The Nucleus

Fig 5

The Nucleus of an atom consists of protons, and neutrons.  A proton has a charge of positive one while a neutron has no electric charge at all and both have a mass of one atomic mass unit.  These two particles are known as nucleons.  On the outside of the nucleus electrons can be found.  These electrons have a  charge of negative one and a mass that is negligible because of how small it is compared to the nucleons.  The discovery of the electron showed that the atom might have an internal structure.  It was originally thought to be a conglomerate or "plum pudding" as it was called.  But it was soon discovered using the gold foil experiment.  Some of the particles were scattered backwards.  Because of these results, it was theorized that the nucleus was like an electron moon orbiting a neutron and proton planet.  Using this model, it is easier to understand how the different reactions occur.

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