a soft malleable silvery element of the lanthanide series of metals that occurs in monazite and is used to improve the mechanical properties of steel. Symbol: Yb; atomic no: 70; atomic wt: 173.04; valency: 2 or 3; relative density: 6.903 (alpha), 6.966 (beta); melting pt: 819°C; boiling pt: 1196°C
A soft, silvery-white metallic element of the lanthanide series that occurs as seven stable isotopes. It is used as a radiation source for portable x-ray machines. Atomic number 70; atomic weight 173.04; melting point 824°C; boiling point 1,196°C; specific gravity 6.972 or 6.54 (25°C) depending on allotropic form; valence 2, 3. See Periodic Table.