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    		•
    Elements

    ASTATINE
    85
    At
    [ 210 ]


    Name: astatineGroup number: 17
    Symbol: AtGroup name: Halogen
    Atomic number: 85Period number: 6
    Atomic weight: [ 210 ]Block: p-block
    CAS Registry ID: 7440-68-8Voice:
    Standard state: solid at 298 KColour: metallic
    Classification: Semi-metallicAvailability:

    astatine
    This sample of uranite contains a vanishingly small amount of astatine. Image adapted with permission from Prof James Marshall"s (U. North Texas, USA) Walking Tour of the elements CD.

    The longest-lived isotope, 210At, has a half-life of only 8.3 hours. There are about 20 isotopes known, all of which are radioactive. Astatine is a halogen and possibly accumulates in the thyroid like iodine.

    Isolation

    Here is a brief summary of the isolation of astatine.

    Astatine is radioactive and essentially unavailable in nature. It is not possible to make other than in a nuclear reactor. Bombardment of the bismuth isotope 20983Bi with a-particles (helium nuclei, 42He) results in formation of shortlived astatine and neutrons. The bismuth target is cooled during irradiation to prevent the volatile astatine disappearing.

    20983Bi + 42He 21185At + 2 10n

    The 211At isotope has a half life of just over 7 hours so it is necessary to work quickly with it! Available quantities are of the order of 0.001 mg.

    Heating the bismuth target to 300-600°C under N2 results in a stream of the elemental astatine that can be collected on a cold glass finger.
    Fluorides
    none listed
    Chlorides
    none listed
    Bromides
    none listed
    Iodides
    none listed
    Hydrides
    none listed
    Oxides
    none listed
    Sulfides
    none listed
    Selenides
    none listed
    Tellurides
    none listed
    Nitrides
    none listed





    Our data and resources are taken from Web Elements