What would happen if the alpha particles directly hit the electrons in the gold foil in Rutherford's experiment? [closed]

Question

What would happen if the alpha particles directly hit the electrons in the gold foil in Rutherford's experiment? Would it get ionized or is there no probability of such a thing happening ?

Answer 1

The alpha particles used in this experiment have an energy of about $5.59\ \mathrm{MeV}$. This energy is too high; the alpha particle cannot simply capture two electrons and form a stable helium atom. By way of comparison, the first and second ionization energy of helium is $24.6\ \mathrm{eV}$ and $54.4\ \mathrm{eV}$, respectively.

Nevertheless, alpha particles cause frequent direct ionizations within a narrow diameter around a relatively straight track. This transfer of energy from the alpha particles to electrons causes an approximately continuous deceleration of the alpha particle. For $5.59\ \mathrm{MeV}$ alpha particles in gold, the initial electronic stopping power is about $220\ \mathrm{MeV\ cm^2\ g^{-1}}$. With a high density of $19.3\ \mathrm{g\ cm^{-3}}$, this means the initial linear energy transfer is about $4200\ \mathrm{MeV\ cm^{-1}}$. Therefore, the alpha particle loses its energy very quickly so that the range of the alpha particle in gold is very short. The continuous slowing down approximation (CSDA) range of $5.59\ \mathrm{MeV}$ alpha particles in gold is about $0.020\ \mathrm{g\ cm^{-2}}$. Considering the density of $19.3\ \mathrm{g\ cm^{-3}}$ again, the resulting range in gold is about $0.0010\ \mathrm{cm}$. (Clearly, the gold foil in the experiment had to be very thin.)

Only after the alpha particle has slowed down like this, it can finally capture two electrons and form a stable helium atom.

Answer 2

An alpha particle is basically a helium nucleus, with two positively charged protons and no electrons, the particle would react with any electrons it comes into contact with. However it likely depends on which electron it interacts with, and how close the particle comes that determine the outcome.

As ScienceDirect describes here -

In some cases, this force is not sufficient to separate the electron from the atom, but the electron is raised to a higher energy state and the atom is said to be “excited.” In other cases, the attractive force is sufficient to remove the electron from the atom (ionization). The closer an alpha particle passes near an electron the stronger the force and the higher the probability an ionizing event will occur.

In Layman's words, as the alpha particle gets closer to the electron, the more likely it is to take the electron from its orbital for itself. Electrons further form the nucleus of the gold atoms in the sheet would have been easier to ionize, as they'd have les ionisation energy.