Radon
Element 86 · Noble Gas
Radon is the heavy, radioactive member of the noble gas family, formed as uranium and radium decay in rock and soil. Being a gas, it slips through cracks in foundations and collects in basements and ground floors — the reason homes in many regions are tested for it.
Like other noble gases it barely reacts, though a few radon fluorides and oxides have been made in laboratories. Its danger is purely radiological: inhaled radon and its decay products irradiate lung tissue, making it a leading cause of lung cancer among non-smokers.
Key facts
| Atomic number | 86 |
|---|---|
| Atomic weight | [222] |
| Category | Noble Gas |
| Group / Period | 18 / 6 |
| Block | p |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 |
| Common oxidation states | 0, +2 |
| State at STP | Gas |
| Density | 9.73 g/L |
| Melting point | -71 °C |
| Boiling point | -61.70 °C |
Occurrence
Radon is continuously generated by the decay of radium in uranium- and thorium-bearing rock and soil, and seeps upward into buildings and mines.
Applications
Home radon testing and mitigation
Geological and groundwater tracing
Historic cancer therapy (radon seeds)
Common compounds
- radon difluoride
- radon trioxide
Radon is the only gas among the radioactive decay products of uranium — it can slip through concrete and collect in basements, which is why homes are tested for it.
Data source: IUPAC standard atomic weights 2021