n. Symbol Lu A silvery-white element of the lanthanide series that is exceptionally difficult to separate from the other rare-earth elements with which it is found, used in nuclear technology. Atomic number 71; atomic weight 174.97; melting point 1,663°C; boiling point 3,402°C; specific gravity 9.841 (at 25°C); valence 3. See Periodic Table. [Latin Lutetia, ancient name of Paris, France (where it was discovered) + -IUM.] |
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