Quick Facts
| Property | Value |
|---|---|
| Symbol | Rn |
| Atomic Number | 86 |
| Atomic Mass | [222] u |
| Category | Noble Gas |
| Period | 6 |
| Group | 18 |
| Block | p |
| Electron Configuration | [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶ |
Physical Properties
| Property | Value |
|---|---|
| State at 20°C | Gas |
| Density | 0.00973 g/cm³ |
| Melting Point | -71°C (202 K) |
| Boiling Point | -61.7°C (211.45 K) |
| Appearance | Colorless gas (glows in high concentrations) |
History and Discovery
Discovered by: Friedrich Ernst Dorn Year of Discovery: 1900 Location: Halle, Germany
Etymology
From "radium" + "-on" (noble gas suffix), as it is produced by radium decay.
Occurrence
Radon is produced continuously from the decay of uranium and radium in rocks and soil. It seeps into buildings and can accumulate to dangerous levels.
Health Hazards
- Second leading cause of lung cancer after smoking
- Home radon testing is recommended
- Radon mitigation systems can reduce indoor levels
- Colorless and odorless, so testing is essential
Interesting Facts
- Second leading cause of lung cancer (after smoking)
- Naturally occurs in many homes from soil decay
- Densest gas under standard conditions
- Was once used in "radon spas" for supposed health benefits
- EPA recommends testing all homes for radon