My first result was the finding that the activity of the uranium compounds depended only on the quantity of uranium present. I hypothesized that the radiation was not the outcome of some interaction of molecules but must come from the atom itself. This hypothesis was an important step in disproving the assumption that atoms were indivisible.
In July 1898, Curie and her husband published a joint paper announcing the existence of an element they named “polonium”, in honour of her native Poland, which would for another twenty years remain partitioned among three empires (Russian, Austrian, and Prussian). On 26 December 1898, the Curies announced the existence of a second element, which they named “radium”, from the Latin word for “ray”. In the course of their research, they also coined the word “radioactivity”.
J. Phys. Radium (1920)
The curie (symbol Ci) is a non-SI unit of radioactivity originally defined in 1910. According to a notice in Nature at the time, it was named in honour of Pierre Curie, but was considered at least by some to be in honour of Marie Curie as well.
