Lead-207

Properties and data of the isotope ²⁰⁷Pb.

Contents

General Data

Parent Nuclides

NMR Data

Isotones und Isobares

Literature

Lead-207 is a stable isotope of the chemical element lead, which has 125 neutrons in its atomic nucleus in addition to the element-specific 82 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 207.

The Pb isotope ²⁰⁷Pb was identified in 1927 during the mass spectrometric analysis of lead compounds [1].

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

General data

Name of the isotope:Lead-207; Pb-207Other names:Actinium DSymbol:²⁰⁷Pb or 20782PbMass number A:207 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:125Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.5243902439024 (= neutron-proton ratio)Neutron excess (N-Z):43Isotopic mass:206.975897(8) u (atomic weight of Lead-207)Nuclide mass:206.9309186 u (calculated nuclear mass without electrons)Mass excess:-22.4518 MeVMass defect:1.748870124 u (per nucleus)Nuclear binding energy:1629.06202729 MeV (per nucleus)
7.86986487 MeV (average binding energy per nucleon)Separation energy:S_N = 6.73778(10) MeV (first neutron)
S_P = 7.4876(6) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)1/2-Magnetic dipole moment:μ(μ_N) = + 0.59258Charge radius:5.4943(14) femtometer fmYear of discovery:1927

Parent Nuclides

Direct parent isotopes are: ²⁰⁷Bi, ²¹¹Po, ²⁰⁷Tl, ²²¹Ra.

Occurrence

Comparison of the natural Lead isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Lead Isotopic mixture	207.2 u	100 %
Isotope ²⁰⁶Pb	205.974466(8) u	24.1(30) %	stable	0+
Isotope ²⁰⁴Pb	203.973044(8) u	1.4(6) %	1.4 × 10¹⁷ a	0+
Isotope ²⁰⁸Pb	207.976653(8) u	52.4(70) %	stable	0+
Isotope ²⁰⁷Pb	206.975897(8) u	22.1(50) %	stable	1/2-

NMR data

Nuclear magnetic properties and parameters of the NMR active Nuclide ²⁰⁷Pb

Isotope:²⁰⁷Pb-NMRQuantity:22.1(50) %Spin:1/2-Nuclearmagnetic moment
μ/μ_N:+ 0.59258Gyromagnetic ratio γ:5.58046 · 10⁷ rad T^-1 s^-1
8.88158 MHz T^-1Nuclear g-factor:g_l = 1.18516Resonance frequency:v₀ = 9.0340 MHz at 1 TRelative Sensitivity:[related to ¹H = 1.000]:
0.00955 (H₀ = const.)
0.2122 (v₀ = const.)
0.00201 (at natural abundance)
relative receptivity as compared to ¹³C:
11.8 (at natural abundance)Reference compound:
(conditions)For calibration, a solution of a small amount of tetramethyllead (< 10 %) in benzene-d6 is used.Frequency ratio:Ξ(²⁰⁷Pb) = 20.920599 % [based on the reference substance]

²⁰⁷Pb-NMR spectroscopy utilizes the spin-1/2 nucleus ²⁰⁷Pb, which has medium NMR sensitivity and yields narrow resonance lines over an exceptionally large chemical shift range. In liquid-phase NMR, ²⁰⁷Pb is primarily used to investigate organic lead compounds, while in solid-state NMR, the temperature-dependent chemical shift of lead dinitrat (Pb(NO₃)₂) is specifically employed as an NMR thermometer. Limitations arise from the comparatively low sensitivity and strong relativistic effects, which complicate interpretation and measurement conditions.

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
^207mPb	1633.356(4) keV	806(5) ms	13/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 125) and isobaric (same nucleon number A = 207) with Lead-207. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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

External data and identifiers

Adopted Levels, Gammas:NuDat 207Pb

Literature and References

[1] - F. W. Aston:
The Constitution of Ordinary Lead.
In: Nature, 120, 224, (1927), DOI 10.1038/120224a0.

[2] - Thomas Gasevic et al.:
Benchmark Study on the Calculation of ²⁰⁷Pb NMR Chemical Shifts.
In: Inorganic Chemistry, 63, 11, (2024), DOI 10.1021/acs.inorgchem.3c04539.