What does "atomic number 39" mean?

a silvery metallic element that is common in rare-earth minerals; used in magnesium and aluminum alloys

What is a synonym for "atomic number 39"?

Common synonyms include: y, yttrium.

Rare ·Advanced level

Noun

1
a silvery metallic element that is common in rare-earth minerals; used in magnesium and aluminum alloys wordnet