4. The left side of the equation contains the reactants, which interact to form the new substances, or products. The products are on the right side of the equation.
Chemical equations must be balanced. In other words, you must have the same number of each atom in the reactants as you do in the products.

5. The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction.
Consequently,
chemical equations
must be balanced.

6. To balance an equation, you may have to insert a coefficient in front of a compound.
Example: 2 MgCl2
Any coefficient that is inserted in front of a compound applies to all of the elements in the compound.
Example : 2 MgCl2 = 2 Mg and 4 Cl
Subscripts are NEVER changed in order to
balance an equation.
Only coefficients can be changed
to balance an equation.