radium

ra·di·um   (rā'dē-əm)    n.   Symbol Ra A rare, brilliant white, luminescent, highly radioactive metallic element found in very small amounts in uranium ores, having 13 isotopes with mass numbers between 213 and 230, of which radium 226 with a half-life of 1,622 years is the most common. It is used in cancer radiotherapy, as a neutron source for some research purposes, and as a constituent of luminescent paints. Atomic number 88; melting point 700°C; boiling point 1,737°C; valence 2. See Table at element. [Latin radius, ray + -ium.]

radium

A naturally occurring radioactive chemical element. Its symbol is Ra.

Note: Radium was discovered by the chemists Marie and Pierre Curie.

radium 

Main Entry: ra·di·um
Pronunciation: 'rAd-E-&m
Function: noun
often attributive : an intensely radioactive shining white metallicelement that resembles barium chemically, that occurs in combination in minute quantities in minerals (as pitchblende or carnotite) principally as the isotope of mass number 226 formed from uranium238, having a half-life of 1620 years, and emitting alpha particles and gamma rays to form radon, and that is used chiefly in luminous materials and in the treatment of cancer —symbol Ra;—see ELEMENT table

radium ra·di·um (rā'dē-əm)
n.
Symbol Ra
A luminescent, highly radioactive metallic element found in minute amounts in uranium ores, used as a neutron source for some research purposes, and formerly used in cancer radiotherapy; its most stable isotope is Ra 226 with a half-life of 1,622 years. Atomic number 88; melting point 700°C; boiling point 1,140°C; valence 2.

radium   (rā'dē-əm)  Pronunciation Key  Symbol Ra A rare, bright-white, highly radioactive element of the alkaline-earth group. It occurs naturally in very small amounts in ores and minerals containing uranium, and it is naturally luminescent. Radium is used as a source of radon gas for the treatment of disease and as a neutron source for scientific research. Its most stable isotope is Ra 226 with a half-life of 1,622 years. Atomic number 88; melting point 700°C; boiling point 1,737°C; valence 2. See Periodic Table.