In Rutherford�s experiment, generally the thin foil of heavy atoms, like gold, platinum etc. have been used to be bombarded by the a-particles. If the thin foil of light atoms like aluminum etc. is used, what difference would be observed from the above results?

Important conclusions from the Rutherford experiment were drawn from the number and angle of reflection of the helium ions from the incident angle. Returning back of approximately one in twenty thousand incident alpha particles due to repulsion confirmed the presence of a heavy and large positive charge in the gold atom (Z =79).

A foil of small atoms like aluminum, having a very less number of positive charges (Z=13) will not be able to repulse a fast moving alpha particle to return. At the maximum it may deflect them at small angles.

Hence, the return of alpha particles would not have been observed and the establishment a nucleus would not have been made.