Radium seventh of a gram of radium. One kilogram of the Earth's crust contains about 900 picograms of radium, and one liter of sea water contains about 89 femtograms of radium. Radium was discovered by Marie Sklodowska-Curie and her husband Pierre Curie on 21 December 1898, in a uraninite (pitchblende) sample. While studying the mineral earlier, the Curies removed uranium from it and found that the remaining material was still radioactive. They separated out an element similar to bismuth from pitchblende in July 1898, that turned out to be polonium. They then separated out a radioactive mixture consisting mostly of two
Polonium hydride metal and nascent hydrogen may produce polonium hydride. Polonium hydride is a more covalent compound than most metal hydrides because polonium straddles the border between metals and metalloids and has some nonmetallic properties. It is intermediate between a hydrogen halide like hydrogen chloride and a metal hydride like stannane. It should have properties similar to that of hydrogen selenide and hydrogen telluride, other borderline hydrides. It is very unstable at room temperature and must be stored at freezer temperatures to prevent reversion to elemental polonium and hydrogen; this is because it is an endothermic compound, like the lighter hydrogen telluride