Isotopes of berkelium

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 twenty known radioisotopes, from ²³³Bk to ²⁵³Bk (except ²³⁷Bk), and seven nuclear isomers. The longest-lived isotope known is ²⁴⁷Bk with a half-life of 1,380 years; however ²⁴⁸Bk, which has not been observed to decay, may live longer.

The isotope commonly used in study, though, is ²⁴⁹Bk, as is it the only berkelium isotope that can be usefully extracted from reactor actinides and accumulated in weighable quantities.

List of isotopes

|-id=Berkelium-233 | rowspan=2|²³³Bk | rowspan=2 style="text-align:right" | 97 | rowspan=2 style="text-align:right" | 136 | rowspan=2|233.05665(25)# | rowspan=2| | α (82%) | ²²⁹Am | rowspan=2|3/2−# |- | β⁺? (18%) | ²³³Cm |-id=Berkelium-234 | rowspan=2|²³⁴Bk | rowspan=2 style="text-align:right" | 97 | rowspan=2 style="text-align:right" | 137 | rowspan=2|234.05732(16)# | rowspan=2| | α (>80%) | ²³⁰Am | rowspan=2|3−# |- | β⁺ (<20%) | ²³⁴Cm |-id=Berkelium-235 | rowspan=2|²³⁵Bk | rowspan=2 style="text-align:right" | 97 | rowspan=2 style="text-align:right" | 138 | rowspan=2|235.05665(43)# | rowspan=2|1# min | α | ²³¹Am | rowspan=2|3/2−# |- | β⁺ | ²³⁵Cm |-id=Berkelium-236 | rowspan=2|²³⁶Bk | rowspan=2 style="text-align:right" | 97 | rowspan=2 style="text-align:right" | 139 | rowspan=2|236.05748(39)# | rowspan=2| | β⁺ (99.96%) | ²³⁶Cm | rowspan=2|4+# |- | β⁺, SF (0.04%) | (various) |-id=Berkelium-238 | rowspan=2|²³⁸Bk | rowspan=2 style="text-align:right" | 97 | rowspan=2 style="text-align:right" | 141 | rowspan=2|238.05820(28)# | rowspan=2| | β⁺ (99.95%) | ²³⁸Cm | rowspan=2| 1# |- | β⁺, SF (0.048%) | (various) |-id=Berkelium-239 | ²³⁹Bk | style="text-align:right" | 97 | style="text-align:right" | 142 | 239.05824(22)# | 100#&nbsp;s | β⁺ | ²³⁹Cm | (7/2+) |-id=Berkelium-240 | rowspan=3|²⁴⁰Bk | rowspan=3 style="text-align:right" | 97 | rowspan=3 style="text-align:right" | 143 | rowspan=3|240.05976(16)# | rowspan=3| | β⁺? | ²⁴⁰Cm | rowspan=3|7−# |- | α? | ²³⁶Am |- | β⁺, SF (0.0013%) | (various) |-id=Berkelium-241 | ²⁴¹Bk | style="text-align:right" | 97 | style="text-align:right" | 144 | 241.06010(18)# | | β⁺ | ²⁴¹Cm | (7/2+) |-id=Berkelium-242 | rowspan=2|²⁴²Bk | rowspan=2 style="text-align:right" | 97 | rowspan=2 style="text-align:right" | 145 | rowspan=2|242.06200(14)# | rowspan=2| | β⁺ | ²⁴²Cm | rowspan=2|3+# |- | β⁺, SF (<3×10^{−5}%) | (various) |-id=Berkelium-242m | style="text-indent:1em" | ^242mBk | colspan="3" style="text-indent:2em" | 2000(200)#&nbsp;keV | | SF | (various) | |-id=Berkelium-243 | rowspan=2|²⁴³Bk | rowspan=2 style="text-align:right" | 97 | rowspan=2 style="text-align:right" | 146 | rowspan=2|243.063006(5) | rowspan=2| | β⁺ (99.85%) | ²⁴³Cm | rowspan=2|3/2− |- | α (0.15%) | ²³⁹Am |-id=Berkelium-244 | rowspan=2|²⁴⁴Bk | rowspan=2 