1. Focusing Task (White Board)
How many protons, neutrons and electrons are in an atom of calcium?
What is the average atomic mass of phosphorus?
What is the difference between the mass number of an atom and its average atomic mass?

2. Chemistry Unit 6: Chemical Quantities Lecture 6.1
Moles & Molar Mass
Chemistry
Unit 6: Chemical Quantities
Lecture 6.1

3. Objectives Explain how the quantity “mole” is defined
State the number of particles contained in the quantity “mole”
Determine the molar mass of a molecule from its chemical formula and atomic masses

4. The Mole A word that stands for a number of items like:
Pair
Dozen
Quadruplet
Could stand for any items

5. The number of atoms in a 12 gram sample of the Carbon-12 isotope
How the Mole is Defined
One mole is:
The number of atoms in a 12 gram sample of the Carbon-12 isotope

6. How Many IS a Mole?
1 mol = x 1023
602,000,000,000,000,000,000,000
Why such a big number?
Because atoms are so VERY SMALL!!

7. Molar Mass
Definition: the mass of one mole of molecules or formula units
Example: What is the molar mass of Ca(OH)2?
Ca: 1 x g/mol = g/mol
O: 2 x g/mol = g/mol
H: 2 x 1.01 g/mol = g/mol
74.10 g/mol

8. Determining Molar Mass
Determine which atoms, and how many of each are contained within the chemical formula
Multiply the number of each type of atom in the chemical formula by the molar (atomic) mass of each
Determine the sum of the products in #2 above.

9. Counting Atoms
The subscript following an atomic symbol tells you how many
If there are parentheses, multiply the subscript inside the parentheses by the subscript outside the parentheses
If the atom is listed more than once in the formula, add them all together.

10. Practice Counting Atoms
CH4
Cu3(PO4)2
CH3COOH

11. Practice
Calculate the molar masses of the following chemicals: (show your work!)
FeO
NH4Cl
Cu3(PO4)2

12. Quick Quiz
How did scientists decide how many particles a “mole” would represent?
How many particles IS a “mole”?
How do you determine the molar mass of a chemical?
What is the molar mass of H2CO3?
What is the molar mass of Sn(C2H3O2)4?
A mole is the number of atoms found in a 12 g sample of carbon-12
A mole is equal to x 1023 particles (items)
Multiply the number of each atom in the chemical formula by its atomic mass, then add these together.
62.03 g/mol
g/mol

13. Write your summary and questions now