Thorium-235

Properties and data of the isotope ²³⁵Th.

Content

General data

Name of the isotope:Thorium-235; Th-235Symbol:²³⁵Th or 23590ThMass number A:235 (= number of nucleons)Atomic number Z:90 (= number of protons)Neutrons N:145Isotopic mass:235.047255(14) u (atomic weight of Thorium-235)Nuclide mass:234.9978892 u (calculated nuclear mass without electrons)Mass excess:44.01775 MeVMass defect:1.9134107 u (per nucleus)Nuclear binding energy:1782.33058659 MeV (per nucleus)
7.58438547 MeV (average binding energy per nucleon)Separation energy:S_N = 4.667(13) MeV (first neutron)
S_P = 8.112(19) MeV (first proton)Half-life:7.2(1) minDecay constant λ:0.0016045073624073 s^-1Specific activity α:4.111731637115 × 10⁺¹⁸ Bq g^-1
111127882.08421 Ci g^-1Spin and parity:
(nuclear angular momentum)(1/2+)Year of discovery:1969

Radioactive Decay

Half-life T_½ = 7.2(1) min (minutes) respectively 4.32 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²³⁵Pa	100 %	1.729(19) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 145) and isobaric (same nucleon number A = 235) with Thorium-235. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 145	Isobar A = 235
87	²³²Fr
88	²³³Ra
89	²³⁴Ac	²³⁵Ac
90	²³⁵Th	²³⁵Th
91	²³⁶Pa	²³⁵Pa
92	²³⁷U	²³⁵U
93	²³⁸Np	²³⁵Np
94	²³⁹Pu	²³⁵Pu
95	²⁴⁰Am	²³⁵Am
96	²⁴¹Cm	²³⁵Cm
97	²⁴²Bk	²³⁵Bk
98	²⁴³Cf
99	²⁴⁴Es
100	²⁴⁵Fm
101	²⁴⁶Md