Curium-240

Properties and data of the isotope ²⁴⁰Cm.

Content

General data

Name of the isotope:Curium-240; Cm-240Symbol:²⁴⁰Cm or 24096CmMass number A:240 (= number of nucleons)Atomic number Z:96 (= number of protons)Neutrons N:144Isotopic mass:240.0555283(20) u (atomic weight of Curium-240)Nuclide mass:240.002872 u (calculated nuclear mass without electrons)Mass excess:51.72428 MeVMass defect:1.943422676 u (per nucleus)Nuclear binding energy:1810.28656216 MeV (per nucleus)
7.54286068 MeV (average binding energy per nucleon)Separation energy:S_N = 7.49(5) MeV (first neutron)
S_P = 4.9551(23) MeV (first proton)Half-life:27(1) dDecay constant λ:2.971055210286 × 10^-7 s^-1Specific activity α:7.455047074582 × 10⁺¹⁴ Bq g^-1
20148.775877249 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1949

Radioactive Decay

Half-life T_½ = 27(1) d respectively 2.333 × 10⁶ seconds s.

Decay mode	Daughter	Probability	Decay energy
α	²³⁶Pu	> 99.5 %	6.3978(6) MeV
EE	²⁴⁰Am	< 0.5 %	0.214(14) MeV
SZ	^div	trace

Parent Nuclides

Direct parent isotopes are: ²⁴⁴Cf, ²⁴⁰Bk.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 144) and isobaric (same nucleon number A = 240) with Curium-240. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 144	Isobar A = 240
85	²²⁹At
86	²³⁰Rn
87	²³¹Fr
88	²³²Ra
89	²³³Ac
90	²³⁴Th
91	²³⁵Pa	²⁴⁰Pa
92	²³⁶U	²⁴⁰U
93	²³⁷Np	²⁴⁰Np
94	²³⁸Pu	²⁴⁰Pu
95	²³⁹Am	²⁴⁰Am
96	²⁴⁰Cm	²⁴⁰Cm
97	²⁴¹Bk	²⁴⁰Bk
98	²⁴²Cf	²⁴⁰Cf
99	²⁴³Es	²⁴⁰Es
100	²⁴⁴Fm
101	²⁴⁵Md