Thallium-198

Properties and data of the isotope ¹⁹⁸Tl.

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-198; Tl-198Symbol:¹⁹⁸Tl or 19881TlMass number A:198 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:117Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.4444444444444 (= neutron-proton ratio)Neutron excess (N-Z):36Isotopic mass:197.970447(8) u (atomic weight of Thallium-198)Nuclide mass:197.926017 u (calculated nuclear mass without electrons)Mass excess:-27.52844 MeVMass defect:1.677175764 u (per nucleus)Nuclear binding energy:1562.27916111 MeV (per nucleus)
7.89029879 MeV (average binding energy per nucleon)Separation energy:S_N = 7.258(18) MeV (first neutron)
S_P = 4.277(8) MeV (first proton)Half-life:5.3(5) hDecay constant λ:3.632846858280 × 10^-5 s^-1Specific activity α:1.110533781885 × 10⁺¹⁷ Bq g^-1
3001442.6537446 Ci g^-1Spin and parity:
(nuclear angular momentum)2-Magnetic dipole moment:μ(μ_N) = 0.00(1)Charge radius:5.4396(36) femtometer fmYear of discovery:1949

Radioactive Decay

Half-life T_½ = 5.3(5) h (hours) respectively 1.9080 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹⁹⁸Hg	100 %	3.426(8) MeV

Parent Nuclides

Direct parent isotope is: ¹⁹⁸Pb.

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
^198m1Tl	543.6(4) keV	1.87(3) h	7+
^198m2Tl	686.8(5) keV	150(40) ns	(5,7,9)+
^198m3Tl	742.4(4) keV	32.1(10) ms	(10-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 117) and isobaric (same nucleon number A = 198) with Thallium-198. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 117	Isobar A = 198
71	¹⁸⁸Lu
72	¹⁸⁹Hf
73	¹⁹⁰Ta
74	¹⁹¹W
75	¹⁹²Re	¹⁹⁸Re
76	¹⁹³Os	¹⁹⁸Os
77	¹⁹⁴Ir	¹⁹⁸Ir
78	¹⁹⁵Pt	¹⁹⁸Pt
79	¹⁹⁶Au	¹⁹⁸Au
80	¹⁹⁷Hg	¹⁹⁸Hg
81	¹⁹⁸Tl	¹⁹⁸Tl
82	¹⁹⁹Pb	¹⁹⁸Pb
83	²⁰⁰Bi	¹⁹⁸Bi
84	²⁰¹Po	¹⁹⁸Po
85	²⁰²At	¹⁹⁸At
86	²⁰³Rn	¹⁹⁸Rn
87	²⁰⁴Fr
88	²⁰⁵Ra
89	²⁰⁶Ac
90	²⁰⁷Th