Lead-197

Properties and data of the isotope ¹⁹⁷Pb.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Lead-197 is a radioisotope of the chemical element lead, which has 115 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 197. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ¹⁹⁷Pb is exclusively for academic purposes and experimental research.

A report on the first observation of the nuclide lead-197 was published in 1954 [1].

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

General data

Name of the isotope:Lead-197; Pb-197Symbol:¹⁹⁷Pb or 19782PbMass number A:197 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:115Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.4024390243902 (= neutron-proton ratio)Neutron excess (N-Z):33Isotopic mass:196.973435(5) u (atomic weight of Lead-197)Nuclide mass:196.9284566 u (calculated nuclear mass without electrons)Mass excess:-24.74514 MeVMass defect:1.664682964 u (per nucleus)Nuclear binding energy:1550.64219287 MeV (per nucleus)
7.87128017 MeV (average binding energy per nucleon)Separation energy:S_N = 7.468(9) MeV (first neutron)
S_P = 5.438(13) MeV (first proton)Half-life:8.1(17) minDecay constant λ:0.0014262287665842 s^-1Specific activity α:4.382117617787 × 10⁺¹⁸ Bq g^-1
118435611.29156 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2-Magnetic dipole moment:μ(μ_N) = - 1.075(2)Quadrupole moment Q:-0.08(2) barn (100 fm²)Nuclear g-factor:g_l = -0.71666666666667Charge radius:5.4446(23) femtometer fmYear of discovery:1954

Radioactive Decay

Half-life T_½ = 8.1(17) min (minutes) respectively 4.86 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β⁺	¹⁹⁷Tl	100 %	3.892(16) MeV

Parent Nuclides

Direct parent isotopes are: ¹⁹⁷Bi, ²⁰¹Po.

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
^197m1Pb	319.31(11) keV	42.9(9) min	13/2+
^197m2Pb	1914.10(25) keV	1.15(20) μs	21/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 115) and isobaric (same nucleon number A = 197) with Lead-197. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 115	Isobar A = 197
70	¹⁸⁵Yb
71	¹⁸⁶Lu
72	¹⁸⁷Hf
73	¹⁸⁸Ta
74	¹⁸⁹W	¹⁹⁷W
75	¹⁹⁰Re	¹⁹⁷Re
76	¹⁹¹Os	¹⁹⁷Os
77	¹⁹²Ir	¹⁹⁷Ir
78	¹⁹³Pt	¹⁹⁷Pt
79	¹⁹⁴Au	¹⁹⁷Au
80	¹⁹⁵Hg	¹⁹⁷Hg
81	¹⁹⁶Tl	¹⁹⁷Tl
82	¹⁹⁷Pb	¹⁹⁷Pb
83	¹⁹⁸Bi	¹⁹⁷Bi
84	¹⁹⁹Po	¹⁹⁷Po
85	²⁰⁰At	¹⁹⁷At
86	²⁰¹Rn	¹⁹⁷Rn
87	²⁰²Fr
88	²⁰³Ra
89	²⁰⁴Ac

External data and identifiers

Adopted Levels, Gammas:NuDat 197Pb

Literature and References

[1] - G. Andersson, E. Arbman, I. Bergström, A. H. Wapstra:
Neutron deficient isotopes of Pb and Tl-III: Mass numbers below 200.
In: The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, (1954), DOI 10.1080/14786440108561196.