Thallium-187
Properties and data of the isotope 187Tl.
See also: List of individual Thallium isotopes (and general data sources).
General data
Name of the isotope:Thallium-187; Tl-187Symbol:187Tl or 18781TlMass number A:187 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:106Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.3086419753086 (= neutron-proton ratio)Neutron excess (N-Z):25Isotopic mass:186.975905(9) u (atomic weight of Thallium-187)Nuclide mass:186.931475 u (calculated nuclear mass without electrons)Mass excess:-22.44435 MeVMass defect:1.576403688 u (per nucleus)Nuclear binding energy:1468.41057695 MeV (per nucleus)
7.85246298 MeV (average binding energy per nucleon)Separation energy:SN = 10.629(24) MeV (first neutron)
SP = 1.194(24) MeV (first proton)Half-life:ca. 51 sDecay constant λ:0.01359112118745 s-1Specific activity α:4.40041108791 × 10+19 Bq g-1
1189300294.0322 Ci g-1Spin and parity:
(nuclear angular momentum)(1/2+)Magnetic dipole moment:μ(μN) = 1.55(6)Nuclear g-factor:gl = 3.1Year of discovery:1976
Radioactive Decay
Half-life T½ = ca. 51 s respectively 5.1 × 101 seconds s.
Decay
mode | Daughter | Probability | Decay energy | γ energy
(intensity) |
|---|
| EC/β+ | 187Hg | ca. 100 % | 5.673(16) MeV | |
| α | 183Au | 0.03 % | 5.322(7) MeV | |
Parent Nuclides
Direct parent isotopes are: 191Bi, 187Pb.
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 |
|---|
| 187mTl | 334(4) keV | 15.60(12) s | (9/2-) |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 106) and isobaric (same nucleon number A = 187) with Thallium-187. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
| Z | Isotone N = 106 | Isobar A = 187 |
|---|
| 64 | 170Gd | |
| 65 | 171Tb | |
| 66 | 172Dy | |
| 67 | 173Ho | |
| 68 | 174Er | |
| 69 | 175Tm | |
| 70 | 176Yb | |
| 71 | 177Lu | 187Lu |
| 72 | 178Hf | 187Hf |
| 73 | 179Ta | 187Ta |
| 74 | 180W | 187W |
| 75 | 181Re | 187Re |
| 76 | 182Os | 187Os |
| 77 | 183Ir | 187Ir |
| 78 | 184Pt | 187Pt |
| 79 | 185Au | 187Au |
| 80 | 186Hg | 187Hg |
| 81 | 187Tl | 187Tl |
| 82 | 188Pb | 187Pb |
| 83 | 189Bi | 187Bi |
| 84 | 190Po | 187Po |
| 85 | 191At | |
External data and identifiers
Last update: 2020-10-22
Perma link: https://www.chemlin.org/isotope/thallium-187
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