Radium-226 () is the most stable and common isotope of Radium. It has a half-life of approximately 1,600 years and is a key member of the Uranium Decay Series (the decay chain of Uranium-238).
Radium-226 decays into Radon-222 () via the emission of an alpha particle. This decay is part of a larger chain that eventually ends in stable Lead-206.
The decay equation is:
Because Radium-226 is a decay product of Uranium-238, it is found in almost all rocks and soils. It is a significant concern in mining operations, where it can accumulate in tailings and leach into groundwater.
One of the most significant characteristics of Radium-226 is that its primary decay product, Radon-222, is a noble gas. This allows the radioactivity to "escape" from solid minerals and accumulate in enclosed spaces, posing an inhalation hazard.