Radon (Rn)
Radon: The Invisible, Radioactive Gas
Radon is a colorless, odorless noble gas that is highly radioactive. It forms naturally when radium in rocks and soil decays. Though invisible, radon can pose serious health risks when it builds up indoors.
Why Is Radon Useful?
Radon’s extreme radioactivity limits its uses, but it has had some niche applications:
Cancer Therapy (Historical): In the past, doctors used radon in a treatment called brachytherapy, where sealed tubes of the gas were implanted into tumors. This method is rare today because safer treatments exist.
Environmental Health: Radon can collect in basements and buildings, especially in areas with granite-rich soil. Testing kits help homeowners detect dangerous concentrations so they can take steps to reduce them.
Geological Research: Scientists use radon to study air circulation in the atmosphere and to help track geological faults.
Biological Role & Natural Abundance
Radon has no biological role. In fact, it is a carcinogen—after smoking, radon exposure is the second leading cause of lung cancer. It also contributes to background radiation on Earth and may have played a role in evolution by causing genetic mutations.
Radon is continuously produced as radium-226 decays, seeping out of rocks, soil, and groundwater. While rare in the atmosphere, it is measurable and detectable.
History of Discovery
1899: Ernest Rutherford and Robert B. Owens noticed a radioactive gas released from thorium. Around the same time, Marie and Pierre Curie detected a similar gas from radium.
1900: Friedrich Ernst Dorn reported that a gas collected inside radium ampoules.
1908: William Ramsay and Robert Whytlaw-Gray managed to collect enough radon to study its properties. They found it was the heaviest known gas and confirmed it was a new element, naming it radium emanation—later renamed radon.