Thallium-197

Properties and data of the isotope ¹⁹⁷Tl.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

See also: List of individual Thallium isotopes (and general data sources).

General data

Name of the isotope:Thallium-197; Tl-197Symbol:¹⁹⁷Tl or 19781TlMass number A:197 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:116Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.4320987654321 (= neutron-proton ratio)Neutron excess (N-Z):35Isotopic mass:196.969574(18) u (atomic weight of Thallium-197)Nuclide mass:196.925144 u (calculated nuclear mass without electrons)Mass excess:-28.34164 MeVMass defect:1.669383848 u (per nucleus)Nuclear binding energy:1555.02103811 MeV (per nucleus)
7.89350781 MeV (average binding energy per nucleon)Separation energy:S_N = 8.916(20) MeV (first neutron)
S_P = 3.805(17) MeV (first proton)Half-life:2.84(4) hDecay constant λ:6.779608573551 × 10^-5 s^-1Specific activity α:2.083048867610 × 10⁺¹⁷ Bq g^-1
5629861.8043524 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Charge radius:5.4388(36) femtometer fmYear of discovery:1955

Radioactive Decay

Half-life T_½ = 2.84(4) h (hours) respectively 1.0224 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹⁹⁷Hg	100 %	2.199(17) MeV

Parent Nuclides

Direct parent isotopes are: ¹⁹⁷Pb, ²⁰¹Bi.

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
^197mTl	608.22(8) keV	0.54(1) s	9/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 116) and isobaric (same nucleon number A = 197) with Thallium-197. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 116	Isobar A = 197
71	¹⁸⁷Lu
72	¹⁸⁸Hf
73	¹⁸⁹Ta
74	¹⁹⁰W	¹⁹⁷W
75	¹⁹¹Re	¹⁹⁷Re
76	¹⁹²Os	¹⁹⁷Os
77	¹⁹³Ir	¹⁹⁷Ir
78	¹⁹⁴Pt	¹⁹⁷Pt
79	¹⁹⁵Au	¹⁹⁷Au
80	¹⁹⁶Hg	¹⁹⁷Hg
81	¹⁹⁷Tl	¹⁹⁷Tl
82	¹⁹⁸Pb	¹⁹⁷Pb
83	¹⁹⁹Bi	¹⁹⁷Bi
84	²⁰⁰Po	¹⁹⁷Po
85	²⁰¹At	¹⁹⁷At
86	²⁰²Rn	¹⁹⁷Rn
87	²⁰³Fr
88	²⁰⁴Ra
89	²⁰⁵Ac