chemical substance vs chemical

chemical substance and chemical both are nouns.

Word	Noun	Adjective	Verb	Adverb
chemical substance	Yes	No	No	No
chemical	Yes	Yes	No	No

As nouns, chemical substance and chemical are synonyms defined as:

chemical substance and chemical: material produced by or used in a reaction involving changes in atoms or molecules

chemical substance (noun)	chemical (noun)
material produced by or used in a reaction involving changes in atoms or molecules	material produced by or used in a reaction involving changes in atoms or molecules

chemical substance (adjective)	chemical (adjective)
	relating to or used in chemistry
	of or made from or using substances produced by or used in reactions involving atomic or molecular changes