atomic number 18 vs argonon

atomic number 18 and argonon both are nouns.

Word	Noun	Adjective	Verb	Adverb
atomic number 18	Yes	No	No	No
argonon	Yes	No	No	No

As nouns, argonon is a hypernym of atomic number 18; that is, argonon is a word with a broader meaning than atomic number 18:

atomic number 18: a colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere
argonon: any of the chemically inert gaseous elements of the helium group in the periodic table

Other hypernyms of atomic number 18 include inert gas, noble gas.

atomic number 18 (noun)	argonon (noun)
a colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere	any of the chemically inert gaseous elements of the helium group in the periodic table