The more that you study science the more that you find that everything is too long. You could say that “carbon plus oxygen gives carbon dioxide” but that would be laborious and tedious to write out each time – especially when reactions get complicated. Instead chemists shorten it to a formula like this: 

Before we throw you into writing your own chemical formulae, here are four rules:

1.      The first letter of every element must start with a capital letter.

2.      Reactants are always on the left side, and products are always on the right (reactants are what you put in and products are what you get out)

3.      Never put an equals sign. It’s always an arrow.

4.      When writing the number of the element (O₂ means two Oxygens) always write the number in subscript.

Using these rules, if we had Hydrogen (H₂) reacting with Oxygen (O₂) to produce Water (H₂O) this would be the result: 

Later in this book we will show you how to work out chemical formulae using our old friend, the Periodic Table. But for now, we’ll keep it simple – if you eat the entire pie at once, you’ll be bloated.                                                                                                                                          Conveniently, chemists add prefixes to the start of substances to tell you how many of an element there is in a substance. We will start by learning the first five prefixes:

1.      Mono-

2.      Di-

3.      Tri-

4.      Tetra-

5.      Pent- 

So, if you had Carbon Monoxide (C0) you would know that you had one oxygen, or if you had Carbon Tetrafluoride (CFl₄) it would have four fluorine molecules.                               

Though, you must remember that you will not always be given the prefix. But if you can use it, do: it’s a damn side simpler and easier.