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Neutron source. | Atomic Number: | 89 | Atomic Symbol: | Ac | | Atomic Weight: | 227 | Electron Configuration: | 2-8-18-9-2 | | Shells: | 2,8,18,18,32,18,9,2 | Filling Orbital: | 6d1 | | Melting Point: | 1050oC | Boiling Point: | 3200oC | | Description: | Silvery-white radioactive metal. |
History(Gr. aktis, aktinos, beam or ray). Disovered by Andre Debierne
in 1899 and independently by F. Giesel in 1902.
OccurenceOccurs naturally in association with uranium minerals.
Properties- Actinium-227, a decay product of uranium-235, is a beta emitter with a
21.6-year half-life.
- Its principal decay products are thorium-227 (18.5-day half-life),
radium-223 (11.4-day half-life), and a number of short-lived products including
radon, bismuth, polonium, and lead isotopes.
- In equilibrium with its decay products, it is a powerful source of alpha
rays. Actinium metal has been prepared by the reduction of actinium fluoride
with lithium vapor at about 1100 to 1300-degrees C.
- The chemical behavior of actinium is similar to that of the rare earths,
particularly lanthanum. Purified actinium comes into equilibrium with its decay
products at the end of 185 days, and then decays according to its 21.6-year
half-life.
- It is about 150 times as active as radium, making it of value in the
production of neutrons.
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