1898-1902 – France
‘Pitchblende, the ore from which uranium is extracted, is much more radioactive than pure uranium. The ore must therefore contain unknown radioactive elements’
Following the discovery of radioactivity by HENRI BECQUEREL (1852-1908) in 1896, Marie Curie conclusively proved that radioactivity is an intrinsic property of the element in question and is not a condition caused by outside factors.
She correctly concluded that pitchblende contained other, more radioactive elements than uranium.
The Curies isolated two new radioactive elements, polonium and radium, from pitchblende. The discovery of new elements by their radioactivity was proof that radioactivity was a property of atoms.
Even today, Marie Curie’s notebooks of her studies remain too radioactive to handle.