Recognise the Elements that Form a Compound

A compound is a substance that contains two or more different elements joined together. Each compound has a name and also a unique chemical formula. The formula can be made up of symbols and numbers.

The chemical formula tells us what elements make up the compound, and also how many atoms of each element are in that compound. 

If there are numbers in a compound's formula, the numbers will be written smaller, and are placed slightly lower down than the symbols. 

H₂O

For example, if we take a look at the compound above with the chemical formula H₂O (do you recognise it - it's water!) we can tell quite a lot about the compound.

We can tell that it is made up of hydrogen (H) and oxygen (O). And we can also tell that there are 2 atoms of hydrogen for every atom of oxygen - that's what the little two means after the H.  

Let's have a look at some common compounds and try some questions.