1. Balancing Equations In
Chemical Reactions

2. symbol
molecule
2H2 + O2 2H2O

3. symbol
molecules
2H2 + O2 2H2O

4. molecules
2H2 + O2 2H2O

5. 2H2 + O2 2H2O
molecules
Coefficient – tells us how many molecules

6. molecules
2H2 + O2 2H2O
Coefficient – tells us how many molecules

7. molecules
2H2 + O2 2H2O
This is a coefficient as well which means there is one molecule.

8. 2H2 + O2 2H2O There are 2 - H2 molecules 1 - O2 molecule
Coefficient – tells us how many molecules
There are
2 - H2 molecules
1 - O2 molecule
2 - H2O molecules

9. Counting Atoms

10. 2H2
How many atoms are there?
2 - H2 molecules = 4 atoms of Hydrogen

11. 2H2 + O2 How many atoms are there?
2 - H2 molecules = 4 atoms of Hydrogen
1 - O2 molecule = 2 atoms of Oxygen

12. 2H2 + O2 2H2O How many atoms are there?
2 - H2 molecules = 4 atoms of Hydrogen
1 - O2 molecule = 2 atoms of Oxygen
How many atoms are on the right side of the equation?

13. 2H2 + O2 2H2O How many atoms are there?
2 - H2 molecules = 4 atoms of Hydrogen
1 - O2 molecule = 2 atoms of Oxygen
2 - H2O molecules = 4 atoms of Hydrogen
How many atoms are on the right side of the equation?

14. 2H2 + O2 2H2O How many atoms are there?
2 - H2 molecules = 4 atoms of Hydrogen
1 - O2 molecule = 2 atoms of Oxygen
2 - H2O molecules = 4 atoms of Hydrogen
2 atoms of Oxygen
How many atoms are on the right side of the equation?