In a chemical reaction, one or more substances change into different
substances. The atoms that make up the reactants recombine to form new
products (can be elements and/or compounds).
IN YOUR LAB INVESTIGATION:
What did you find out about the mass of the reactants compared to the mass of products?
REACTION 1
REACTION 2
In all balanced chemical reactions:
This can be represented by:
Steps for Balancing Chemical Equations
1. Write the
(unless already given to you).
2. Balance the number of atoms (or polyatomic ions) by counting the number of atoms (or
polyatomic ions) of each type in the reactant and product side. Balance chemical formulas by placing
in front of the formulas. Do not change the formulas!
3. Balance the
atoms.
4. Balance the
atoms.
5. If every coefficient can reduce to lowest terms, rewrite the equation
.
6. Double check by counting the number of atoms on both sides of the equation.
Example 1: Potassium reacts with diboron trioxide to produce potassium oxide and boron.
Word Equation:
Skeleton Equation
Balanced Equation:
Balancing an Equation with Polyatomic Ions
 Treat polyatomic ions as one unit, rather than individual atoms, providing that they do not change
during the reaction
Example 2: Copper reacts in silver nitrate to produce copper (II) nitrate and silver.
Word Equation:
Skeleton Equation:
Balanced Equation: