1. Scientific Notation and moles  atoms

2. Why Scientific Notation?
In chemistry, we will often times run into very big or small numbers
Single gram of hydrogen has about hydrogen atoms
This is annoying

3. Scientific Notation
Easy way to represent very large or very small numbers.
Keep all numbers that are significant!
A number between 1 and 10 multiplied by the appropriate power of 10.
A positive exponent-- A very large number
A negative exponent– A very small number

4. Scientific Notation Practice
1,200
296,000
93,000,000
1,500,000
1.2 x 103
2.96 x 105
9.3 x 107
1.5 x 106
0.0420
0.0003
2.57 x 10-4
1.2 x 10-6
4.20 x 10-2
3 x 10-4

5. Practice with Sci Notation
Convert the following into scientific notation:
3,021,000,000
2,100,000
502,000
Convert the following to standard notation:
6.02 x 108
4.5 x 10-2
1.00 x 10-6
7 x 109

6. A. What is the Mole? VERY A large amount!!!!
A counting number (like a dozen)
Avogadro’s number
1 mol = 6.02  1023 items
A large amount!!!!
VERY

7. HOW LARGE IS IT???
1 mole of hockey pucks would equal the mass of the moon!
1 mole of basketballs would fill a bag the size of the earth!
1 mole of pennies would cover the Earth 1/4 mile deep!

8. B. Dimensional Analysis
The “Factor-Label” Method
Units, or “labels” are canceled, or “factored” out

9. Convert between atoms and moles
Now we can convert using our new unit!
1 mole = 6.02 x 1023 atoms
So we can use these two fractions to help…
1 mole_____
6.02 x 1023 atoms
6.02 x 1023 atoms
1 mole

10. C. Molar Conversion Examples
How many moles of carbon would you have if there are 4.2 x 1022 atoms of Carbon?
1 mole C
6.02 x 1023 atoms C
4.2 x 1022 atoms C x
= mol C

11. C. Molar Conversion Examples
How many atoms of oxygen would you have if there are 3.5 moles of Oxygen?
6.02 x 1023 atoms O
1 mole O
3.5 moles O
= 2.1 x 1024 atoms O

12. Practice mole-atom conversions
Complete the calculations:
How many moles of Iron would you have if you have 1.45 x 1030 atoms of Iron?
How many atoms of Copper would be present in 54.2 moles of Copper?

13. B. Molar Mass Mass of 1 mole of an element or compound.
Atomic mass tells the...
atomic mass units per atom (amu)
grams per mole (g/mol)
Round to 2 decimal places

14. B. Molar Mass Examples carbon aluminum zinc 12.01 g/mol 26.98 g/mol

15. C. Molar Conversion Examples
How many moles of carbon are in 26 g of carbon?
26 g C
1 mol C
12.01 g C
= 2.2 mol C

16. C. Molar Conversion Examples
How many grams of Sodium are present in 2.8 mol Sodium?
2.8 mol Na
22.98 g Na
1 mol Na
=64.34 g Na

17. Homework Tonight 1 mole = 6.02 X 1023 atoms or molecules
Determine if you are using grams or atoms.
1 mole = 6.02 X 1023 atoms or molecules
1 mole = # grams from periodic table
Warning! You MAY need to use BOTH!
Follow your units...they will show you the way