Question

In the Gold foil experiment, why can't helium ions mix with gold atom electrons?

Answer 1

Rutherford's Experiment:

• Rutherford fired alpha particles at thin gold foil to test this idea and observed how they dispersed.
• In this experiment, Rutherford demonstrated that the atom was mostly empty space, with the nucleus at its center and electrons rotating about it.

Gold Foil Experiment:

• It's possible that helium ions mix with gold atom electrons to form ${\mathrm{He}}^{+}$ and neutral gold atoms.
• Mass spectrographic devices cannot detect the presence of such reduced helium particles
• However, only the helium ion in gaseous form and the ionized electron may combine.
• The alpha particles from the radioactive nuclei ${\mathrm{Ra}}_{226}\mathrm{and}{\mathrm{Ra}}_{222}$ have kinetic energies of $4.86\mathrm{eV}\mathrm{and}5.59\mathrm{eV}$, respectively.
• The threshold energy of gold metal is $5.447\mathrm{eV}$, while the ionization energy of gold atoms is$9.22\mathrm{eV}$.
• As a result, the alpha particle lacks sufficient energy to liberate the electron from gold atoms for combination and thus helium ions can't mix with gold atom electrons.