Thorium-217

Properties and data of the isotope ²¹⁷Th.

Content

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

General data

Name of the isotope:Thorium-217; Th-217Symbol: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-217)Nuclide 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)Separation energy:S_N = 6.164(15) MeV (first neutron)
S_P = 3.233(14) MeV (first proton)Half-life:0.252(4) msDecay constant λ:2750.5840498411 s^-1Specific activity α:7.633366172920 × 10⁺²⁴ Bq g^-1
2.063071938627 × 10⁺¹⁴ Ci g^-1Spin and parity:
(nuclear angular momentum)(9/2+)Year of discovery:1968

Radioactive Decay

Half-life T_½ = 0.252(4) ms respectively 2.52 × 10^-4 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²¹³Ra	100 %	9.435(4) MeV

Parent Nuclides

Direct parent isotope is: ²²¹U.

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
^217m1Th	673.3(1) keV	0.141(50) ms	(15/2-)

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-217. 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

External data and identifiers

Adopted Levels, Gammas:NuDat 217Th

Literature and References

[1] - S. S. Nafee, A. M. Al-Ramady, S. A. Shaheen:
Nuclear Data Evaluation for ²¹⁷Th.
In: Acta Physica Polonica A, Vol. 129, (2016), DOI 10.12693/APhysPolA.129.669.