My name is Doctor Womac and I am going to teach you all about chemical formulae. A chemical formula is a way to describe the chemical elements that make up a particular chemical compound. It consists of chemical symbols to covey the elements and numbers to show the number of atoms of each element. H2SO4 is the chemical formula for sulphur for example. The charge of an ion can be displayed in superscript, such as Au2+. This concludes my lesson. I must rush off home now because I have a problem with some radioactive phosphate.