chemical science vs bivalent

chemical science is a noun but bivalent is not a noun.

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

chemical science (noun)	bivalent (noun)
the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions

chemical science (adjective)	bivalent (adjective)
	used of homologous chromosomes associated in pairs in synapsis
	having a valence of two or having two valences