ra·di·um /ˈrediəm/
 鐳


 ra·di·um /ˈredɪəm/ 名詞
 鐳


 Ra·di·um n.  Chem. An intensely radioactive metallic element found (combined) in minute quantities in pitchblende, and various other uranium minerals. Symbol, Ra; atomic weight, 226.4.  Radium was discovered by M. and Mme. Curie, of Paris, who in 1902 separated compounds of it by a tedious process from pitchblende.  Its compounds color flames carmine and give a characteristic spectrum.  It is divalent, resembling barium chemically.  The main isotope of radium found in pitchblende, radium-226, has a half-life of 1620 years, decaying first by alpha emission to radon.
 =
 See also mesothorium.

 ◄ ►


 radium
      n : an intensely radioactive metallic element that occurs in
          minute amounts in uranium ores [syn: Ra, {atomic number
          88]


 radium
 Symbol: Ra
 Atomic number: 88
 Atomic weight: (226)
 Radioactive metallic transuranic element, belongs to group 2 of the
 periodic table. Most stable isotope, Ra-226 has a half-life of 1602 years,
 which decays into radon. Isolated from pitchblende in 1898 Marie and
 Pierre Curie.