History of chemistry element among the fractions that resulted. Working with the mineral pitchblende, the pair discovered a new radioactive element in 1898. They named the element polonium, after Marie's native country of Poland. On December 21, 1898, the Curies detected the presence of another radioactive material in the pitchblende. They presented this finding to the French Academy of Sciences on December 26, proposing that the new element be called radium. The Curies then went to work isolating polonium and radium from naturally occurring compounds to prove that they were new elements. In 1902, the Curies announced that they had produced a decigram
Polonium dioxide the scarcity of polonium in nature and the high temperatures (250 °C) required to form the dioxide. Polonium dioxide is prepared by reacting elemental polonium with oxygen at 250 °C or by thermal decomposition of polonium(IV) hydroxide (PoO(OH)), polonium disulfate (Po(SO)), polonium selenate (Po(SeO)), or polonium tetranitrate (Po(NO)). When placed in hydrogen, polonium dioxide is slowly reduced to metallic polonium at 200 °C; the same reduction occurs at 250 °C in ammonia or hydrogen sulfide. When heated in sulfur dioxide at 250 °C, a white compound is formed, possibly a polonium sulfite. When polonium dioxide is hydrated, polonous acid (HPoO),