polonium

[puh-loh-nee-uhm]
noun Chemistry.
a radioactive element discovered by Pierre and Marie Curie in 1898; Symbol: Po; atomic number: 84; atomic weight: about 210.

Origin:
1895–1900; < Neo-Latin, equivalent to polon- (< Medieval Latin Polonia Poland) + -ium -ium

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World English Dictionary
polonium (pəˈləʊnɪəm)
 
n
a very rare radioactive element that occurs in trace amounts in uranium ores. The isotope polonium-210 is produced artificially and is used as a lightweight power source in satellites and to eliminate static electricity in certain industries. Symbol: Po; atomic no: 84; half-life of most stable isotope, 209Po: 103 years; valency: --2, 0, 2, 4, or 6; relative density (alpha modification): 9.32; melting pt: 254°C; boiling pt: 962°C
 
[C19: New Latin, from Medieval Latin Polōnia Poland; named in honour of the Polish nationality of its discoverer, Marie Curie]

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Medical Dictionary

polonium po·lo·ni·um (pə-lō'nē-əm)
n.
Symbol Po
A naturally radioactive metallic element, occurring in minute quantities in uranium ores; its most readily available isotope is Po 210, with a half-life of 138.39 days. Atomic number 84; melting point 254°C; boiling point 962°C; specific gravity 9.32; valence 2, 4.

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American Heritage
Science Dictionary
polonium   (pə-lō'nē-əm)  Pronunciation Key 
Symbol Po
A very rare, naturally radioactive, silvery-gray or black metalloid element. It is produced in extremely small amounts by the radioactive decay of radium or the bombardment of bismuth or lead with neutrons. Atomic number 84; melting point 254°C; boiling point 962°C; specific gravity 9.32; valence 2, 4. See Periodic Table.
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Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica
Encyclopedia

polonium

a radioactive, silvery-gray or black metallic element of the oxygen family (Group VIa in the periodic table). The first element to be discovered by radiochemical analysis, polonium was discovered in 1898 by Pierre and Marie Curie, who were investigating the radioactivity of a certain pitchblende, a uranium ore. Polonium is a very rare element (its abundance in the Earth's crust is about one part in 1015) that occurs in nature as a radioactive decay product of uranium, thorium, and actinium. The half-lives of its isotopes range from a fraction of a second up to 103 years; the most common natural isotope of polonium, polonium-210, has a half-life of 138.4 days.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
In her work, she established the nature of radiation and beta rays, and
  discovered and isolated polonium and radium.
Polonium haloes have only ever been found along cracks in rock.
They studied the properties of uranium and thorium and soon discovered polonium.
Polonium a radioactive chemical element and a product of radium decay.
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