gram-atomic weight vs gram atom

gram-atomic weight and gram atom both are nouns.

Word	Noun	Adjective	Verb	Adverb
gram-atomic weight	Yes	No	No	No
gram atom	Yes	No	No	No

As nouns, gram-atomic weight and gram atom are synonyms defined as:

gram-atomic weight and gram atom: the quantity of an element whose weight in grams is numerically equal to the atomic weight of the element

gram-atomic weight (noun)	gram atom (noun)
the quantity of an element whose weight in grams is numerically equal to the atomic weight of the element	the quantity of an element whose weight in grams is numerically equal to the atomic weight of the element