# Chemistry - Writing Formulae and Balancing Equations

The following 4 steps show you how to write and balance chemical equations:

Write the equation in words

Write the equation in symbols

Check the equation is balanced

Add state symbols

Balancing equations means that you have the same number of atoms on both sides of the equation. The reason for this is because atoms are not lost during a chemical reaction and none are created.

Remember – multiply the whole formulae whether it is an element or a molecule – do not ever change the formulae.

Here is an example:

Step 1 – Magnesium + Oxygen à Magnesium oxide

Step 2 – Mg + O 2 à MgO

Step 3 – 2Mg +O 2 à 2MgO

Step 4 – 2Mg (s) + O 2(g) à 2MgO (s)

Because oxygen has two atoms on the left side of the equation (the reactants side), multiply by 2 the magnesium oxide (MgO) so that there are 2 oxygen atoms on the right side of the equation (the products side). However, now there are two magnesium (Mg) atoms on the right, so multiply the magnesium by 2 on the left to balance the equation.