Nuclear Model

Key Stage 4

A image of an atom in the Nuclear Model showing a small nucleus at the centre and an electron orbiting around the nucleus.

The Nuclear Model is a model of the atom which suggests there is a positively charged nucleus in the centre of an atom with electrons orbiting around the nucleus.

The Nuclear Model was first proposed by Ernest Rutherford after he successfully disproved the Plum Pudding Model of the atom using his alpha scattering experiment.

In the Nuclear Model most of the atom is empty space. The majority of the mass of the atom is concentrated in a small central nucleus. This central nucleus has a strong positive charge while negatively charged electrons orbit the nucleus.

In Rutherford's Alpha Scattering Experiment several observations about the path of alpha particles through a thin sheet of Gold foil that led to the development of the Nuclear Model:

Observation	Conclusion
Most of the alpha particles pass straight through the foil.	The atom must be mostly empty space.
Some of the alpha particles were deflected by a small angle.	The mass of the atom must be concentrated in an extremely small volume in the centre.
A very small number of alpha particles came back in the direction of the detector. (Deflected more than 90°.)	The centre of an atom must have a strong positive charge. The electrons must not be in the centre of the atom, they must be orbiting the nucleus.