Lead-185
Properties and data of the isotope 185Pb.
See also: List of individual Lead isotopes (and general data sources).
General data
Name of the isotope:Lead-185; Pb-185Symbol:185Pb or 18582PbMass number A:185 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:103Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.2560975609756 (= neutron-proton ratio)Neutron excess (N-Z):21Isotopic mass:184.987610(17) u (atomic weight of Lead-185)Nuclide mass:184.9426316 u (calculated nuclear mass without electrons)Mass excess:-11.54121 MeVMass defect:1.546528972 u (per nucleus)Nuclear binding energy:1440.58245824 MeV (per nucleus)
7.78693221 MeV (average binding energy per nucleon)Separation energy:SN = 8.561(21) MeV (first neutron)
SP = 1.947(19) MeV (first proton)Half-life:6.3(4) sDecay constant λ:0.11002336199364 s-1Specific activity α:3.600957520703 × 10+20 Bq g-1
9732317623.5241 Ci g-1Spin and parity:
(nuclear angular momentum)3/2-Magnetic dipole moment:μ(μN) = - 1.10(4)Nuclear g-factor:gl = -0.73333333333333Charge radius:5.3984(28) femtometer fmYear of discovery:1975
Radioactive Decay
Half-life T½ = 6.3(4) s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| α | 181Hg | 34(25) % | 6.695(5) MeV | |
| β+ | 185Tl | ?8.217(26) MeV | | |
Parent Nuclides
Direct parent isotopes are: 185Bi, 189Po.
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 |
|---|
| 185mPb | +x keV | 4.3(2) s | 13/2+ |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 103) and isobaric (same nucleon number A = 185) with Lead-185. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 103 | Isobar A = 185 |
|---|
| 60 | 163Nd | |
| 62 | 165Sm | |
| 63 | 166Eu | |
| 64 | 167Gd | |
| 65 | 168Tb | |
| 66 | 169Dy | |
| 67 | 170Ho | |
| 68 | 171Er | |
| 69 | 172Tm | |
| 70 | 173Yb | 185Yb |
| 71 | 174Lu | 185Lu |
| 72 | 175Hf | 185Hf |
| 73 | 176Ta | 185Ta |
| 74 | 177W | 185W |
| 75 | 178Re | 185Re |
| 76 | 179Os | 185Os |
| 77 | 180Ir | 185Ir |
| 78 | 181Pt | 185Pt |
| 79 | 182Au | 185Au |
| 80 | 183Hg | 185Hg |
| 81 | 184Tl | 185Tl |
| 82 | 185Pb | 185Pb |
| 83 | 186Bi | 185Bi |
| 84 | 187Po | |
| 85 | 188At | |
External data and identifiers
Last update: 2020-10-22
Perma link: https://www.chemlin.org/isotope/lead-185
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