1. Find the molar mass of Lithium:
* The molar mass of Lithium (Li) is approximately 6.941 g/mol.
2. Calculate the number of moles:
* Divide the mass of the sample by the molar mass:
* Moles of Li = (20 g) / (6.941 g/mol) ≈ 2.88 mol
3. Use Avogadro's number:
* Avogadro's number tells us there are 6.022 x 10^23 atoms in one mole of any substance.
* Multiply the number of moles by Avogadro's number:
* Number of atoms = (2.88 mol) * (6.022 x 10^23 atoms/mol) ≈ 1.73 x 10^24 atoms
Therefore, there are approximately 1.73 x 10^24 atoms present in a 20 gram sample of Lithium.
