Thorium-233

Properties and data of the isotope ²³³Th.

Content

General data

Name of the isotope:Thorium-233; Th-233Symbol:²³³Th or 23390ThMass number A:233 (= number of nucleons)Atomic number Z:90 (= number of protons)Neutrons N:143Isotopic mass:233.0415802(15) u (atomic weight of Thorium-233)Nuclide mass:232.9922144 u (calculated nuclear mass without electrons)Mass excess:38.73171 MeVMass defect:1.901755668 u (per nucleus)Nuclear binding energy:1771.47399421 MeV (per nucleus)
7.60289268 MeV (average binding energy per nucleon)Separation energy:S_N = 4.78639(9) MeV (first neutron)
S_P = 7.712(13) MeV (first proton)Cross section:σ(n.γ) = 1500(100) barn (thermal neutron capture cross-section)
σ(n.f) = 15 b (gap cross-section)Half-life:21.83(4) minDecay constant λ:0.00052920077917235 s^-1Specific activity α:1.367777525907 × 10⁺¹⁸ Bq g^-1
36966960.159659 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Year of discovery:1935

Radioactive Decay

Half-life T_½ = 21.83(4) min (minutes) respectively 1.3098 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²³³Pa	100 %	1.2422(11) MeV

Parent Nuclides

Direct parent isotope is: ²³³Ac.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 143) and isobaric (same nucleon number A = 233) with Thorium-233. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 143	Isobar A = 233
84	²²⁷Po
85	²²⁸At
86	²²⁹Rn
87	²³⁰Fr	²³³Fr
88	²³¹Ra	²³³Ra
89	²³²Ac	²³³Ac
90	²³³Th	²³³Th
91	²³⁴Pa	²³³Pa
92	²³⁵U	²³³U
93	²³⁶Np	²³³Np
94	²³⁷Pu	²³³Pu
95	²³⁸Am	²³³Am
96	²³⁹Cm	²³³Cm
97	²⁴⁰Bk	²³³Bk
98	²⁴¹Cf
99	²⁴²Es
100	²⁴³Fm
101	²⁴⁴Md