open-chain vs chemistry

open-chain is not a noun while chemistry is a noun.

Word	Noun	Adjective	Verb	Adverb
open-chain	No	Yes	No	No
chemistry	Yes	No	No	No

open-chain (noun)	chemistry (noun)
	the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions
	the way two individuals relate to each other
	the chemical composition and properties of a substance or object

open-chain (adjective)	chemistry (adjective)
having an open chain structure