Marie Curie won the 1911 Nobel Prize in Chemistry for discoveries involving radium and polonium.
The award recognized her discovery of the elements polonium and radium, her study of their properties, and her successful isolation of radium. She had earlier shared the 1903 Nobel Prize in Physics for work on radioactivity, making her the first person to receive two Nobel Prizes.
Curie and Pierre Curie discovered polonium and radium in 1898 while examining pitchblende, a uranium ore. The name polonium referred to Marie Curie’s homeland, Poland. Isolating radium required processing large quantities of ore and carefully separating its compounds.
A common mix-up is confusing Curie’s 1911 Chemistry award with her 1903 Physics award. The later prize was specifically about radioactive elements and their chemistry, not simply the general discovery of radioactivity.