arsenic group vs cacodyl

arsenic group and cacodyl both are nouns.

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

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

Other synonyms of arsenic group include cacodyl group, cacodyl radical.

arsenic group (noun)	cacodyl (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