Thorium-220

Properties and data of the isotope ²²⁰Th.

Content

General data

Name of the isotope:Thorium-220; Th-220Symbol:²²⁰Th or 22090ThMass number A:220 (= number of nucleons)Atomic number Z:90 (= number of protons)Neutrons N:130Isotopic mass:220.015748(24) u (atomic weight of Thorium-220)Nuclide mass:219.9663822 u (calculated nuclear mass without electrons)Mass excess:14.66917 MeVMass defect:1.81494396 u (per nucleus)Nuclear binding energy:1690.60940908 MeV (per nucleus)
7.68458822 MeV (average binding energy per nucleon)Separation energy:S_N = 7.87(6) MeV (first neutron)
S_P = 4.19(6) MeV (first proton)Half-life:9.7(6) μsDecay constant λ:71458.472222675 s^-1Specific activity α:1.956059024367 × 10⁺²⁶ Bq g^-1
5.286646011803 × 10⁺¹⁵ Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1973

Radioactive Decay

Half-life T_½ = 9.7(6) μs respectively 9.7 × 10^-6 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²¹⁶Ra	≤ 100 %	8.953(20) MeV
EE	²²⁰Ac	<< 1 %	0.925(23) MeV

Parent Nuclides

Direct parent isotope is: ²²⁴U.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 130) and isobaric (same nucleon number A = 220) with Thorium-220. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 130	Isobar A = 220
78	²⁰⁸Pt
79	²⁰⁹Au
80	²¹⁰Hg
81	²¹¹Tl
82	²¹²Pb	²²⁰Pb
83	²¹³Bi	²²⁰Bi
84	²¹⁴Po	²²⁰Po
85	²¹⁵At	²²⁰At
86	²¹⁶Rn	²²⁰Rn
87	²¹⁷Fr	²²⁰Fr
88	²¹⁸Ra	²²⁰Ra
89	²¹⁹Ac	²²⁰Ac
90	²²⁰Th	²²⁰Th
91	²²¹Pa	²²⁰Pa
92	²²²U	²²⁰U