Writing reactions

When a reaction occurs, we can record on paper what has happened, but we do so in very specific ways. For example, when barium nitrate reacts with sodium sulfate, the reaction that occurs is written this way:

Here is the same reaction, with explanations for all of the numbers that you may or may not recognize:

When reactions are written in this manner, there are a few very important rules that must be followed:

• The reactants (the things that are reacting together) are always on the left side
• An arrow leads from the left to the right and signifies that a change is occurring.
• The products (the things that are formed in the reaction are always on the right side
• The reaction must be balanced. That means that there must be the same number of atoms of each element on both sides of the reaction.
• Formulas MUST be written correctly according to the defined practice
• Reactions are balanced by adding coefficients (by changing how many or each molecule are involved in the reaction not by changing the formula itself