Basic Atom Structure
Protons, neutrons and electrons come together to form atoms, but they are not even distributed throughout the atom. Instead, the protons and neutrons concentrate at the centre of the atom. Together they form the nucleus of the atom. The electrons move around the outside of the nucleus very fast; so fast that you cannot pinpoint an electron at any one time. This is why we say that the electrons form an electron cloud around the nucleus.
Roll your mouse over the above image to see the labelled image. You will learn more about the structure of an atom in the upcoming Electron Structure section).