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.
