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Alkaline Earth Metals


Radium (Ra) is atomic number 88, has an atomic weight of 226 amu, and has melting and boiling points of about 1,292°F (700°C) and about 2,084°F (1,140°C), respectively. It was discovered by Marie and Pierre Curie in 1898; they extracted a small quantity as radium chloride by processing tons of the uranium ore called pitchblende. Radium exists in the earth's crust in only about 0.6 parts per trillion, and almost none can be found in seawater. All of the isotopes of radium are radioactive, and consequently hazardous to living things. It was formerly used in medicine to treat various kinds of cancer and other conditions, but its use has declined as safer radioisotopes have been discovered. Radium was also used to paint the luminous numbers on watch dials, but that use has been stopped for safety reasons.



Emsley, John. Nature's Building Blocks: An A-Z Guide to the Elements. Oxford: Oxford University Press, 2002.

Greenwood, N. N. and A. Earnshaw. Chemistry of the Elements. New York: Butterworth-Heinemann, 1997.

Gail B. C. Marsella

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Science EncyclopediaScience & Philosophy: Adrenoceptor (adrenoreceptor; adrenergic receptor) to AmbientAlkaline Earth Metals - Beryllium, Magnesium, Calcium, Strontium, Barium, Radium