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“actinium”
A radioactive metallic chemical element found in uranium ores: Actinium is in equilibrium with its decay products as a source of alpha rays, such as pitchblende, a mineral consisting of uranium oxide and trace amounts of radium, thorium, polonium, lead, and helium. Uraninite in a massive form is called pitchblende which is the chief uranium ore.
Actinium possesses no stable isotopes and exists in nature only as a disintegration product of uranium and thorium.
The longest lived isotope of actinium is Ac 227 with a half-life of 21.6 years. Its atomic number is 89, the melting point is 1,050°C, the estimated boiling point is 3,200°C, and its specific calculated gravity is 10.07, and a valence of 3.
This entry is located in the following units:
actino-, actin-, actini-, -actinal, actis- +
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actinium
Information is located at Chemical Element: actinium.
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Chemical Elements List
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“actinium”
(Modern Latin: chemical element; from Greek, aktis, aktinos ray; radioactive metal)
(Modern Latin: some say it comes from Greek proto, "first"; plus actinium, "ray"; so, “first actinium”; radioactive metal)