atomic theory vs chemical science

atomic theory and chemical science both are nouns.

Word	Noun	Adjective	Verb	Adverb
atomic theory	Yes	No	No	No
chemical science	Yes	No	No	No

atomic theory (noun)	chemical science (noun)
(chemistry) any theory in which all matter is composed of tiny discrete finite indivisible indestructible particles	the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions
a theory of the structure of the atom