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Astatine-195

Properties and data of the isotope 195At.


Contents

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-1
Spin 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
DaughterProbabilityDecay energyγ energy
(intensity)
α191Bi100 %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 IsomerExcitation EnergyHalf-lifeSpin
195mAt33.0(10) keV143(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.

 

ZIsotone N = 110Isobar A = 195
69179Tm
70180Yb
71181Lu
72182Hf
73183Ta
74184W195W
75185Re195Re
76186Os195Os
77187Ir195Ir
78188Pt195Pt
79189Au195Au
80190Hg195Hg
81191Tl195Tl
82192Pb195Pb
83193Bi195Bi
84194Po195Po
85195At195At
86196Rn195Rn

 

External data and identifiers

Adopted Levels, Gammas:NuDat 195At

 


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Last update: 2020-10-23


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