Nuclear Physics

You will be able to

• Describe the alpha-particle scattering experiment and what was observed at small and large angles.
• Explain how the results show that an atom is mostly empty space with a small, dense, positively charged nucleus.
• Explain why the plum pudding model cannot account for alpha particles deflected through more than 90°.

You will be able to

• Determine the proton number, nucleon number and neutron number of a nuclide from its nuclide notation.
• Explain what isotopes are, using nuclides with the same proton number but different neutron numbers.
• Describe how an atom becomes a positive or negative ion by losing or gaining electrons.

You will be able to

• Describe the penetrating abilities of α, β and γ radiation using paper, aluminium and lead absorbers.
• Calculate a corrected count rate by subtracting the background count rate.
• Describe and explain the deflection of α, β and γ radiation in electric and magnetic fields.

You will be able to

• Write balanced nuclide equations for α-decay, β-decay and γ-emission.
• Predict the nucleon number and proton number of the daughter nucleus for each type of decay.
• Explain why γ-emission changes neither the nucleon number nor the proton number.

You will be able to

• Determine the half-life of an isotope from a decay curve or a count-rate graph.
• Calculate the fraction or number of nuclei remaining after a whole number of half-lives.
• Explain that radioactive decay is random, yet the half-life of a large sample is constant.

You will be able to

• Describe nuclear fission of uranium-235 and how its neutrons can start a chain reaction.
• Explain the roles of the control rods and the moderator in keeping a chain reaction steady.
• Describe nuclear fusion and explain why it needs a very high temperature.