Plutonium-229

Properties and data of the isotope ²²⁹Pu.

Content

General data

Name of the isotope:Plutonium-229; Pu-229Symbol:²²⁹Pu or 22994PuMass number A:229 (= number of nucleons)Atomic number Z:94 (= number of protons)Neutrons N:135Isotopic mass:229.040150(70) u (atomic weight of Plutonium-229)Nuclide mass:228.9885905 u (calculated nuclear mass without electrons)Mass excess:37.39948 MeVMass defect:1.865166668 u (per nucleus)Nuclear binding energy:1737.39156024 MeV (per nucleus)
7.58686271 MeV (average binding energy per nucleon)Separation energy:S_N = 6.784(65) MeV (first neutron)
S_P = 3.719(117) MeV (first proton)Half-life:90(+71-27) sDecay constant λ:0.0077016353395549 s^-1Specific activity α:2.025342046579 × 10⁺¹⁹ Bq g^-1
547389742.31873 Ci g^-1Spin and parity:
(nuclear angular momentum)(3/2+)Year of discovery:1994

Radioactive Decay

Half-life T_½ = 90(+71-27) s respectively 9 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²²⁵U	100 %	7.598(60) MeV

Parent Nuclides

Direct parent isotope is: ²³³Cm.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 135) and isobaric (same nucleon number A = 229) with Plutonium-229. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 135	Isobar A = 229
80	²¹⁵Hg
81	²¹⁶Tl
82	²¹⁷Pb
83	²¹⁸Bi
84	²¹⁹Po
85	²²⁰At	²²⁹At
86	²²¹Rn	²²⁹Rn
87	²²²Fr	²²⁹Fr
88	²²³Ra	²²⁹Ra
89	²²⁴Ac	²²⁹Ac
90	²²⁵Th	²²⁹Th
91	²²⁶Pa	²²⁹Pa
92	²²⁷U	²²⁹U
93	²²⁸Np	²²⁹Np
94	²²⁹Pu	²²⁹Pu
95	²³⁰Am	²²⁹Am