Americium-240m

Properties and data of the isotope ^240mAm.

Contents

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

General data

Name of the isotope:Americium-240m; Am-240mSymbol:^240mAm or 240m95AmMass number A:240 (= number of nucleons)Atomic number Z:95 (= number of protons)Neutrons N:145Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.5263157894737 (= neutron-proton ratio)Neutron excess (N-Z):50Excitation energy:3000 keVIsotopic mass:240.055298(15) u (atomic weight of Americium-240m)Nuclide mass:240.0031901 u (calculated nuclear mass without electrons)Mass excess:51.50976 MeVMass defect:1.94449286 u (per nucleus)Nuclear binding energy:1811.28343213 MeV (per nucleus)
7.5470143 MeV (average binding energy per nucleon)Half-life:0.94(4) msDecay constant λ:737.39061761696 s^-1Specific activity α:1.850279236702 × 10⁺²⁴ Bq g^-1
50007546937895 Ci g^-1Spin and parity:
(nuclear angular momentum)

Radioactive Decay

Half-life T_½ = 0.94(4) ms respectively 9.4 × 10^-4 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
SZ	div

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
²⁴⁰Am		50.8(3) h	(3-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 145) and isobaric (same nucleon number A = 240) with Americium-240m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 145	Isobar A = 240
87	²³²Fr
88	²³³Ra
89	²³⁴Ac
90	²³⁵Th
91	²³⁶Pa	²⁴⁰Pa
92	²³⁷U	²⁴⁰U
93	²³⁸Np	²⁴⁰Np
94	²³⁹Pu	²⁴⁰Pu
95	²⁴⁰Am	²⁴⁰Am
96	²⁴¹Cm	²⁴⁰Cm
97	²⁴²Bk	²⁴⁰Bk
98	²⁴³Cf	²⁴⁰Cf
99	²⁴⁴Es	²⁴⁰Es
100	²⁴⁵Fm
101	²⁴⁶Md