2.  A chemical equation is a short, easy way to show a chemical reaction using symbols instead of words.  A reactant is the substance you have at the beginning of the reaction.  A product is the new substance that formed during the reaction.

3.  The principle of conservation of mass states that in a chemical reaction, the total mass of the reactants must equal the total mass of the products.

4.  Write the equation. › H 2 + O 2 H 2 O  Count the atoms. › H 2 + O 2 H 2 O › 22 2 1

5.  Use Coefficients to Balance Atoms. › 2_H 2 +__ O 2 2_ H 2 O › 4 2 4 2  Look Back and Check › The left and right sides of the equation should be equal.

6.  Synthesis – two or more elements combine to make a more complex substance.  Decomposition – Compounds are broken into simpler products.  Replacement – When one element replaces another in a compound