Question: how many atoms are there in a drop?
Answer: Put another way, there are 1.67 sextillion water molecules in a water drop. Now, the number of atoms in a droplet 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.