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Neptunium-231

Properties and data of the isotope 231Np.

 

Neptunium-231 is the very short-lived radioisotope of the element Neptunium, whose atomic nucleus has 138 neutrons in addition to the element-specific 93 protons, resulting in a mass number of 231: 231Np.

See also: list of Neptunium isotopes.

 

General data

Name of the isotope:Neptunium-231; Np-231Symbol:231NpMass number A:231Atomic number Z:93 (= number of protons)Neutrons N:138Isotopic mass:231.03824(5) u (atomic weight of Neptunium-231)Nuclide mass:230.9872289 u (calculated nuclear mass without electrons)Mass excess:35.62033 MeVMass defect:1.885246384 u (per nucleus)Nuclear binding energy:1756.09569522 MeV (per nucleus)
7.60214587 MeV (average binding energy per nucleon)
Separation energy:SN = 7.68(7) MeV (first neutron)
SP = 3.28(5) MeV (first proton)
Half-life:48.8(2) minDecay constant λ:0.00023673059445353 s-1Spin and parity:(5/2-)Year of discovery:1950

 

Radioactive Decay

Half-life T½ = 48.8(2) min (minutes) respectively 2.928 × 103 seconds s.

Decay modeDaughterProbabilityDecay energyγ energy
(intensity)
α227Pa2(1) %6,37(5) MeV
EE231U98(1) %1,82(5) MeV

 

Neptunium-231 radioactive decay chain

 

Parent Nuclides

Direct parent isotopes are: 235Am, 231Pu.

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 138) and isobaric (same nucleon number A = 231) with Neptunium-231. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

OZIsotone N = 138Isobar A = 231
82220Pb
83221Bi
84222Po
85223At
86224Rn
87225Fr231Fr
88226Ra231Ra
89227Ac231Ac
90228Th231Th
91229Pa231Pa
92230U231U
93231Np231Np
94232Pu231Pu
95233Am231Am
96234Cm
97235Bk

 

External data and identifiers

Adopted Levels, Gammas:NuDat 231Np

 


Category: Isotopes

Last update: 26.11.2022



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