Balancing a chemical equation is much less painful than it seems. The process is pretty self explanatory, you need to make sure that equal amounts of molecules of an element are present on each side of the equation, therefore making it ‘balanced’. Think of the chemical equation as a see-saw. If equal weight is on each side of the see-saw, the weights will balance out and the see-saw will become level to the ground. Metaphorically, your goal in balancing a chemical equation is getting equal weight on each side of the see-saw.

In this process, you will need to know about how to find the charges of an ion of a specific element, the setup of a basic binary decomposition (which is what I will use as an example throughout this article), what a diatomic molecule is, and the purpose of a coefficient in a chemical equation.

First, we will go over the ion charges. For a non-metal, it is determined by it’s position on the periodic table. More specifically, it is determined by its group. A group is a column on the periodic table.

Figure A shows the charges of the non-metals in relation to their group. Charges are determined by the amount of valence electrons (electrons on the outer-most level of its electron cloud) an element has, but we won’t go into any more detail than that.

The reason you need this information is to write the equation in the first place. For example, we all know that water is H2O in chemical terms. But why? Simply look at the charges. Water is composed of Hydrogen and Oxygen. The charge of hydrogen is +1, and the charge of oxygen is -2. Therefore, for the charges to equal out, you need 2 hydrogen molecules and 1 oxygen molecule, hence H2O (when you only have one of a molecule, a subscript is unneeded, as it is assumed there is one of the molecule). When you have two hydrogen molecules, their combined charge is +2, which equals out the charge of oxygen which is -2. Let’s look at Carbon Dioxide, or CO2. The charge of Carbon is +4 (for our purposes), and the charge of oxygen is -2 (as we learned in the last example.) To equal out the charges, you need two oxygen molecules, so you get one C molecule and 2 O molecules, or CO2.

I mentioned earlier that I would use a simple decomposition throughout this article. The format for this equation is AB -> A + B. Everything on the left side of the reaction is what you will start with, the arrow (->) means ‘yields’ (produces), and everything on the right side of the reaction is what you will end with. Let’s look at NaCl (table salt). Apply what you learned in the last graph to NaCl. Na has a charge of +1, and Cl has a charge of -1, therefore you only need one of each molecule for the charges to balance out. When you plug NaCl into the decomposition equation, it looks like this:

NaCl -> Na + Cl

But, this eqaution isn’t balanced.

The next thing that needs to be discussed is a diatomic element. A diatomic element is an element that, when alone, needs to ‘have a buddy’ so to speak. The diatomic elements are Nitrogen, Oxygen, Flourine, Chlorine, Bromine, Iodine, and Hydrogen. There is an Extremely simple way to remember this. There is hydrogen, which is the first element. That’s easy. Finding the others is where you will apply this trick:

There are 7 diatomic elements. Aside from hydrogen, they start on the 7th element, and make the shape of a 7 on the periodic table. Look at Figure B:

All of the elements surrounded in red are diatomic elements.

If you remember this trick, the diatomic elements should be no trouble at all.

Now, let’s go back to the equation, NaCl -> Na + Cl.

Notice that Cl is a diatomic, and it is not combined with anything. The equation would actually be

NaCl -> Na + Cl2.

The last step in this process is actually balancing the equation, and to do this you will use Coefficients. In algebra, a coefficient indicates multiplication (i.e. 2x is 2 times the variable ‘x’). A coefficient serves the same purpose in chemistry. If a coefficient is placed in front of an element in the equation, it multiplies the number of molecules. If an element is in a compound, you need to add the coefficient to the entire compound. In other words, you Can’t only place the 2 in front of the Cl (Na2Cl is wrong). If a coefficient is in front of a compound, it needs to be applied to the entire compound.

How will this help us? Remember that the purpose of balancing a chemical equation is to get an equal number of molecules on each side. If you count the molecules present in our current equation, there is 1 Na and 1 Cl on the left, while there is 1 Na and 2 Cls on the left. You will use coefficients to get the number of molecules equal.

The best way to balance an equation is to work left to right. Since there is 2 Cl molecules on the right side, you will need to have 2 on the left side as well. To do this, add a coefficient. You have one Cl on the left and you need 2. To get there, you would add a coeffient of 2 to the entire compound of NaCl.

So far, the equation would look like this:

2NaCl -> Na + Cl2

The coefficient multiplies the number of Na molecules and Cl molecules on the left side by two. The current amounts of molecules is 2 Na molecules and Cl molecules on the left, and 1 Na molecule and 2 Cl molecules on the right. Now the Na molecules are uneven. To even them out, you need to add a coefficient on the right to make the number of Na molecules equal 2. This can be achieved by adding a coefficient of 2 to the lone Na molecule on the right side, like so:

2NaCl -> 2Na – Cl2

This is a balanced chemical equation. There are two of each molecule on each side.

Alright, review. Let’s do the decomposition of water.

H2O -> H + O

There are two hydrogen molecules and one oxygen molecule because hydrogen has a charge of one and oxygen has a charge of two. Two hydrogen molecules are needed to even out the charges.

H20 -> H2 + 02

Both hydrogen and oxygen are diatomic elements, and both are not part of a compound, so both need two molecules.

2H2O -> 2H2 + O2

A coefficient is needed on H2O to balance the oxygen molecules, and a coefficient is then needed in front of the hydrogen molecules to balance them out.

This equation is balanced.

I really hope this helped with this essential process. Thanks for taking the time to give this a read.

-Kevin F