1. Relating Mass to Number of Atoms The Mole!

2.  Mole is a quantity  Mole is the amount of substance that has as many particles as exactly 12 g of carbon-12  Moles are essential to understand chemical reactions and stoichiometry

3.  What is the mass in grams of 3.50 mole of the element copper?

4.  A chemist produced 11.9 g of aluminum. How many moles of aluminum were produced?

5.  Avogadro’s number tells how many particles are in a mole  Experimentally determined to be 6.0221367 x 10 23 particles/mole  We use: 6.022 x 10 23 particles/mole

6.  Mass of one mole of a pure substance  Since amu are defined based on carbon-12 and so are moles, one mole of an element has the average atomic mass in grams  Usually written in units of g/mole  Example: molar mass of Fe is 55.847 g/mole

7.  Molar mass can be used to convert from grams to moles and vice versa  Sample problem 3-2 p 82  Sample problem 3-3 p 83

8.  Since we know the number of particles in one mole, we can use it with moles or mass  Sample problem 3-4 p 84 ◦ How many moles of silver are in 3.01 x 10 23 atoms of silver?  Sample problem 3-5 p 84 ◦ What is the mass in grams of 1.20 x 10 8 atoms of copper?