how many atoms are there in a drop of water?
In another way; there are 1.67 sextillion water molecules in a water droplet. Now, the number of atoms in one drop of water is 3x the number of molecules: atoms in a drop of water = 3 atoms/molecule x 1.67 x 1021 molecules. atoms in a drop of water = 5.01 x 1021 atoms.