What does "atomic number 21" mean?

a white trivalent metallic element; sometimes classified in the rare earth group; occurs in the Scandinavian mineral thortveitite

What is a synonym for "atomic number 21"?

Common synonyms include: sc, scandium.

Rare ·Advanced level

Noun

1
a white trivalent metallic element; sometimes classified in the rare earth group; occurs in the Scandinavian mineral thortveitite wordnet