sr 85Kr 113mCdþ
232Uƒ 238Puƒ 243Cmƒ 29–97 a 137Cs 151Smþ 121mSn
248Bk[12] 249Cfƒ 242mAmƒ 141–351 a

No fission products have a half-life in the range of 100 a–210 ka ...

241Amƒ 251Cfƒ[13] 430–900 a
226Ra№ 247Bk 1.3–1.6 ka
240Pu 229Th 246Cmƒ 243Amƒ 4.7–7.4 ka
245Cmƒ 250Cm 8.3–8.5 ka
239Puƒ 24.1 ka
230Th№ 231Pa№ 32–76 ka
236Npƒ 233Uƒ 234U№ 150–250 ka 99Tc₡ 126Sn
248Cm 242Pu 327–375 ka 79Se₡
1.53 Ma 93Zr
237Npƒ 2.1–6.5 Ma 135Cs₡ 107Pd
236U 247Cmƒ 15–24 Ma 129I₡
244Pu 80 Ma

... nor beyond 15.7 Ma[14]

232Th№ 238U№ 235Uƒ№ 0.7–14.1 Ga

See also

References

  1. ↑ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. ↑ Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. doi:10.1016/0029-5582(65)90719-4.
  3. ↑ Heinz, Sophie. "Observation of new neutron-deficient multinucleon transfer reactions isotopes with Z ≥ 92 in multinucleon transfer reactions". Slideplayer. GSI Helmholtzzentrum and Justus-Liebig-Universität Gießen. Retrieved 23 June 2023.
  4. ↑ Devaraja, H. M.; Heinz, S.; Beliuskina, O.; Comas, V.; Hofmann, S.; Hornung, C.; Münzenberg, G.; Nishio, K.; Ackermann, D.; Gambhir, Y. K.; Gupta, M.; Henderson, R. A.; Heßberger, F. P.; Khuyagbaatar, J.; Kindler, B.; Lommel, B.; Moody, K. J.; Maurer, J.; Mann, R.; Popeko, A. G.; Shaughnessy, D. A.; Stoyer, M. A.; Yeremin, A. V. (2 September 2015). "Observation of new neutron-deficient isotopes with Z≥92 in multinucleon transfer reactions" (PDF). Physics Letters B. 748: 199–203. Bibcode:2015PhLB..748..199D. doi:10.1016/j.physletb.2015.07.006. ISSN 0370-2693. Retrieved 23 June 2023.
  5. ↑ Kaji, D.; Morimoto, K.; Haba, H.; Ideguchi, E.; Koura, H.; Morita, K. (2016). "Decay Properties of New Isotopes 234Bk and 230Am, and Even–Even Nuclides 234Cm and 230Pu" (PDF). Journal of the Physical Society of Japan. 84 (15002): 015002. Bibcode:2016JPSJ...85a5002K. doi:10.7566/JPSJ.85.015002.
  6. ↑ Konki, J.; et al. (10 Jan 2017). "Towards saturation of the electron-capture delayed fission probability: The new isotopes 240Es and 236Bk". Physics Letters B. 764: 265–270. Bibcode:2017PhLB..764..265K. doi:10.1016/j.physletb.2016.11.038. hdl:1885/110868. ISSN 0370-2693.
  7. ↑ Antalic, S.; Heßberger, F. P.; Hofmann, S.; et al. (2010). "Studies of neutron-deficient mendelevium isotopes at SHIP". European Physical Journal A. 43 (1): 35–44. Bibcode:2010EPJA...43...35A. doi:10.1140/epja/i2009-10896-0. S2CID 121963345.
  8. ↑ Asai, M.; Tsukada, K.; Ichikawa, S.; Sakama, M.; Haba, H.; Nagame, Y.; Nishinaka, I.; Akiyama, K.; Toyoshima, A.; Kaneko, T.; Oura, Y.; Kojima, Y.; Shibata, M. (1 January 2003). "Identification of the new isotope 241Bk" (PDF). The European Physical Journal A - Hadrons and Nuclei. 16 (1): 17–19. Bibcode:2003EPJA...16...17A. doi:10.1140/epja/i2002-10112-y. ISSN 1434-601X. S2CID 122786530. Retrieved 25 June 2023.
  9. ↑ Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
  10. ↑ Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
  11. ↑ Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.
  12. ↑ Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
    "The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk248 with a half-life greater than 9 [years]. No growth of Cf248 was detected, and a lower limit for the β− half-life can be set at about 104 [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]."
  13. ↑ This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
  14. ↑ Excluding those "classically stable" nuclides with half-lives significantly in excess of 232Th; e.g., while 113mCd has a half-life of only fourteen years, that of 113Cd is nearly eight quadrillion years.
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