2. The Mole 1 dozen = 1 gross = 1 ream = 1 mole = 12 144 500 6.02 x 10 23 That is a REALLY BIG number…

3. A mole is also called Avogadro’s Number 6.02 x 10 23 is called “Avogadro’s Number” in honor of the Italian chemist Amadeo Avogadro (1776-1855). Amadeo Avogadro I didn’t discover it. Its just named after me!

4. The Mole So how do we use the mole in Chemistry? There are exactly 12 grams of carbon- 12 in one mole of atoms of carbon-12. ( 6.02 x 10 23 atoms ) There are 6.94 grams of lithium in one mole of atoms of lithium. Go count em’ and mass em’ Notice, these are called atomic weights on your periodic charts (but this really isn’t a weight…)

5. Using the Mole We use the mole to convert a measured mass of an element to find the # of atoms that are present. Ex: Mass 12g of carbon and you know you’ll have 1 mole of carbon which is 6.02 x 10 23 atoms of carbon. (cool, eh?) This is much easier than trying to count individual atoms!!!

6. Calculations with Moles: Converting moles to grams How many grams of lithium are in 3.50 moles of lithium? 3.50 mol Li = g Li 1 mol Li 6.94 g Li 24.3 There are 24.3 grams of lithium in 3.50 moles of lithium.

7. Calculations with Moles: Converting grams to moles How many moles of lithium are in 18.2 grams of lithium? 18.2 g Li = mol Li 6.94 g Li 1 mol Li 2.62 There are 2.62 moles of lithium in 18.2 grams of lithium.

8. Calculations with Moles: Using Avogadro’s Number How many atoms of lithium are in 3.50 moles of lithium? 3.50 mol Li = atoms Li 1 mol Li 6.022 x 10 23 atoms Li 2.11 x 10 24 There are 2.11 x 10 24 atoms of lithium in 3.50 moles of lithium.

9. Calculations with Moles: Using Avogadro’s Number How many atoms of lithium are in 18.2 g of lithium? 18.2 g Li = atoms Li 1 mol Li6.022 x 10 23 atoms Li 1.58 x 10 24 6.94 g Li1 mol Li (18.2)(6.022 x 10 23 )/6.94

10. Read 6.2-6.3, pages 159-164 Page 164, do Focus questions 6.1-6.3, #1-4 Page 188, question 8 & 9, problem 10