ABSTRACT
The structure of the atom can be visualized as a miniature solar system, with the neutrons and protons taking the place of the sun at the centre or nucleus, and the electrons forming the orbital planets (see Figure 3.1 – for simplicity the electron orbits are shown lying in the same plane). The proton is a particle possessing a single positive charge, but the neutron, which has the same mass as the proton, is electrically neutral. The electron, whose mass is much smaller than that of the proton and neutron, has a single negative charge. Atoms are normally electrically neutral, having equal numbers of protons and electrons.
