atomic number 68 vs Er

atomic number 68 and Er both are nouns.

Word	Noun	Adjective	Verb	Adverb
atomic number 68	Yes	No	No	No
Er	Yes	No	No	No

As nouns, atomic number 68 and Er are synonyms defined as:

atomic number 68 and Er: a trivalent metallic element of the rare earth group; occurs with yttrium

Other synonyms of atomic number 68 include erbium.

atomic number 68 (noun)	Er (noun)
a trivalent metallic element of the rare earth group; occurs with yttrium	a trivalent metallic element of the rare earth group; occurs with yttrium