Radon was first detected as an emission from the radioactive decay of radium. It has an atomic number of 86 and represented with the symbol Rn in the periodic table. It is available in hot springs and some spring water. Its concentration is commonly measured in becquerel ( Bq ) per cubic meter. In the air, its concentration varies from 1 and 100 Bq per cubic meter. In some places, well water will be rich in Radon. Even rainwater can be extremely radioactive due to the high concentration of the element.
Radon gas is considered a health hazard. It is often the single largest contributor to an individual’s background radiation dose, but due to local differences in geology, the level of the radon-gas hazard differs from location to location. Despite its short lifetime, radon gas from natural sources, such as uranium-containing minerals, can accumulate in buildings, especially, due to its high density, in low areas such as basements and crawl spaces.
Characteristics of Radon
- It is colorless, tasteless, odorless gas at standard pressure and temperature and it is the densest noble gas.
- It is highly radioactive and chemically unreactive.
- At standard temperature and pressure, It forms a monatomic gas with a density of 9.73 kg/m3, about 8 times the density of the Earth’s atmosphere at sea level, 1.217 kg/m3.
- It is one of the densest gases at room temperature and is the densest of the noble gases. Although colorless at standard temperature and pressure, when cooled below its freezing point of 202 K (−71 °C; −96 °F), radon emits a brilliant radioluminescence that turns from yellow to orange-red as the temperature lowers.