Polonium the Curies while they were investigating the cause of pitchblende radioactivity. Pitchblende, after removal of the radioactive elements uranium and thorium, was more radioactive than the uranium and thorium combined. This spurred the Curies to search for additional radioactive elements. They first separated out polonium from pitchblende in July 1898, and five months later, also isolated radium. German scientist Willy Marckwald successfully isolated 3 milligrams of polonium in 1902, though at the time he believed it was a new element, which he dubbed "radio-tellurium", and it was not until 1905 that it was demonstrated to be the same as polonium.
Polonide Polonide A polonide is a chemical compound of the radioactive element polonium with any element less electronegative than polonium. Polonides are usually prepared by a direct reaction between the elements at temperatures of around 300–400 °C. They are amongst the most chemically stable compounds of polonium, and can be divided into two broad groups: Some polonides are intermediate between these two cases and others are non-stoichiometric compounds. Alloys containing polonium are also classed as polonides. As polonium is immediately below tellurium in the periodic table, there are many chemical and structural similarities between polonides and tellurides. Lead polonide (PbPo) occurs