Curium-249

Properties and data of the isotope ²⁴⁹Cm.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

See also: List of individual Curium isotopes (and general data sources).

General data

Name of the isotope:Curium-249; Cm-249Symbol:²⁴⁹Cm or 24996CmMass number A:249 (= number of nucleons)Atomic number Z:96 (= number of protons)Neutrons N:153Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.59375 (= neutron-proton ratio)Neutron excess (N-Z):57Isotopic mass:249.0759540(25) u (atomic weight of Curium-249)Nuclide 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)Separation energy:S_N = 4.71337(25) MeV (first neutron)
S_P = 7.10(20) MeV (first proton)Half-life:64.15(3) minDecay constant λ:2.047762653431 × 10^-5 s^-1Specific activity α:4.952576364128 × 10⁺¹⁶ Bq g^-1
1338534.1524673 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Year of discovery:1956

Radioactive Decay

Half-life T_½ = 64.15(3) min (minutes) respectively 3.3849 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²⁴⁹Bk	100 %	0.9043(26) MeV

Parent Nuclides

Direct parent isotope is: ²⁵³Cf.

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
^249mCm	48.76(4) keV	23 μs	7/2+

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-249. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	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	²⁴⁹No
103	²⁵⁶Lr
104	²⁵⁷Rf
105	²⁵⁸Db
106	²⁵⁹Sg
107	²⁶⁰Bh