So, step one is to convert molecules to moles by dividing by Avogadro's number (6.022*10^23). Second step, once you have a number of moles, is to multiply it by the molar mass of the compound. You can find this by adding the molar mass of each atom in the formula.
Similarly, you may ask, how many grams is an atom?
It is equal to Avogadro's number (NA), namely 6.022 x1023. If we have one mole of water, then we know that it will have a mass of 2 grams (for 2 moles of H atoms) + 16 grams (for one mole O atom) = 18 grams.
How do you calculate the number of atoms?
Avogadro's number is a very important relationship to remember: 1 mole = 6.022×1023 6.022 × 10 23 atoms, molecules, protons, etc. To convert from moles to atoms, multiply the molar amount by Avogadro's number. To convert from atoms to moles, divide the atom amount by Avogadro's number (or multiply by its reciprocal).
How do you determine how many atoms are in a sample?
Multiply the number of moles in your sample by the atoms per mole, Avogadro's number. The result is the final answer -- the number of atoms in your sample. In the example you calculated .222 moles. Multiply .222 moles by 6.022 x 10^23 atoms per mole to arrive at the answer, 1.34 x 10^23 atoms.