break down vs chemical science

break down is not a noun while chemical science is a noun.

Word	Noun	Adjective	Verb	Adverb
break down	No	No	Yes	No
chemical science	Yes	No	No	No

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

break down (verb)	chemical science (verb)
collapse due to fatigue, an illness, or a sudden attack
stop operating or functioning
separate (substances) into constituent elements or parts
make a mathematical, chemical, or grammatical analysis of; break down into components or essential features
make ineffective
cause to fall or collapse
lose control of one's emotions
fall apart