Thallium-206

Properties and data of the isotope ²⁰⁶Tl.

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-206; Tl-206Symbol:²⁰⁶Tl or 20681TlMass number A:206 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:125Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.5432098765432 (= neutron-proton ratio)Neutron excess (N-Z):44Isotopic mass:205.9761100(14) u (atomic weight of Thallium-206)Nuclide mass:205.93168 u (calculated nuclear mass without electrons)Mass excess:-22.25339 MeVMass defect:1.740832092 u (per nucleus)Nuclear binding energy:1621.57464871 MeV (per nucleus)
7.8717216 MeV (average binding energy per nucleon)Separation energy:S_N = 6.5038(4) MeV (first neutron)
S_P = 7.255(4) MeV (first proton)Half-life:4.202(11) minDecay constant λ:0.0027492748713309 s^-1Specific activity α:8.076351481872 × 10⁺¹⁸ Bq g^-1
218279769.78034 Ci g^-1Spin and parity:
(nuclear angular momentum)0-Year of discovery:1935

Radioactive Decay

Half-life T_½ = 4.202(11) min (minutes) respectively 2.5212 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²⁰⁶Pb	100 %	1.5322(6) MeV

Parent Nuclides

Direct parent isotopes are: ²⁰⁶Hg, ²¹⁰Bi.

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
^206mTl	2643.10(18) keV	3.74(3) min	(12-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 125) and isobaric (same nucleon number A = 206) with Thallium-206. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 125	Isobar A = 206
76	²⁰¹Os
77	²⁰²Ir
78	²⁰³Pt	²⁰⁶Pt
79	²⁰⁴Au	²⁰⁶Au
80	²⁰⁵Hg	²⁰⁶Hg
81	²⁰⁶Tl	²⁰⁶Tl
82	²⁰⁷Pb	²⁰⁶Pb
83	²⁰⁸Bi	²⁰⁶Bi
84	²⁰⁹Po	²⁰⁶Po
85	²¹⁰At	²⁰⁶At
86	²¹¹Rn	²⁰⁶Rn
87	²¹²Fr	²⁰⁶Fr
88	²¹³Ra	²⁰⁶Ra
89	²¹⁴Ac	²⁰⁶Ac
90	²¹⁵Th
91	²¹⁶Pa
92	²¹⁷U