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radium :
A rare radioactive metallic element found in very small amounts in uranium ores. Radium is very unstable and gives off energetic particles and gamma rays as it undergoes radioactive decay. Because of the radiation, radium is dangerous to handle. A piece of radium is always one or two degrees hotter that its surroundings. Radium has an atomic number of 88, an atomic weight of 226, and its chemical symbol is Ra.
