Lead-201m2
Properties and data of the isotope 201m2Pb.
See also: List of individual Lead isotopes (and general data sources).
General data
Name of the isotope:Lead-201m2; Pb-201m2Symbol:201m2Pb or 201m282PbMass number A:201 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:119Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.4512195121951 (= neutron-proton ratio)Neutron excess (N-Z):37Excitation energy:2953(20) keVIsotopic mass:200.972870(15) u (atomic weight of Lead-201m2)Nuclide mass:200.9278916 u (calculated nuclear mass without electrons)Mass excess:-25.27143 MeVMass defect:1.699907628 u (per nucleus)Nuclear binding energy:1583.45375604 MeV (per nucleus)
7.87787938 MeV (average binding energy per nucleon)Half-life:508(5) nsDecay constant λ:1364462.9538582 s-1Specific activity α:4.108494053149 × 10+27 Bq g-1
1.110403798148 × 10+17 Ci g-1Spin and parity:
(nuclear angular momentum)(29/2-)Magnetic dipole moment:μ(μN) = -1.011(6)Nuclear g-factor:gl = -0.069724137931034Year of discovery:1981
Radioactive Decay
Half-life T½ = 508(5) ns respectively 5.08 × 10-7 seconds s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| Iso | 201Pb | 100 % | | |
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 |
|---|
| 201m1Pb | 629.1(3) keV | 60.8(18) s | 13/2+ |
| 201Pb | | 9.33(3) h | 5/2- |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 119) and isobaric (same nucleon number A = 201) with Lead-201m2. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 119 | Isobar A = 201 |
|---|
| 73 | 192Ta | |
| 74 | 193W | |
| 75 | 194Re | |
| 76 | 195Os | 201Os |
| 77 | 196Ir | 201Ir |
| 78 | 197Pt | 201Pt |
| 79 | 198Au | 201Au |
| 80 | 199Hg | 201Hg |
| 81 | 200Tl | 201Tl |
| 82 | 201Pb | 201Pb |
| 83 | 202Bi | 201Bi |
| 84 | 203Po | 201Po |
| 85 | 204At | 201At |
| 86 | 205Rn | 201Rn |
| 87 | 206Fr | 201Fr |
| 88 | 207Ra | 201Ra |
| 89 | 208Ac | |
| 90 | 209Th | |
| 91 | 210Pa | |
External data and identifiers
Last update: 2025-11-27
Perma link: https://www.chemlin.org/isotope/lead-201m2
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