1. and
the MOLE

2. Using Mass to Count Things
Atoms are so tiny it is impossible to count # atoms in only 1 gram of matter
use mass to “count” atoms

3. Counting by mass You have a pile of nails that weighs 1227 g
One nail has a mass of grams
How many nails are in the pile?
1227g = nails
0.450 g per nail
[Let’s call it 2730 nails]

4. What is a mole?
Not this kind of mole!

5. The MOLE Unit used to “count” # atoms Count-by-mass technique
Defined: # atoms in 12.0 grams of C-12
This is the STANDARD!
12.0 g of C-12 has X 1023 atoms

6. The MOLE
1 mole of any element has 6.02 X 1023 particles
This is a really big number – It’s so big because atoms are really small!

7. 6.02 X 1023 = Avogadro’s Number
One mole of water = 6.02 X 1023 water molecules
One mole of gorillas is 6.02 X 1023 gorillas
One mole of He atoms is 6.02 X 1023 He atoms
One mole of anything is 6.02 X 1023 of that thing

8. Similar Words Pair: 1 pair of shoelaces = 2 shoelaces
Dozen: 1 dozen oranges = 12 oranges
Gross: 1 gross of spider rings = 144 rings
Ream: 1 ream of paper = 500 sheets paper
Mole: 1 mole of Na atoms =
6.02 X 1023 Na atoms

10. Equalities 1 mole of C-12 = 12.0 grams of C-12
6.02 X 1023 atoms of C-12

11. 0.5 mole of C-12 =
6.0 grams of C-12
3.01 X 1023 atoms of C-12

12. Equalities 1 mole C-12 = 12.0 g C-12 6.02 x 1023 atoms C-12
0.25 mole of C-12 =
3.0 grams of C-12
1.50 X 1023 atoms of C-12

13. Equalities 1 mole C-12 = 12.0 g C-12 6.02 X 1023 atoms C-12
2 moles of C-12 =
24.0 grams of C-12
12.04 X 1023 atoms C-12
[= X 1024 atoms C-12]
Can this help with other elements?

14. What is the mass of 1 mole of Mg (magnesium)?
1 mole of Mg = 24 grams

15. MOLAR mass for any element:
molar mass of any element = atomic mass in g/mole
1 mole Ne = 20 g/mol [= 6.02 X 1023 atoms]
1 mole Ar = 40 g/mol [= 6.02 X 1023 atoms]
1 mole Kr = 84 g/mol [= 6.02 X 1023 atoms]