atomic number 63


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Noun1.atomic number 63 - a bivalent and trivalent metallic element of the rare earth groupatomic number 63 - a bivalent and trivalent metallic element of the rare earth group
metal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.
monazite - a reddish-brown mineral containing rare earth metals; an important source of thorium and cerium