Radon
Definition and meaning of Radon in chemistry.
![Radon element card: symbol Rn, atomic number 86, atomic mass [222], electron configuration [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶, Noble gas, group 18, period 6, gas at room temperature.](/assets/images/terms/radon-chemical-element.webp)
Radon is a colorless, odorless, and highly radioactive noble gas. Its chemical symbol is Rn, and it has an atomic number of 86. It is the heaviest naturally occurring noble gas on the periodic table. Radon poses a significant, hidden health hazard when it accumulates inside poorly ventilated enclosed spaces.
In more detail
Radon resides in group 18 of the periodic table of elements. It is continuously formed by the natural radioactive decay of the element radium. Radium itself is a decay product of uranium and thorium naturally found in global soils and rocks.
Being a noble gas, radon is remarkably chemically inert under standard environmental conditions. This means it almost never reacts with other elements in nature. However, it can form a few simple chemical compounds under extreme laboratory conditions.
For example, scientists have successfully forced it to react and form radon difluoride (RnF2). Radon gas easily diffuses out of the ground and escapes upward into the atmosphere. It can accumulate and concentrate heavily in building basements, underground mines, and poorly sealed houses.
The most stable natural isotope is radon-222, which possesses a half-life of about 3.8 days. This radioactive isotope predictably decays into heavy, solid radioactive elements that can be deeply inhaled. Prolonged exposure to concentrated radon and its radioactive decay products is extremely dangerous. Medical experts widely recognize this exposure as a leading global cause of severe lung cancer.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Rn |
| Atomic number | 86 |
| Atomic mass | [222] u |
| Category | Noble-Gas |
| State at room temperature | Gas |
| Year discovered | 1899 |
Radon gas naturally seeps continuously from uranium-bearing soil and the underlying bedrock. It often rises directly into household basements through tiny, invisible cracks in the concrete foundation. Because it is heavier than air, the gas tends to settle and pool in these lower levels. This necessitates the widespread use of active mitigation ventilation systems in severely affected residential homes. These special systems use fans to safely vent the dangerous radioactive gas outside into the open atmosphere.
Frequently asked questions
Why is radon gas dangerous if it is chemically inert?
The danger of radon completely originates from its radioactivity rather than its chemical reactivity. It decays into heavy, solid radioactive particles that can permanently lodge in the lungs. Once inside, these particles emit DNA-damaging alpha particles that can cause cancer.
How can a homeowner detect radon inside a building?
Radon gas is entirely invisible and completely odorless to human senses. It can only be accurately detected using specialized short-term or long-term radon test kits. These test kits sensitively measure the local radiation levels in the basement or home.
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Sources & references
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