cacodyl vs arsenic group

cacodyl and arsenic group both are nouns.

Word	Noun	Adjective	Verb	Adverb
cacodyl	Yes	No	No	No
arsenic group	Yes	No	No	No

As nouns, cacodyl and arsenic group are synonyms defined as:

Other synonyms of cacodyl include cacodyl group, cacodyl radical.

cacodyl (noun)	arsenic group (noun)
the univalent group derived from arsine	the univalent group derived from arsine
a poisonous oily liquid with a garlicky odor composed of 2 cacodyl groups; undergoes spontaneous combustion in dry air