Dictionary  ra•donPronunciation: (rā'don), [key] —n. Chem. a chemically inert, radioactive gaseous element produced by the decay of radium: emissions produced by outgassing of rock, brick, etc. are a health hazard. Symbol: Rn; at. no.: 86; at. wt.: 222. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
|
Atlas
Encyclopedia
Dictionary
Thesaurus
Day in History
