Polonium

A radioactive chemical element discovered by M and MMe Curie in pitchblende and originally called radium F It has atomic number 84 and an atomic weight of 210 It is a very rare natural element having an abundance in uranium ores only 02 that of radium It is closely related chemically to bismuth It emits only alpha rays and has a half life of 138 days It is thus more unstable than radium and a milligram of polonium emits as many alpha particles as 5 grams of radium Twenty seven isotopes are known with atomic masses from 192 to 218 At present a more practical method of preparation than isolation from ores is the preparation by neutron bombardment of bismuth in a nuclear reactor and it may be obtained commercially by users having an appropriate permit