polonium(redirected from Element 84)
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Related to Element 84: Element 88, Element 94, Element 82, Element 83, Element 89, Element 86, Element 85
n. Symbol Po
A radioactive metallic element, occurring naturally in small quantities as a product of radium disintegration and produced synthetically by bombarding bismuth or lead with neutrons. Most isotopes decay by alpha-particle emission; the most stable are Po-208 and Po-209, with half-lives of 2.9 years and 102 years, respectively. Po-210, with a half-life of 138.4 days, is the most readily available isotope and is extremely toxic. Atomic number 84; melting point 254°C; boiling point 962°C; specific gravity 9.20; valence 2, 4, 6. See Periodic Table.
[From Medieval Latin Polōnia, Poland (the native country of Marie Curie, who discovered this element along with her husband Pierre).]
(Elements & Compounds) 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]
po•lo•ni•um(pəˈloʊ ni əm)
a radioactive chemical element discovered by Pierre and Marie Curie in 1898. Symbol: Po; at. no.: 84; at. wt.: about 210.
[< French, =polon- (< Medieval Latin Polonia Poland) + -ium -ium2]
Symbol Po A very rare, naturally radioactive, silvery-gray or black metallic 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. See Periodic Table.
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|Noun||1.||polonium - a radioactive metallic element that is similar to tellurium and bismuth; occurs in uranium ores but can be produced by bombarding bismuth with neutrons in a nuclear reactor|