Of all the elements, radium has possibly swung the farthest from good to bad in the public consciousness. Radium was discovered by the famous husband/wife team of Pierre & Marie Curie. By 1898, the mineral pitchblende (right) was known to be an ore of radioactive uranium and thorium. Marie's careful measurements showed that the known elements could not account for all of the mineral's radioactivity. This led her to discover element 84, polonium. Five months later, the couple had processed large amounts of pitchblende to isolate a salt containing yet another new element. (A major clue: the salt glowed in the dark.) This second new element was named radium.
More than a decade after these discoveries, Marie Curie and chemist André-Louis Debierne used electrolysis to produce the bare metal radium. After World War One, commercial production of radium was underway. Glowing radium paint was added to watch dials, clock faces, and instrument panels in the 1920s (right). Also in that decade, "radium water" was sold as a patent medicine (below). This was just what it sounds like, water irradiated by uranium or radium. Indeed, various cosmetics and edibles were marketed as containing healthful radium.
But, even as radium was distributed commercially, scientists in the 1920s knew of the dangers of radiation. The public soon became aware as well. The "Radium Girls" were watch-dial painters who contracted cancer from the habit of licking their paintbrushes. Their lawsuit against their employer was widely publicized. Also, Marie Curie herself died from radiation exposure, in 1933 at age 66.
A genuinely helpful application of radium was in the treatment of cancer. As a follow-up to studies begun by Curie, cancer sanitariums in Toronto, London, and elsewhere used radiation from radium to treat cancer tumors. Later, these institutions would make the safer choice of using radon gas extracted from radium.
Mining and Production
Radium is a radioactive, unstable element, continually being produced from the decay of uranium and thorium and itself continually decaying. A ton of pitchblende ore contains much less than a gram of radium. Thus, the amount of radium on Earth at any given moment is relatively small and diffuse. The annual production of radium is perhaps 100 grams, derived mainly from reprocessing spent uranium fuel rods.
Properties and Uses
Chemical investigations of radium have been somewhat limited. Its behavior resembles that of barium, the element above it in the periodic table. Radium is a silvery metal that oxidizes to black on exposure to air. It is reactive with most of the elements on the right side of the periodic table, with which it forms various salts and earths.
Radium is significantly radioactive, as are all of its compounds. The radiation excites air molecules, which can be seen to glow in the dark. Much of this radiation can be blocked with thin shielding or a few inches of air. Yet, some radium decays into the radioactive gas radon. Radon is dangerous not only for its strong radioactivity, but for its ability to leak through barriers. Radon is much heavier than air and will occasionally be found seeping into basements from natural radiation in the soil. It can be inhaled into the lungs.
Radium has few modern uses. It will occasionally be used to treat cancer. It is also a radiation source for industrial applications, but other choices are cheaper or less dangerous.