Thorium-237

Properties and data of the isotope ²³⁷Th.

Content

General data

Name of the isotope:Thorium-237; Th-237Symbol:²³⁷Th or 23790ThMass number A:237 (= number of nucleons)Atomic number Z:90 (= number of protons)Neutrons N:147Isotopic mass:237.053629(17) u (atomic weight of Thorium-237)Nuclide mass:237.0042632 u (calculated nuclear mass without electrons)Mass excess:49.95509 MeVMass defect:1.924366532 u (per nucleus)Nuclear binding energy:1792.53587836 MeV (per nucleus)
7.56344252 MeV (average binding energy per nucleon)Separation energy:S_N = 4.371(21) MeV (first neutron)
S_P = 8.55(4) MeV (first proton)Half-life:4.8(5) minDecay constant λ:0.0024067610436109 s^-1Specific activity α:6.115550219760 × 10⁺¹⁸ Bq g^-1
165285141.07462 Ci g^-1Spin and parity:
(nuclear angular momentum)(5/2+)Year of discovery:1993

Radioactive Decay

Half-life T_½ = 4.8(5) min (minutes) respectively 2.88 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²³⁷Pa	100 %	2.427(21) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 147) and isobaric (same nucleon number A = 237) with Thorium-237. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 147	Isobar A = 237
89	²³⁶Ac
90	²³⁷Th	²³⁷Th
91	²³⁸Pa	²³⁷Pa
92	²³⁹U	²³⁷U
93	²⁴⁰Np	²³⁷Np
94	²⁴¹Pu	²³⁷Pu
95	²⁴²Am	²³⁷Am
96	²⁴³Cm	²³⁷Cm
97	²⁴⁴Bk	²³⁷Bk
98	²⁴⁵Cf	²³⁷Cf
99	²⁴⁶Es
100	²⁴⁷Fm
101	²⁴⁸Md