Radium components: compounds of barium, which gave a brilliant green flame color, and unknown radioactive compounds which gave carmine spectral lines that had never been documented before. The Curies found the radioactive compounds to be very similar to the barium compounds, except that they were more insoluble. This made it possible for the Curies to separate out the radioactive compounds and discover a new element in them. The Curies announced their discovery to the French Academy of Sciences on 26 December 1898. The naming of radium dates to about 1899, from the French word "radium", formed in Modern Latin from "radius"
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