1. The MOLE The term “MOLE” is used to count numbers of atoms and molecules A “MOLE” represents a number 6.02 x 10 23 (scientific notation)

2. 6.02 x 10 23 - Avogadro’s Number The mole, 6.02 x 10 23, is referred to as Avogadro's number. In 1811, Amadeo Avogadro, an Italian physics professor, hypothesized that “equal volumes of different gases contain equal numbers of atoms” Scientists later used Avogadro's hypothesis for all molecules. Molecular masses of all substances contain the same number of molecules: 6.02 x 10 23.

3. A Mole is a BIG Number For example: A dozen eggs will make a large omelet, but a mole of eggs will fill all of Earth’s oceans 30 million times It would take 12 billion chickens laying 12 eggs per day about 12 billion years to lay 1 mole of eggs

4. A Mole is a BIG Number It would take 12 billion chickens laying 12 eggs per day about 12 billion years to lay 1 mole of eggs

5. Again, a mole is 6.02 x 10 23 items That is 602,000,000,000,000,000,000,000 (that is 602 sextillion) So why would we ever use such a big number?

6. How Many in a Mole? So why would we ever use such a big number? A mole is 6.02x10 23 items That is: 602,000, 000 602 sextillion!

7. Counting Atoms and Molecules Atoms and molecules are very tiny – it takes a LOT of them to make even a single milliliter!  For example, one milliliter of water would have: 3.34x10 22 atoms of oxygen 6.68x10 22 atoms of hydrogen

8. “MOLE” is Used to Count Atoms and Molecules Atoms and molecules are very tiny it takes a LOT of molecules to make a milliliter Instead of counting …illions and …illions it's much simpler to count in “moles” It’s easier to say “1 mole” than to say “six-hundred-and-two-sextillion”

9. Elemental Molar Masses For any element, the molar mass is equal to its average atomic mass.  Found on the periodic table  Measured in grams per mole (g/mol)

10. Diatomic Elements Most elements are listed as single atoms when in the elemental form, but seven of them are not. You need to know which elements are diatomic!  Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine and Iodine!

11. Diatomic Elements Whenever one of these elements is by itself it will always be in twos!  Example: N 2 is nitrogen gas This does NOT affect these elements when they are in a compound, only when by themselves!

12. Mole Calculations Use dimensional analysis to solve mole problems. Points to remember:  Always go to moles first!  Write your units at every step!

13. Example 1 How many moles are in 24.6 g of neon? Neon is 20.180 g/mol

14. Example 2 What is the mass of 2.50 moles of hydrogen gas? Hydrogen is diatomic, so it is H 2 Molar mass is 2.016 g/mol

15. Example 3 How many atoms are in 3.95 moles of beryllium?

16. Example 4 How many moles are in 5.15x10 23 atoms of sulfur?

17. Example 5 What is the mass of 2.00x10 24 atoms iron?

18. Example 6 How many atoms are in 15.4 g lithium?