1. Chemical Reactions Equations

2. Chemical Equations and Reactions Law of conservation of mass – during a chemical reaction, the total mass of the reacting substances (the reactants), is always equal to the total mass of the resulting substances (the products)

3. Word Equation The simplest form of a chemical equation Methane + oxygen  carbon dioxide + water

4. Skeleton Equation Summarizes a chemical reaction by using symbols CH 4 + O 2  CO 2 + H 2 O

5. Balancing Chemical Equations Step 1: look at the number of atoms on the reactants side of the equation. Step 2: look at the number of atoms on the products side of the equation. Step 3: Do the numbers match? If not, you will need to add a coefficient. Coefficient – a number written before the compound 2H 2 + O 2  2H 2 O

6. Balancing Chemical Reactions Step 4: Determine what state the reactants and the products are in. Remember The reactants and the products must always have the same number of atoms.

7. Writing Balanced Chemical Equations Write the skeleton equation Find an element or polyatomic ion e.g.- nitrate (NO 3 - ) that appears only once on each side of the equation, then balance those two terms Find another element that appears only once. Balance this element as well. Check for any terms that you have not looked at yet. Check the equation again.