Question

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

Answer 1

Rutherford's experiment:

• Rutherford performed an experiment, directing high-energy streams of α-particles from a radioactive source at a thin foil of heavy atoms of Gold, and to study the deflection caused to the α-particles, he placed a fluorescent Zinc sulfide screen around the thin gold foil.
• In heavy atoms like Gold, Platinum, etc., have a heavy nucleus carrying a large amount of positive charge.
• Thus, some ${\displaystyle \alpha }$-particles are easily deflected when they strike the nucleus.
• Also, one in twenty thousand incident alpha particles due to repulsion confirmed the presence of a heavy and large positive charge in the gold atom.

The difference that would be observed in the results of Rutherford's experiment if a thin foil of light atoms like Aluminum is used:

• A foil of small atoms like Aluminum, having a very less number of positive charges will not be able to repulse a fast-moving alpha particle to return and at the maximum, it may deflect them at small angles.
• The number of ${\displaystyle \alpha }$-particles are deflected through small angles because of the large positive charge on the nucleus, hence If light atoms are used, their nuclei will be light, and moreover, they will have a small positive charge on the nucleus.
• Hence, in this observation, the return of alpha particles would not have been observed and the establishment of a nucleus would not have been made.