The Nuclear Model (Also seen in GCSE Physics 1 and 2)

We know from Rutherford’s experiment that the structure of an atom consists of positively charged protons and neutral neutrons in one place called the nucleus. The nucleus sits in the middle of the atom and has negatively charged electrons orbiting it. At GCSE we used charges and masses for the constituents relative to each other, the table above shows the actual charges and masses.

Almost all of the mass of the atom is in the tiny nucleus which takes up practically no space when compared to the size of the atom. If we shrunk the Solar System so that the Sun was the size of a gold nucleus the furthest electron would be twice the distance to Pluto.

If the nucleus was a full stop it would be 25 m to the first electron shell, 100 to the second and 225 to the third.