chemical science vs chemical compound

chemical science and chemical compound both are nouns.

Word	Noun	Adjective	Verb	Adverb
chemical science	Yes	No	No	No
chemical compound	Yes	No	No	No

chemical science (noun)	chemical compound (noun)
the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions	(chemistry) a substance formed by chemical union of two or more elements or ingredients in definite proportion by weight