style="text-align:right" | 97 | rowspan=2 style="text-align:right" | 147 | rowspan=2|244.065179(15) | rowspan=2| | β⁺ (99.994%) | ²⁴⁴Cm | rowspan=2|4− |- | α (0.006%) | ²⁴⁰Am |-id=Berkelium-244m | style="text-indent:1em" | ^244mBk | colspan="3" style="text-indent:2em" | 1500(500)#&nbsp;keV | | SF | (various) | |-id=Berkelium-245 | rowspan=2|²⁴⁵Bk | rowspan=2 style="text-align:right" | 97 | rowspan=2 style="text-align:right" | 148 | rowspan=2|245.0663598(19) | rowspan=2| | EC (99.88%) | ²⁴⁵Cm | rowspan=2|3/2− |- | α (0.12%) | ²⁴¹Am |-id=Berkelium-246 | ²⁴⁶Bk | style="text-align:right" | 97 | style="text-align:right" | 149 | 246.06867(6) | | β⁺ | ²⁴⁶Cm | 2(−) |-id=Berkelium-247 | rowspan=2|²⁴⁷Bk | rowspan=2 style="text-align:right" | 97 | rowspan=2 style="text-align:right" | 150 | rowspan=2|247.070306(6) | rowspan=2| | α | ²⁴³Am | rowspan=2|3/2− |- | SF? | (various) |-id=Berkelium-248 | rowspan=3|²⁴⁸Bk | rowspan=3 style="text-align:right" | 97 | rowspan=3 style="text-align:right" | 151 | rowspan=3|248.07314(5) | rowspan=3|>9&nbsp;y | α? | ²⁴⁴Am | rowspan=3|6+# |- | EC? | ²⁴⁸Cm |- | β^−? | ²⁴⁸Cf |-id=Berkelium-248m | rowspan=2 style="text-indent:1em" | ^248mBk | rowspan=2 colspan="3" style="text-indent:2em" | −20(50)&nbsp;keV | rowspan=2| 23.7(2)&nbsp;h | β^− (70%) | ²⁴⁸Cf | rowspan=2|1(−) |- | EC (30%) | ²⁴⁸Cm |-id=Berkelium-249 | rowspan=3|²⁴⁹Bk | rowspan=3 style="text-align:right" | 97 | rowspan=3 style="text-align:right" | 152 | rowspan=3|249.0749831(13) | rowspan=3| | β^− | ²⁴⁹Cf | rowspan=3|7/2+ |- | α (0.00145%) | ²⁴⁵Am |- | SF (4.7×10^{−8}%) | (various) |-id=Berkelium-249m | style="text-indent:1em" | ^249mBk | colspan="3" style="text-indent:2em" | 8.777(14)&nbsp;keV | | IT | ²⁴⁹Bk | 3/2− |-id=Berkelium-250 | ²⁵⁰Bk | style="text-align:right" | 97 | style="text-align:right" | 153 | 250.078317(3) | | β^− | ²⁵⁰Cf | 2− |-id=Berkelium-250m1 | style="text-indent:1em" | ^250m1Bk | colspan="3" style="text-indent:2em" | 35.59(10)&nbsp;keV | | IT | ²⁵⁰Bk | 4+ |-id=Berkelium-250m2 | style="text-indent:1em" | ^250m2Bk | colspan="3" style="text-indent:2em" | 85.6(16)&nbsp;keV | | IT | ²⁵⁰Bk | 7+ |-id=Berkelium-251 | ²⁵¹Bk | style="text-align:right" | 97 | style="text-align:right" | 154 | 251.080761(12) | | β^− | ²⁵¹Cf | (3/2−) |-id=Berkelium-251m | style="text-indent:1em" | ^251mBk | colspan="3" style="text-indent:2em" | 35.5(13)&nbsp;keV | | IT | ²⁵¹Bk | (7/2+) |-id=Berkelium-252 | ²⁵²Bk | style="text-align:right" | 97 | style="text-align:right" | 155 | 252.08431(22)# | | β^− | ²⁵²Cf | |-id=Berkelium-253 | ²⁵³Bk | style="text-align:right" | 97 | style="text-align:right" | 156 | 253.08688(39)# | 60#&nbsp;min | β^−? | ²⁵³Cf | 3/2-#

Actinides vs fission products

References

• Isotope masses from:
• Half-life, spin, and isomer data selected from the following sources.