What do you think would happen if $\alpha$-particles were replaced with negatively charged particles in Rutherford's gold foil experiment? [Pg. No. 144]

If $\alpha$-particles were replaced by negatively charged particles such as electrons in Rutherford's gold foil experiment, the results would be different. Electrons would be attracted towards the positively charged nucleus and repelled by the atomic electrons, so their paths would bend towards the nucleus instead of being repelled away from it. However, electrons are much lighter than $\alpha$-particles, so they would be easily deflected by both the nucleus and the electrons present in the atom. Their scattering pattern would therefore be irregular and less clear. Hence, negatively charged particles would not be suitable for showing the presence of a small, dense, positively charged nucleus in the same way as $\alpha$-particles did.