Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
the number of grams of a chemical element equal to its atomic weight. Thus, for example, for hydrogen (atomic weight 1.00797) the gram atom is 1.00797 g and for uranium (atomic weight 238.03), 238.03 g. The number of atoms in one gram atom of any element is equal to Avoga-dro’s number, that is, 6.02252 x 1023. The gram atom quantity enters into the most diverse calculations in physics and chemistry. In technical computations the kilogram atom and ton atom are often used (I kilogram-atom of hydrogen equals 1.00797 kg).