atomic number 20 vs fluxing lime

atomic number 20 and fluxing lime both are nouns.

Word	Noun	Adjective	Verb	Adverb
atomic number 20	Yes	No	No	No
fluxing lime	Yes	No	No	No

atomic number 20 (noun)	fluxing lime (noun)
a white metallic element that burns with a brilliant light; the fifth most abundant element in the earth's crust; an important component of most plants and animals	a white crystalline oxide used in the production of calcium hydroxide