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Astatine-217

Properties and data of the isotope 217At.

 

Astat-217 is the radioisotope of the element Astatine, whose atomic nucleus has 132 neutrons in addition to the element-specific 85 protons, resulting in a mass number of 217.

See also: list of Astatine isotopes.

 

General data

Name of the isotope:Astatine-217; At-217Symbol:217AtMass number A:217Atomic number Z:85 (= number of protons)Neutrons N:132Isotopic mass:217.004718(5) u (atomic weight of Astatine-217)Nuclide mass:216.9580943 u (calculated nuclear mass without electrons)Mass excess:4.39479 MeVMass defect:1.804178632 u (per nucleus)Nuclear binding energy:1680.58157064 MeV (per nucleus)
7.74461553 MeV (average binding energy per nucleon)
Separation energy:SN = 5.933(6) MeV (first neutron)
SP = 4.677(5) MeV (first proton)
Half-life:32.6(3) msDecay constant λ:21.262183452759 s-1Spin and parity:9/2-Year of discovery:1947

 

Radioactive Decay

Half-life T½ = 32.6(3) ms respectively 3.26 × 10-2 seconds s.

Decay modeDaughterProbabilityDecay energyγ energy
(intensity)
α213Bi99,993(3) %7,2013(12) MeV
β-217Rn0,007(3) %0,736(6) MeV

 

The figure shows the radioactive decay cascade of the At-217 nuclide. The isotope is an unstable intermediate in the so-called neptunium series, which starts from Neptunium-237 (complete decay series: see there).

 

Astatine-217 radioactive decay chain

 

Parent Nuclides

Direct parent isotope is: 221Fr.

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 132) and isobaric (same nucleon number A = 217) with Astatine-217. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

OZIsotone N = 132Isobar A = 217
80212Hg
81213Tl217Tl
82214Pb217Pb
83215Bi217Bi
84216Po217Po
85217At217At
86218Rn217Rn
87219Fr217Fr
88220Ra217Ra
89221Ac217Ac
90222Th217Th
91223Pa217Pa
92224U217U
93225Np

 

External data and identifiers

Adopted Levels, Gammas:NuDat 217At

 


Category: Isotopes

Last update: 26.11.2022



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