from The Century Dictionary.
- noun In chem., a quantity of an element whose weight in grams is numerically equal to the atomic weight of the element.
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Following the discovery of the fundamental laws of chemistry, units called, for example, "gram-atom" and "gram-molecule," were used to specify amounts of chemical elements or compounds.
For each simple substance the gram-molecule of a compound contains as many gram-atoms as the molecule contains atoms of this simple substance, and the gram-atom is the product of the mass of the atom and Avogadro's number N.