Marie Curie was present in such minute quantities that they would eventually have to process tons of the ore. In July 1898, Curie and her husband published a joint paper announcing the existence of an element which 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". To prove their discoveries beyond any
Polonium a volatile liquid at room temperature prone to dissociation; it is thermally unstable. Water is the only other known hydrogen chalcogenide which is a liquid at room temperature; however, this is due to hydrogen bonding. The two oxides PoO and PoO are the products of oxidation of polonium. Halides of the structure PoX, PoX and PoF are known. They are soluble in the corresponding hydrogen halides, i.e., PoCl in HCl, PoBr in HBr and PoI in HI. Polonium dihalides are formed by direct reaction of the elements or by reduction of PoCl with SO and with PoBr with HS at