Discovery of Polonium and Radium

Marie and Pierre Curie announced the discovery of a new radioactive element in July 1898, which they named polonium after Marie's native Poland, and a second, more strongly radioactive element in December 1898, which they named radium for its radioactivity. Both were extracted from pitchblende, a uranium ore, by fractional crystallization carried out at industrial scale in a converted shed at the School of Physics in Paris; isolating a pure sample of radium chloride took until 1902 and required processing several tons of ore for roughly one-tenth of a gram of the pure salt. The work rested on Henri Becquerel's 1896 observation that uranium compounds emitted a penetrating radiation on their own, which Marie Curie's doctoral research showed was an atomic property rather than a chemical reaction, a finding she and Pierre Curie extended by tracking that same radiation to find new elements hidden in the ore in far smaller quantities than uranium itself. Marie Curie's 1911 Nobel Prize in Chemistry, her second Nobel Prize, was awarded specifically for the discovery of polonium and radium and for isolating radium in its pure metallic form.