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.
81 exam-style questions on Edexcel GCSE Physics 6.1 Atomic structure and isotopes, covering 6.1.1 Structure of the atom, 6.1.2 Isotopes: atomic and mass number, 6.1.3 Sub-atomic particles: masses and charges, and 6.1.4 Electron orbits and energy changes. Each one has a worked solution and a mark scheme showing where the marks go.