Astatine-195
Properties and data of the isotope 195At.
See also: list of Astatine isotopes.
General data
Name of the isotope:Astatine-195; At-195Symbol:195At or 19585AtMass number A:195 (= number of nucleons)Atomic number Z:85 (= number of protons)Neutrons N:110Isotopic mass:194.996274(10) u (atomic weight of Astatine-195)Nuclide mass:194.9496503 u (calculated nuclear mass without electrons)Mass excess:-3.47075 MeVMass defect:1.62199448 u (per nucleus)Nuclear binding energy:1510.87812615 MeV (per nucleus)
7.74809295 MeV (average binding energy per nucleon)Separation energy:SN = 10.821(27) MeV (first neutron)
SP = -245(16) MeV (first proton)Half-life:290(20) msDecay constant λ:2.390162691586 s-1Specific activity α:7.41953423035 × 10+21 Bq g-1
200527952171.86 Ci g-1Spin and parity:
(nuclear angular momentum)(1/2+)Year of discovery:1999
Radioactive Decay
Half-life T½ = 290(20) ms respectively 2.90 × 10-1 seconds s.
Decay mode | Daughter | Probability | Decay energy | γ energy (intensity) |
---|
α | 191Bi | 100 % | 7.344(6) MeV | |
Parent Nuclides
Direct parent isotope is: 199Fr.
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 |
---|
195mAt | 33.0(10) keV | 143(3) ms | (7/2-) |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 110) and isobaric (same nucleon number A = 195) with Astatine-195. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
Z | Isotone N = 110 | Isobar A = 195 |
69 | 179Tm | |
70 | 180Yb | |
71 | 181Lu | |
72 | 182Hf | |
73 | 183Ta | |
74 | 184W | 195W |
75 | 185Re | 195Re |
76 | 186Os | 195Os |
77 | 187Ir | 195Ir |
78 | 188Pt | 195Pt |
79 | 189Au | 195Au |
80 | 190Hg | 195Hg |
81 | 191Tl | 195Tl |
82 | 192Pb | 195Pb |
83 | 193Bi | 195Bi |
84 | 194Po | 195Po |
85 | 195At | 195At |
86 | 196Rn | 195Rn |
External data and identifiers
Last update: 2020-10-23
Perma link: https://www.chemlin.org/isotope/astatine-195
© 1996 - 2025 ChemLin