The nuclide symbol for the radioactive isotope radon-222 is $^{222}_{86}\mathrm{Rn}$. A radon-222 atom decays by releasing an alpha particle (α-particle). Radon-222 is used in an alpha-particle scattering experiment. Fig. 8.1 shows a beam of alpha particles from radon-222 striking a very thin gold sheet in a vacuum. Diagram labels: radon-222, beam of alpha particles, thin gold sheet, vacuum, position J, position K.
(a)[2]
Describe the way the composition of an atom of radon-222 is different from that of an atom of radon-224.
(b)[3]
Radon-222 decays into a polonium (Po) isotope. Complete the nuclide equation for the decay of radon-222.
(c(i))[2]
An alpha-particle detector is shifted around near the gold sheet. The detector positions J and K are shown. Describe the reading when the detector is at position J and when it is at position K.
(c(ii))[2]
Explain what these observations show about the structure of a gold atom.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Neutron count differs / nucleon count differs” …