Definition of actinium
: a radioactive trivalent metallic element that resembles lanthanum in chemical properties and that is found especially in pitchblende — see element table
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Origin and Etymology of actinium
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Medical Dictionary
actinium
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noun
ac·tin·i·um
\ak-ˈtin-ē-əm\
Medical Definition of actinium
: a radioactive trivalent metallic element that resembles lanthanum in chemical properties and that is found especially in pitchblende—symbol Ac; see element table
Learn More about actinium
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Britannica.com: Encyclopedia article about actinium
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