total potassium

Is Potassium 40 Radioactive? Potassium-40 (40K) is a naturally occurring radioactive isotope Why would you expect potassium-40 to be radioactive? When an atom of potassium 40 decays into argon 40, the argon atom produced is trapped by the crystalline structure of the lava. … Along with uranium and thorium, potassium contributes to the natural radioactivity