Radium is a radionuclide (atom with excess nuclear energy, making it unstable). It is naturally occurring in the Earth’s crust as well as uranium ore. After a long period of radioactive decay, radium will eventually turn into lead. Radionuclides are known to cause an increased risk of cancer, anemia, and cataracts. Erosion of natural deposits cause radium to seep into the water supply.

Radium is a naturally radioactive, silvery-white metal when freshly cut. It blackens on exposure to air. Purified radium and some radium compounds glow in the dark (luminesce). The radiation emitted by radium can also cause certain materials, called “phosphors” to emit light. Mixtures of radium salts and appropriate phosphors were widely used for clock dials and gauges before the risks of radium exposure were understood. Metallic radium is highly chemically reactive. It forms compounds that are very similar to barium compounds, making separation of the two elements difficult. The various isotopes of radium originate from the radioactive decay of uranium or thorium. Radium-226 is found in the uranium-238 decay series, and radium-228 and -224 are found in the thorium-232 decay series. Radium-226, the most common isotope, is an alpha emitter, with accompanying gamma radiation, and has a half-life of about 1600 years. Radium-228, is principally a beta emitter and has a half-life of 5.76 years. Radium-224, an alpha emitter, has a half life of 3.66 days. Radium decays to form isotopes of the radioactive gas radon, which is not chemically reactive. Stable lead is the final product of this lengthy radioactive decay series.

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