exradio

1 definition found

exradio - Collaborative International Dictionary of English v.0.48 :

  Radon \Ra"don\ (r[=a]"d[o^]n), n. (Chem.)
     An intensely radioactive gaseous element produced by the
     radioactive decay of radium-226, which is the main isotope of
     radium found in pitchblende. Chemically it is an inert noble
     gas. Its atomic symbol is Rn. It has an atomic number of 86.
     The radon isotope produced by decay of radium has an atomic
     weight of 222.017, and this isotope decays by alpha emission
     with a half-life of 3.82 days. Numerous other isotopes have
     been observed, all radioactive and all having half-lives
     shorter than that of radon-222. Radon was discovered by M.
     and Mme. Curie, of Paris, in their studies of the radioactive
     substances in pitchblende. Radon was originally called
     radium emanation or exradio.
     [PJC]