m ( Mg ) = 80.45 g We can find the molar mass of magnesium in the Periodic table: M ( Mg ) = 24.31 g / mole n = 80.45 g : 24.31 g/mole = 3.31 moles N a ( Avogadro`s constant ) = 6.02 * 10 ^23 N = Na * n = 6.02 * 10 ^24 * 3.31 = 19.926 * 10 ^23 Answer: There are 1.9926 * 10 ^24 atoms.
