In a modern reconstruction of the Geiger–Marsden scattering experiment, a collimated beam of alpha particles (24He2+^{4}_{2}\text{He}^{2+}24He2+) is directed at an extremely thin sheet of platinum foil.
Explain how the observed distribution of deflection angles of the alpha particles provides evidence for:
the mass of the atom being concentrated in a tiny nucleus.
the nucleus having a positive charge.