Radium was discovered by Marie Sklodowska Curie, a Polish chemist, and Pierre Curie, a French chemist, in 1898. Marie Curie obtained radium from pitchblende, a material that contains uranium, after noticing that unrefined pitchblende was more radioactive than the uranium that was separated from it. She reasoned that pitchblende must contain at least one other radioactive element. Curie needed to refine several tons of pitchblende in order to obtain tiny amounts of radium and polonium, another radioactive element discovered by Curie. One ton of uranium ore contains only about 0.14 grams of radium. Today, radium can be obtained as a byproduct of refining uranium and is usually sold as radium chloride (RaCl₂) or radium bromide (RaBr₂) and not as a pure material.

Uses

Radium had been used to make self-luminous paints for watches, aircraft instrument dials and other instrumentation, but has largely been replaced by cobalt-60, a less dangerous radioactive source. A mixture of radium and beryllium will emit neutrons and is used as a neutron source. Radium paint was used in the mid 1900s to paint the hands and numbers of some clocks and watches. The paint was composed of radium salts and a phosphor and glowed in the dark. Radium emits a, b, and g rays and when mixed with beryllium produces neutrons. Inhalation, injection, or body exposure to radium can cause cancer and other body disorders.