Thorium-217m1

Properties and data of the isotope ²¹⁷Th.

Content

General data

Name of the isotope:Thorium-217m1; Th-217m1Symbol:²¹⁷Th or 21790ThMass number A:217 (= number of nucleons)Atomic number Z:90 (= number of protons)Neutrons N:127Isotopic mass:217.013103(11) u (atomic weight of Thorium-217m1)
Excitation energy: 673.3(1) keVNuclide mass:216.9637372 u (calculated nuclear mass without electrons)Mass excess:12.20537 MeVMass defect:1.791594212 u (per nucleus)Nuclear binding energy:1668.85925891 MeV (per nucleus)
7.69059566 MeV (average binding energy per nucleon)Half-life:0.141(50) msDecay constant λ:4915937.4507798 s^-1Specific activity α:1.364261188351 × 10⁺²⁸ Bq g^-1
3.687192400950 × 10⁺¹⁷ Ci g^-1Spin and parity:
(nuclear angular momentum)(15/2-)

Radioactive Decay

Half-life T_½ = 0.141(50) ms respectively 1.41 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	²¹⁷Th	100 %

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
²¹⁷Th		0.252(4) ms	(9/2+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 127) and isobaric (same nucleon number A = 217) with Thorium-217m1. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 127	Isobar A = 217
76	²⁰³Os
77	²⁰⁴Ir
78	²⁰⁵Pt
79	²⁰⁶Au
80	²⁰⁷Hg
81	²⁰⁸Tl	²¹⁷Tl
82	²⁰⁹Pb	²¹⁷Pb
83	²¹⁰Bi	²¹⁷Bi
84	²¹¹Po	²¹⁷Po
85	²¹²At	²¹⁷At
86	²¹³Rn	²¹⁷Rn
87	²¹⁴Fr	²¹⁷Fr
88	²¹⁵Ra	²¹⁷Ra
89	²¹⁶Ac	²¹⁷Ac
90	²¹⁷Th	²¹⁷Th
91	²¹⁸Pa	²¹⁷Pa
92	²¹⁹U	²¹⁷U