How many oxygen atoms are in 1.00 g of quartz?

2.00 x 10^22 atoms The empirical formula for quartz is SiO2, so calculate the molar mass of quartz. Silicon = 28.0855 Oxygen = 15.999 Molar mass = 28.0855 + 2 * 15.999 = 60.0835 Now divide the mass you have of quartz by its molar mass 1.00 g / 60.0835 g/mol = 0.016644 mol Since you have 2 moles of oxygen atoms per mole of quartz, multiply by 2 0.016644 mol * 2 = 0.033288 mol Finally, multiply by avogadro's number to get the number of atoms. 0.033288 mol * 6.0221409e+23 atoms/mol = 2.00465 x 10^22 Round to 3 significant figures to get 2.00 x 10^22