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[1] |
Isotope mass | 222.0175763[2] Da |
Spin | 0 |
Parent isotopes | 226Ra (α) |
Decay products | 218Po |
Decay modes | |
Decay mode | Decay energy (MeV) |
Alpha decay | 5.5904[2] |
Isotopes of radon Complete table of nuclides |
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.[3]
EPA02
was invoked but never defined (see the help page).