Thorium-226

Properties and data of the isotope ²²⁶Th.

Content

General data

Name of the isotope:Thorium-226; Th-226Symbol:²²⁶Th or 22690ThMass number A:226 (= number of nucleons)Atomic number Z:90 (= number of protons)Neutrons N:136Isotopic mass:226.024904(5) u (atomic weight of Thorium-226)Nuclide mass:225.9755382 u (calculated nuclear mass without electrons)Mass excess:23.19793 MeVMass defect:1.857777456 u (per nucleus)Nuclear binding energy:1730.5085536 MeV (per nucleus)
7.65711749 MeV (average binding energy per nucleon)Separation energy:S_N = 7.184(7) MeV (first neutron)
S_P = 5.729(6) MeV (first proton)Half-life:30.57(10) minDecay constant λ:0.00037790163589573 s^-1Specific activity α:1.006980921488 × 10⁺¹⁸ Bq g^-1
27215700.580778 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1948

Radioactive Decay

Half-life T_½ = 30.57(10) min (minutes) respectively 1.8342 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²²²Ra	100 %	6.4525(10) MeV

Parent Nuclides

Direct parent isotopes are: ²³⁰U, ²²⁶Ac, ²²⁶Pa.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 136) and isobaric (same nucleon number A = 226) with Thorium-226. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 136	Isobar A = 226
80	²¹⁶Hg
81	²¹⁷Tl
82	²¹⁸Pb
83	²¹⁹Bi
84	²²⁰Po	²²⁶Po
85	²²¹At	²²⁶At
86	²²²Rn	²²⁶Rn
87	²²³Fr	²²⁶Fr
88	²²⁴Ra	²²⁶Ra
89	²²⁵Ac	²²⁶Ac
90	²²⁶Th	²²⁶Th
91	²²⁷Pa	²²⁶Pa
92	²²⁸U	²²⁶U
93	²²⁹Np	²²⁶Np
94	²³⁰Pu
95	²³¹Am
96	²³²Cm
97	²³³Bk