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Astatine-216

Properties and data of the isotope 216At.

 

See also: list of Astatine isotopes.

 

General data

Name of the isotope:Astatine-216; At-216Symbol:216AtMass number A:216Atomic number Z:85 (= number of protons)Neutrons N:131Isotopic mass:216.002423(4) u (atomic weight of Astatine-216)Nuclide mass:215.9557993 u (calculated nuclear mass without electrons)Mass excess:2.25701 MeVMass defect:1.797808716 u (per nucleus)Nuclear binding energy:1674.6480321 MeV (per nucleus)
7.75300015 MeV (average binding energy per nucleon)
Separation energy:SN = 4.559(8) MeV (first neutron)
SP = 4.491(4) MeV (first proton)
Half-life:0.30(3) msDecay constant λ:2310.4906018665 s-1Spin and parity:1-Year of discovery:1948

 

Radioactive Decay

Half-life T½ = 0.30(3) ms respectively 3.0 × 10-4 seconds s.

Decay modeDaughterProbabilityDecay energyγ energy
(intensity)
α212Bi> 99 %7,950(3) MeV
EE216Po<< 1 %0,474(4) MeV
β-216Rn<< 1%2,004(7) MeV

 

At-216 is a radioactive intermediate product of the thorium series starting from Thorium-232 (see there for the complete decay series).

 

Astatine-216 decay chain

 

Parent Nuclides

Direct parent isotope is: 220Fr.

 

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear IsomerExcitation EnergyHalf-lifeSpin
216mAt413 keV0,1 ms(9-)

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 131) and isobaric (same nucleon number A = 216) with Astatine-216. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

OZIsotone N = 131Isobar A = 216
79210Au
80211Hg216Hg
81212Tl216Tl
82213Pb216Pb
83214Bi216Bi
84215Po216Po
85216At216At
86217Rn216Rn
87218Fr216Fr
88219Ra216Ra
89220Ac216Ac
90221Th216Th
91222Pa216Pa
92223U216U

 

External data and identifiers

CAS:15755-37-0InChI Key:RYXHOMYVWAEKHL-LZFNBGRKSA-NSMILES:[216At]Adopted Levels, Gammas:NuDat 216At

 


Category: Isotopes

Last update: 03.12.2022



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