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 dichloride Polonium dichloride Polonium dichloride is a chemical compound of the radioactive metalloid polonium and chlorine. Its chemical formula is PoCl. Polonium dichloride appears to crystallise with an orthorhombic unit cell in either the "P"222, "P"mm2 or "Pmmm" space group, although this is likely a pseudo-cell. Alternatively, the true space group may be monoclinic or triclinic, with one or more cell angles close to 90°. Assuming the space group is "P"222, the structure exhibits distorted cubic coordination of Po as {PoCl} and distorted square planar coordination of Cl as {ClPo}. PoCl can be obtained either by halogenation of polonium metal or