A supposed new element, a radioactive substance discovered by M. and MMe. Curie in pitchblende. It is closely related chemically to bismuth. It emits only alpha rays and is perhaps identical with radium F.
- A naturally radioactive metallic element, occurring in minute quantities as a product of radium disintegration and produced by bombarding bismuth or lead with neutrons. It has 27 isotopes ranging in mass number from 192 to 218, of which Po 210, with a half-life of 138.39 days, is the most readily available. Atomic number 84; melting point 254°C; boiling point 962°C; specific gravity 9.32; valence 2, 4. See Table at element.