Thallium-207

Properties and data of the isotope ²⁰⁷Tl.

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-207; Tl-207Symbol:²⁰⁷Tl or 20781TlMass number A:207 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:126Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.5555555555556 (= neutron-proton ratio)Neutron excess (N-Z):45Isotopic mass:206.977419(6) u (atomic weight of Thallium-207)Nuclide mass:206.932989 u (calculated nuclear mass without electrons)Mass excess:-21.03407 MeVMass defect:1.748188008 u (per nucleus)Nuclear binding energy:1628.42664032 MeV (per nucleus)
7.86679536 MeV (average binding energy per nucleon)Separation energy:S_N = 6.852(5) MeV (first neutron)
S_P = 7.378(21) MeV (first proton)Half-life:4.77(3) minDecay constant λ:0.0024218979055204 s^-1Specific activity α:7.080102104577 × 10⁺¹⁸ Bq g^-1
191354110.93453 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Magnetic dipole moment:μ(μ_N) = + 1.876(5)Nuclear g-factor:g_l = 3.752Charge radius:5.4853(27) femtometer fmYear of discovery:1908

Radioactive Decay

Half-life T_½ = 4.77(3) min (minutes) respectively 2.862 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	²⁰⁷Pb	100 %	1.418(5) MeV

Parent Nuclides

Direct parent isotopes are: ²⁰⁷Hg, ²¹¹Bi.

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
^207mTl	1348.18(16) keV	1.33(11) s	11/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 126) and isobaric (same nucleon number A = 207) with Thallium-207. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 126	Isobar A = 207
76	²⁰²Os
77	²⁰³Ir
78	²⁰⁴Pt	²⁰⁷Pt
79	²⁰⁵Au	²⁰⁷Au
80	²⁰⁶Hg	²⁰⁷Hg
81	²⁰⁷Tl	²⁰⁷Tl
82	²⁰⁸Pb	²⁰⁷Pb
83	²⁰⁹Bi	²⁰⁷Bi
84	²¹⁰Po	²⁰⁷Po
85	²¹¹At	²⁰⁷At
86	²¹²Rn	²⁰⁷Rn
87	²¹³Fr	²⁰⁷Fr
88	²¹⁴Ra	²⁰⁷Ra
89	²¹⁵Ac	²⁰⁷Ac
90	²¹⁶Th	²⁰⁷Th
91	²¹⁷Pa
92	²¹⁸U
93	²¹⁹Np