jan 1, 1898 - 1898- Marie Curie
Marie Curie deduced that radioactivity does not depend on how atoms are arranged into molecules, but rather that it originates within the atoms themselves. She adopted her fellows ideas of radiation and did experiments until she discovered more information After Marie discovered the radioactive elements polonium and radium, Marie continued to investigate their properties. In 1910 she successfully produced radium as a pure metal, which proved the new element's existence beyond a doubt.
Added to timeline:
History of the Atom
by Katya Sander, Aurielle Smith, Amaya Mix