as they remain radioactive. Radium occurs naturally as uranium decays - though only in very small quantities. It took many tonnes of pitchblende to produce the tenth of a gram of radium that the ...

naturally formed - albeit briefly - during radioactive decay of other elements, the amount of francium on earth is tiny. It has been estimated that at any one time there is less than a kilogram of the ...

Stable isotopes are non-radioactive forms of atoms. Although they do not emit radiation, their unique properties enable them to be used in a broad variety of applications, including water and soil ...