a hard, gray, ductile, corrosion-resistant, metallic chemical element found in various minerals and used in making nuclear reactors, chemical equipment, missiles, electronic components, etc.: symbol, Ta; at. no., 73
See tantalum in American Heritage Dictionary 4
(tănˈtə-ləm)
noun Symbol Ta
A very hard, heavy, gray metallic element that is exceptionally resistant to chemical attack below 150°C. It is used to make light-bulb filaments, electrolytic capacitors, lightning arresters, nuclear reactor parts, and some surgical instruments. Atomic number 73; atomic weight 180.948; melting point 2,996°C; boiling point 5,425°C; specific gravity 16.6; valence 2, 3, 4, 5. See Table at element.