CH 221 Section 61
March 8, 2015
In 1900, radon was the 3rd radioactive element to be found after French chemist Antoine-Henri Becquerel’s discovery of radioactivity in 1896. Originally named radium emanation then niton, for the Latin word nitens, which means shining, the International Union of Pure and Applied Chemistry (IUPAC) decided to call it radon by 1923 over other potential candidates like thoron and actinon, since it was most abundantly found from the decay of radium. Its discovery is accredited to German chemist Friedrich Ernst Dorn as he studied the decay chain of radium. In 1899, Ernest Rutherford and Robert Owens noticed that thorium released an unknown, radioactive gas during the decay process, while Marie Curie, the founder of radium and polonium, also observed the gas from radium’s decay. Rutherford’s research in 1803 determined that radon could be condensed into a liquid state and also found radon’s alpha radiation. Five years later, William Ramsay of London’s University College, who helped discover neon, krypton, and xenon, was the first to be able to study and note most of radon’s chemical and physical properties.
86 is the atomic number of radon. Radon is the densest elemental gas with a density of 9.7 g/L. In comparison, air has a density of only 1.2 g/L. It is also the only radioactive noble gas. At room temperature, radon is colorless, but it displays a yellow phosphorescence at its freezing point, (-71˚C) and becomes a reddish orange as temperature decreases. You can dissolve radon in water to form a clear liquid. Our atmosphere is 1.0E-19% radon, while nitrogen makes up 78.1% of it. An interesting characteristic of radon is that there is less than a 10˚C gap between its melting point and freezing point.
A decay product of uranium, thorium, and radium, radon poses a threat to people because it emits alpha particles that comes in direct contact with tissues when inhaled, and also decomposes into solid radioactive elements like lead, polonium, and bismuth. Industrial companies can also manufacture radon by transferring uranium ores into solutions of hydrochloric and hydrobromic acids, then condensing radon with liquid nitrogen. They can be found at hot springs like those throughout Japan, in higher concentrations, and can also accumulate in homes. The recommended safety levels for a home is to have a radon level of no greater than 4 pCi/L. A curie is equivalent to the radiation level of 1 gram of radium. In Oregon, radon levels are relatively low on the western side, and moderate on the eastern end. The exception is the area along the Columbia River in and around the Gorge, where levels are much higher. Radon gets into houses through wall cavities, cracks, and even the water supply. House testing kits are available and are somewhat affordable, and are highly recommended by the Environmental Protection Agency (EPA)1. Second only to smoking, the radiation emitted by radon is a leading cause of lung cancer deaths, amounting to between 15,000 and 22,000 deaths per year2. Ironically, radon packed in a seed, or needle, was used by doctors during radiotherapy and radiography in order to treat cancer. Eventually safer methods were developed, and now radon is not used very often. Some doctors will still administer very small dosages of radon for cancer therapy. There are several ways that people can be tested for radon in their body, most notably through levels in their urine, blood, lung, and bone tissue, though it is not commonly done, due to radon’s instability. A developing use for radon is earthquake prediction. During seismic events, uranium ore begins to break from the enormous pressure and causes it to decay into radon and other elements. Seismologists believe that the spike in radon levels in the ground could potentially be a helpful precursor to an earthquake, especially since its short half-life will allow for greater accuracy.
Due to radon’s