1. Relating Mass to Numbers of Atoms The MOLE

2. Is the SI unit for amount of a substance Abbreviated as mol Amount of a substance that contains as many atoms as there are in 12g of C-12.

3. Avogadro’s Number Idea is crucial in explaining the relationship between mass and number of atoms Number of atoms (particles) in a mole is known as Avogadro’s Number Equal to 6.02 x 10 23 (experimentally determined) The number of atoms in exactly one mole of a pure substance.

4. Molar Mass Alternative definition of the MOLE  Amount of a substance that contains Avogradro’s Number of particles The mass of one mole of a pure substance is called the molar mass of that substance.  The molar mass of an element contains one mole of atoms Used as a conversion factor in chemical calculations 2.00 mol He x 4.00 g He = 8.00 g He 1 mole He