Polonium

Polonium (IPA: /pə(ʊ)ˈləʊniəm/) is a chemical element in the periodic table that has the symbol Po and atomic number 84. A rare and highly radioactive metalloid, polonium is chemically similar to tellurium and bismuth, and it occurs in uranium ores. Polonium has been studied for possible use in heating spacecraft. It is unstable; all isotopes of polonium are radioactive.