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Astatine-211

Properties and data of the isotope 211At.

 

Astatine-211 is the radioisotope of the element astatine, whose atomic nucleus has 126 neutrons in addition to the element-specific 85 protons; this results in a mass number of 211: 211At.

See also: list of Astatine isotopes.

 

General data

Name of the isotope:Astatine-211; At-211Symbol:211AtMass number A:211Atomic number Z:85 (= number of protons)Neutrons N:126Isotopic mass:210.9874961(29) u (atomic weight of Astatine-211)Nuclide mass:210.9408724 u (calculated nuclear mass without electrons)Mass excess:-11.64731 MeVMass defect:1.769411036 u (per nucleus)Nuclear binding energy:1648.19576357 MeV (per nucleus)
7.81135433 MeV (average binding energy per nucleon)
Separation energy:SN = 7.746(8) MeV (first neutron)
SP = 2.9831(25) MeV (first proton)
Half-life:7.214(7) hDecay constant λ:2.668989236053 × 10-5 s-1Spin and parity:9/2-Year of discovery:1940

 

Radioactive Decay

Half-life T½ = 7.214(7) h (hours) respectively 2.59704 × 104 seconds s.

Decay modeDaughterProbabilityDecay energyγ energy
(intensity)
α207Bi41,80(8) %5,9824(13) MeV
EE211Po58,20(8) %0,785(3) MeV

 

Astatine-211 decay chain

 

Parent Nuclides

Direct parent isotopes are: 215Fr, 211Rn.

 

Radiation Protection

The German Radiation Protection Ordinance, for example, specifies the following limit values for the isotope Astatine-211 (exemption limits, clearance values and other values as a radioactive or highly radioactive source of radiation (HASS)):

Isotope:At-211+Exemption level:107 BqExemption level per gram:1000 Bq/g
Unrestricted handling of solids and liquids.
Surface contamination:10 Bq cm-2Half-life:7.2 h

 

Nuclear Isomers

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

Nuclear IsomerExcitation EnergyHalf-lifeSpin
211mAt4814,5(5) keV4,23(7) μs(39/2-)

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 126) and isobaric (same nucleon number A = 211) with Astatine-211. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

OZIsotone N = 126Isobar A = 211
76202Os
77203Ir
78204Pt
79205Au
80206Hg211Hg
81207Tl211Tl
82208Pb211Pb
83209Bi211Bi
84210Po211Po
85211At211At
86212Rn211Rn
87213Fr211Fr
88214Ra211Ra
89215Ac211Ac
90216Th211Th
91217Pa
92218U
93219Np

 

External data and identifiers

Adopted Levels, Gammas:NuDat 211At

 


Category: Isotopes

Last update: 26.11.2022



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