Berkelium-251m

Properties and data of the isotope ²⁵¹Bk.

Content

General data

Name of the isotope:Berkelium-251m; Bk-251mSymbol:²⁵¹Bk or 25197BkMass number A:251 (= number of nucleons)Atomic number Z:97 (= number of protons)Neutrons N:154Isotopic mass:251.080761(12) u (atomic weight of Berkelium-251m)
Excitation energy: 35.5(13) keVNuclide mass:251.0275563 u (calculated nuclear mass without electrons)Mass excess:75.22839 MeVMass defect:2.012664168 u (per nucleus)Nuclear binding energy:1874.78459651 MeV (per nucleus)
7.46926134 MeV (average binding energy per nucleon)Half-life:58(4) μsDecay constant λ:11950.81345793 s^-1Specific activity α:2.867310041214 × 10⁺²⁵ Bq g^-1
7.74948659787 × 10⁺¹⁴ Ci g^-1Spin and parity:
(nuclear angular momentum)(7/2+)

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
²⁵¹Bk		55.6(11) min	(3/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 154) and isobaric (same nucleon number A = 251) with Berkelium-251m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 154	Isobar A = 251
95	²⁴⁹Am
96	²⁵⁰Cm	²⁵¹Cm
97	²⁵¹Bk	²⁵¹Bk
98	²⁵²Cf	²⁵¹Cf
99	²⁵³Es	²⁵¹Es
100	²⁵⁴Fm	²⁵¹Fm
101	²⁵⁵Md	²⁵¹Md
102	²⁵⁶No	²⁵¹No
103	²⁵⁷Lr	²⁵¹Lr
104	²⁵⁸Rf
105	²⁵⁹Db
106	²⁶⁰Sg
107	²⁶¹Bh