Radon
Radioactive noble gas; second leading cause of lung cancer.
Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive noble gas, colorless and odorless, and is one of the rarest elements due to the instability of its most stable isotope, 222Rn. Radon is significant as a natural radioactive contaminant that affects indoor air quality worldwide and is the second most frequent cause of lung cancer after cigarette smoking.
- symbol
- Rn
- atomic_number
- 86
- discoverers
- Ernest Rutherford and Robert B. Owens
- density
- 9.73 kg/m³ at STP
Lore & Background
Owens at McGill University in Montreal, and was the fifth radioactive element to be discovered. Initially known as 'emanation', the radioactive gas was identified during experiments with radium, thorium oxide, and actinium by Friedrich Ernst Dorn, Rutherford and Owens, and André-Louis Debierne, respectively. Each element's emanation was considered a separate substance: radon, thoron, and actinon.
Reader's Guide
Radon is a naturally occurring radioactive gas that arises from the decay of uranium and thorium in the ground. Radon is denser than air and accumulates in basements and crawlspaces, posing a health risk. Epidemiological studies have shown a clear association between breathing high concentrations of radon and incidence of lung cancer. It is the second most frequent cause of lung cancer after smoking, and the number one cause among non-smokers. Radon can be tested for in buildings and mitigated using techniques such as sub-slab depressurization. Its chemical reactivity is low, but it can form compounds such as radon difluoride (RnF2) and radon trioxide (RnO3).
Did You Know?
- Radon is the densest of the noble gases, with a density about 8 times that of Earth's atmosphere at sea level.
- Radon trapped in permafrost may be released by climate-change-induced thawing.
- The decay of radon produces many short-lived nuclides called 'radon daughters', ending at stable isotopes of lead.
Frequently Asked Questions
Who is Radon?
Radon is a colorless, odorless noble gas with atomic number 86 and symbol Rn, sitting at the tail end of the periodic table's noble-gas column. It is a naturally occurring radioactive element that no human sense can detect, making it a truly invisible member of the element roster.
What are Radon's powers or role in the element world?
Radon's defining trait is its radioactivity: its most stable isotope, Rn-222, decays with a half-life of roughly 3.8 days while emitting alpha particles. In practical terms, its role is as a natural indoor-air contaminant that seeps up through soil and bedrock into homes and workplaces.
How was Radon discovered?
In 1900, Ernest Rutherford and Robert B. Owens noticed a mysterious gaseous by-product being released from radium compounds and initially dubbed it 'radium emanation.' The substance was later recognized as a distinct element, given the name Radon, and assigned its own square on the periodic table.
Why is Radon so rare on Earth?
Every isotope of Radon is radioactive and decays within days to weeks, so no stable form ever accumulates in the crust. The most persistent isotope, Rn-222, lasts only about 3.8 days before transforming into polonium, meaning Radon exists in a constant, tiny cycle of creation and destruction.
Why is Radon a major health concern?
Radon is the second leading cause of lung cancer after cigarette smoking, because its short-lived decay products lodge in lung tissue and deliver concentrated alpha-radiation doses. Since the gas is invisible and odorless, people can inhale it for years without realizing, which is why indoor radon testing is widely recommended.
More in Chemical Elements & Metals 1-20
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