Curium-249m

Properties and data of the isotope ²⁴⁹Cm.

Content

General data

Name of the isotope:Curium-249m; Cm-249mSymbol:²⁴⁹Cm or 24996CmMass number A:249 (= number of nucleons)Atomic number Z:96 (= number of protons)Neutrons N:153Isotopic mass:249.0759540(25) u (atomic weight of Curium-249m)
Excitation energy: 48.76(4) keVNuclide mass:249.0232977 u (calculated nuclear mass without electrons)Mass excess:70.7507 MeVMass defect:2.00098122 u (per nucleus)Nuclear binding energy:1863.90200054 MeV (per nucleus)
7.4855502 MeV (average binding energy per nucleon)Half-life:23 μsDecay constant λ:30136.833937389 s^-1Specific activity α:7.288685102147 × 10⁺²⁵ Bq g^-1
1.969914892472 × 10⁺¹⁵ 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
²⁴⁹Cm		64.15(3) min	1/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 153) and isobaric (same nucleon number A = 249) with Curium-249m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 153	Isobar A = 249
94	²⁴⁷Pu
95	²⁴⁸Am	²⁴⁹Am
96	²⁴⁹Cm	²⁴⁹Cm
97	²⁵⁰Bk	²⁴⁹Bk
98	²⁵¹Cf	²⁴⁹Cf
99	²⁵²Es	²⁴⁹Es
100	²⁵³Fm	²⁴⁹Fm
101	²⁵⁴Md	²⁴⁹Md
102	²⁵⁵No
103	²⁵⁶Lr
104	²⁵⁷Rf
105	²⁵⁸Db
106	²⁵⁹Sg
107	²⁶⁰Bh