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Trace
Elements Laboratory |
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A
Joint Venture of London Health Sciences Centre and St. Joseph's
Health Care London
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Francium
(Fr)
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This element is not currently measured in this
laboratory.
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| Atomic Number: |
87
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| Atomic Symbol: |
Fr
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| Atomic Weight: |
223
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| Electron Configuration: |
[Rn]7s1 |
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.
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