atomic number 21

Thesaurus

Noun

1.

atomic number 21 - a white trivalent metallic element; sometimes classified in the rare earth group; occurs in the Scandinavian mineral thortveititeSc, scandiummetal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.thortveitite - a mineral consisting of scandium yttrium silicate; a source of scandium