Given the atomic weight of a substance, we can calculate the mass of a given number of atoms by converting them to moles. We know that one mole of a substance contains an Avogadro's number of atoms or 6.023 x 10^23 atoms.
that is, 6.023 x 10^23 atoms constitute one mole of a substance. Here we have 3.17 x 10^20 atoms.
Number of moles of the element = `(3.17 xx 10^20)/ (6.023 xx 10^23) = 5.26 xx 10^(-4)`
The atomic weight of the element = x gm/mole
Thus the mass of the given number of atoms can be calculated by multiplying the number of moles by atomic weight as:
Mass of atoms = 5.26 x 10^-4 x gm.
Thus, we can use the mole concept to determine the mass of a given number of atoms of an element with a known atomic weight.
Hope this helps.