1. The Law of Conservation of Mass
States that matter can neither be created nor destroyed.
Atoms do not disappear in a chemical reaction! – they rearrange themselves into the new substances (products).
Equations have to be balanced with coefficients (representing the # of molecules) in order to support this law.
The # of atoms of each element must be the same on both sides of the equation!
Multiply the coefficient by the subscript to calculate number of atoms.

2. Photosynthesis Equation Example:
H C C6H
unbalanced
6H C C6H
balanced

3. Steps to Balance an Equation!
Count the atoms for each element on both sides of the chemical equation.
Add Coefficients to balance the total number of like atoms for each side of the chemical equation.
If Subscripts are present, multiply the coefficient with any subscripts in the chemical formula.
Subscripts should always remain the same.
Recount the atoms on both sides of the equation.
If the total number of atoms for both sides of the equation is not balanced, adjust coefficients as necessary.