Thallium-188

Properties and data of the isotope ¹⁸⁸Tl.

Content

General data

Name of the isotope:Thallium-188; Tl-188Symbol:¹⁸⁸Tl or 18881TlMass number A:188 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:107Isotopic mass:187.97602(3) u (atomic weight of Thallium-188)Nuclide mass:187.93159 u (calculated nuclear mass without electrons)Mass excess:-22.33723 MeVMass defect:1.584953604 u (per nucleus)Nuclear binding energy:1476.3747724 MeV (per nucleus)
7.8530573 MeV (average binding energy per nucleon)Separation energy:S_N = 7.96(3) MeV (first neutron)
S_P = 1.51(3) MeV (first proton)Half-life:71(2) sDecay constant λ:0.0097626363459147 s^-1Specific activity α:3.143955681253 × 10⁺¹⁹ Bq g^-1
849717751.69008 Ci g^-1Spin and parity:
(nuclear angular momentum)(2-)Charge radius:5.4017(72) femtometer fmYear of discovery:1970

Radioactive Decay

Half-life T_½ = 71(2) s respectively 7.1 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹⁸⁸Hg	100 %	7.87(3) MeV

Parent Nuclides

Direct parent isotopes are: ¹⁹²Bi, ¹⁸⁸Pb.

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
^188m1Tl	35(31) keV	71.5(15) s	(7+)
^188m2Tl	303.8(2) keV	41(4) ms	9-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 107) and isobaric (same nucleon number A = 188) with Thallium-188. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 107	Isobar A = 188
65	¹⁷²Tb
66	¹⁷³Dy
67	¹⁷⁴Ho
68	¹⁷⁵Er
69	¹⁷⁶Tm
70	¹⁷⁷Yb
71	¹⁷⁸Lu	¹⁸⁸Lu
72	¹⁷⁹Hf	¹⁸⁸Hf
73	¹⁸⁰Ta	¹⁸⁸Ta
74	¹⁸¹W	¹⁸⁸W
75	¹⁸²Re	¹⁸⁸Re
76	¹⁸³Os	¹⁸⁸Os
77	¹⁸⁴Ir	¹⁸⁸Ir
78	¹⁸⁵Pt	¹⁸⁸Pt
79	¹⁸⁶Au	¹⁸⁸Au
80	¹⁸⁷Hg	¹⁸⁸Hg
81	¹⁸⁸Tl	¹⁸⁸Tl
82	¹⁸⁹Pb	¹⁸⁸Pb
83	¹⁹⁰Bi	¹⁸⁸Bi
84	¹⁹¹Po	¹⁸⁸Po
85	¹⁹²At
86	¹⁹³Rn