Plutonium-231

Properties and data of the isotope ²³¹Pu.

Content

General data

Name of the isotope:Plutonium-231; Pu-231Symbol:²³¹Pu or 23194PuMass number A:231 (= number of nucleons)Atomic number Z:94 (= number of protons)Neutrons N:137Isotopic mass:231.041126(24) u (atomic weight of Plutonium-231)Nuclide mass:230.9895665 u (calculated nuclear mass without electrons)Mass excess:38.30862 MeVMass defect:1.8815205 u (per nucleus)Nuclear binding energy:1752.62505663 MeV (per nucleus)
7.58712146 MeV (average binding energy per nucleon)Separation energy:S_N = 6.697(27) MeV (first neutron)
S_P = 4.22(6) MeV (first proton)Half-life:8.6(5) minDecay constant λ:0.0013433084894573 s^-1Specific activity α:3.501988286519 × 10⁺¹⁸ Bq g^-1
94648332.0681 Ci g^-1Spin and parity:
(nuclear angular momentum)(3/2+)Year of discovery:1999

Radioactive Decay

Half-life T_½ = 8.6(5) min (minutes) respectively 5.16 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²²⁷U	10(4) %	6.839(20) MeV
EE/β⁺	²³¹Np	90(4) %	2.68(6) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 137) and isobaric (same nucleon number A = 231) with Plutonium-231. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 137	Isobar A = 231
82	²¹⁹Pb
83	²²⁰Bi
84	²²¹Po
85	²²²At
86	²²³Rn
87	²²⁴Fr	²³¹Fr
88	²²⁵Ra	²³¹Ra
89	²²⁶Ac	²³¹Ac
90	²²⁷Th	²³¹Th
91	²²⁸Pa	²³¹Pa
92	²²⁹U	²³¹U
93	²³⁰Np	²³¹Np
94	²³¹Pu	²³¹Pu
95	²³²Am	²³¹Am
96	²³³Cm
97	²³⁴Bk