Radon-222
Radon-222 (222Rn, Rn-222, historically radium emanation or radon) is the most stable isotope of radon, with a half-life of approximately 3.8 days. It is transient in the decay chain of primordial uranium-238 and is the immediate decay product of radium-226. Radon-222 was first observed in 1899, and was identified as an isotope of a new element several years later. In 1957, the name radon, formerly the name of only radon-222, became the name of the element. Owing to its gaseous nature and high radioactivity, radon-222 is one of the leading causes of lung cancer.
| General | |
|---|---|
| Symbol | 222Rn |
| Names | radon-222, 222Rn, Rn-222, Radium emanation |
| Protons (Z) | 86 |
| Neutrons (N) | 136 |
| Nuclide data | |
| Natural abundance | Trace |
| Half-life (t1/2) | 3.8215 d |
| Isotope mass | 222.0175763 Da |
| Spin | 0 |
| Parent isotopes | 226Ra (α) |
| Decay products | 218Po |
| Decay modes | |
| Decay mode | Decay energy (MeV) |
| Alpha decay | 5.5904 |
| Isotopes of radon Complete table of nuclides | |
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