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Radium. A radioactive element of the alkaline earth series of metals. It has the atomic symbol Ra, atomic number 88, and atomic weight 226. Radium is the product of the disintegration of uranium and is present in pitchblende and all ores containing uranium. It is used clinically as a source of beta and gamma-rays in radiotherapy, particularly BRACHYTHERAPY.

A chemical element, extracted from pitch-blende, which gives off invisible rays with extremely slow loss of power or weight.

A metallic chemical element discovered in 1898 by M. and Mme. Curie of Paris. It is found in pitchblende and is capable of maintaining itself at a higher temperature than the surrounding atmosphere and of giving forth powerful invisible radiations.

A substance contained in minute quantities in pitchblende and in other minerals, capable of emitting rays or particles (a, b, y,) due to the disintegration of the molecule, which perhaps have therapeutic properties. The metal has properties which resemble barium. Atomic weight, 225. Symbol, Ra. Used only in the form of its salts, the emanations of which are employed in the treatment of lupus, epithelioma, and other affections.