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  • Elements

    FRANCIUM
    87
    Fr
    [ 223 ]


    Name: franciumGroup number: 1
    Symbol: FrGroup name: Alkali metal
    Atomic number: 87Period number: 7
    Atomic weight: [ 223 ]Block: s-block
    CAS Registry ID: 7440-73-5Voice:
    Standard state: solid at 298 KColour: metallic
    Classification: MetallicAvailability:

    francium
    This sample of uraninite contains some francium because of a steady-state decay chain. An estimate suggests there is about 10-20 grammes of francium (about 1 atom!) at any one time. Image adapted with permission from Prof James Marshall"s (U. North Texas, USA) Walking Tour of the elements CD.

    Francium occurs as a result of a disintegration of actinium. Francium is found in uranium minerals, and can be made artificially by bombarding thorium with protons. It is the most unstable of the first 101 elements. The longest lived isotope, 223Fr, a daughter of 227Ac, has a half-life of 22 minutes. This is the only isotope of francium occurring in nature, but at most there is only 20-30 g of the element present in the earth"s crust at any one time. No weighable quantity of the element has been prepared or isolated. There are about 20 known isotopes.

    Isolation

    Here is a brief summary of the isolation of francium.

    Francium is vanishingly rare and is found only as very small traces in some uranium minerals. It has never been isolated as the pure element. As it is so radioactive, any amount formed would decompose to other elements.

    Actinium decays by b decay most of the time but about 1% of the decay is by a decay. The "daughter" element of this reaction, which used to be called actinium-K, is now recognized as 22387Fr - the longest-lived isotope of actinium with a half life of about 22 minutes.

    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