To gain all of the marks, 4 different points must be made. To begin, state what is obvious:
The density of the gold nucleus is much greater than the density of the gold atom.
The next step is to discuss what this means. As the gold nucleus is inside of the gold atom, this implies that the majority of the mass of the atom is concentrated within the nucleus.As density is mass per unit volume, a high density but a small mass shows that the volume must be incredibly small. This shows the nucleus is small compared to the size of the atom.And finally, this shows that the atom contains a lot of empty space.