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5 definitions found

From: DICT.TW English-Chinese Dictionary 英漢字典

 ra·di·um /ˈrediəm/

From: DICT.TW English-Chinese Medical Dictionary 英漢醫學字典

 ra·di·um /ˈredɪəm/ 名詞

From: Webster's Revised Unabridged Dictionary (1913)

 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.

From: WordNet (r) 2.0

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

From: Elements database 20001107

 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.