Atomic weight of an element expressed in grams is called its gram atomic weight or gram atom or mole atom.
(i) No. of gram atoms or mole atoms = \(\frac{\text{Wt. of an element }}{\text{GAW}}\)
(ii) Wt. of an element in g = No. of g atom × GAW
(iii) No. of atoms in 1GAW = 6.02 x 1023
No. of atoms in given substance = No. of GAW x 6.02 x 1023
\(= \frac{\text{Weight }}{\text{GAW}} \times 6.02 \times 10^{23}\)
e.g., No. of atoms in 5.4 g of Ag = \(\frac{5.4}{108} \times 6.02 \times 10^{23}\)
\( = 3.01 \times 10^{23}\)
(iv) No. of atoms in 1 g of an element = \(\frac{6.02 \times 10^{23}}{\text{At. Wt.}}\)
(v) Wt. of one atom of the element (in g) = \(\frac{\text{GAW}}{6.02 \times 10^{23}}\)
e.g., Wt. of 1 atom of S = \(\frac{32}{6.02 \times 10^{23}}\)
\(= 5.33 \times 10^{-23}g\)
