Welcome to Tantalum on 66th St. Tantalum is a chemical element with the symbol Ta and Atomic number of 73. Previously known as tantalum, its name comes from Tantalus, a character from Greek mythology. Tantalum is a rare, blue-gray, lustrous transition metal that is highly corrosion-resistant. It is part of the refractory metals group, which are widely used in minor components as alloys. The chemical inertness of tantalum makes it a valuable substance for laboratory equipment.