Question

What do you think would be the observation if $\alpha$-particle scattering experiment is carried out using a foil of a metal other than gold?

Answer 1

Rutherford's scattering experiment:

• Scientist named Earnest Rutherford of New Zealand challenged Thomson's atomic concept in $1911$ with his gold foil experiment.
• His research demonstrated the existence of an atom's small, massive nucleus. As a result, it rejected Thomson's atomic model.
• Rutherford chose a gold foil because he needed a thin coating.
• Fast-moving alpha particles were forced to fall on a tiny piece of gold foil in his experiment.
• The energetic alpha particles are composed of helium ions with a $+2$ charge.
• The light bursts saw the particles that were created as they collided with a zinc sulfide $\left(\mathrm{ZnS}\right)$ screen.
• He anticipated that the alpha particles would impact the fluorescent screen and easily pass through the gold foil

Reason for using Gold foil:

• Gold is a heavy metal with a flexible nucleus that can be readily formed into a thin foil that scatters alpha particles because of its density.

What if any other metal was used:

• As an alternative, producing thin foil from other metals is much more expensive and complex than doing so with gold, and if we use a metal sheet with a greater thickness, the outcome could not be as expected.
• More particles would bounce back if we used a thick foil, making it impossible to determine with such confidence where the positive mass of the atom is located.
• The fundamental issue is that, except for hydrogen and helium, all metal nuclei are heavy and can deflect alpha radiation when converted into thin foil.
• Hence, gold was preferred over the other metal for Rutherford's experiment