So if people were the size of an atom, the entire population of the world would fit into a box about 1000th of a millimetre across. Presenter: Wow, teeny tiny. Well, is there a way to help us ...

It also tells us that chlorine has 18 neutrons (35 - 17) and, as the number of electrons and protons are equal in a neutral atom, chlorine also has 17 electrons. The relative mass of a nucleus is ...