Answer:The center will be quite smaller in magnesium than in gold thus the alpha particle will scatter to a lesser degree and the experiment may not yield a meaningful result.
Explanation:
Gold has seventy nine protons and magnesium has only twelve protons. Gold atoms are quite much more massive than magnesium atoms. This implies that if magnesium atoms were used in Rutherford's experiment, the number of protons will be too few to give a reasonable result since the atom is quite small. A larger atom, having a larger centre is required in order to have meaningful scattering of alpha particles.
