Isotopes of berkelium

Isotopes of berkelium (97Bk)
Main isotopes 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 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
Z N Isotopic mass (Da)
Half-life
Decay
mode

Daughter
isotope

Spin and
parity
Excitation energy
230Bk 97 133 ~0.46 s α 226Am
233Bk 97 136 21+48
−17
 s
α 229Am 3/2-#
234Bk 97 137 19+6
−4
 s
β+ 234Cm 3-#
β+, SF (various)
α 230Am
236Bk 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 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 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 α 244Am 6+#
248mBk 30(70)# keV 23.7(2) h β 248Cf 1(−)
249Bk 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. ^ a b # – 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 by decay chain Half-life
range (a)
Fission products of 235U by yield
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 249Cfƒ 242mAmƒ 141–351 a

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

241Amƒ 251Cfƒ 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

232Th 238U 235Uƒ№ 0.7–14.1 Ga

See also


This page was last updated at 2023-10-28 18:43 UTC. Update now. View original page.

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