7 Radioactivity and particles

7.1

Use the following units: becquerel (Bq), centimetre (cm), hour (h), minute (min) and second (s)

Describe atomic structure using protons, neutrons and electrons, and use nuclide notation such as ¹²₆C for particular nuclei.

Know the terms atomic (proton) number, mass (nucleon) number and isotope

Know that alpha (α) particles, beta (β-) particles, and gamma (γ) rays are ionising radiations emitted from unstable nuclei in a random process

Describe alpha (α) particles, beta (β⁻) particles and gamma (γ) rays and distinguish them by penetrating power and ionising ability.

Practical: investigate the penetration powers of different types of radiation using either radioactive sources or simulations

Describe the effects on the atomic and mass numbers of a nucleus of the emission of each of the four main types of radiation (alpha, beta, gamma and neutron radiation)

Understand how to balance nuclear equations in terms of mass and charge

Know that photographic film or a Geiger-Müller detector can detect ionising radiations

Explain the sources of background (ionising) radiation from Earth and space

Know that the activity of a radioactive source decreases over a period of time and is measured in becquerels

Know the definition of the term 'half-life' and understand that it is different for different radioactive isotopes

Use the concept of the half-life to carry out simple calculations on activity, including graphical methods

Describe uses of radioactivity in industry and medicine

Describe the difference between contamination and irradiation

Describe the dangers of ionising radiations, including: • that radiation can cause mutations in living organisms • that radiation can damage cells and tissue • the problems arising from the disposal of radioactive waste and how the associated risks can be reduced

Know that nuclear reactions, including fission, fusion and radioactive decay, can be a source of energy

Understand how a nucleus of U-235 can be split (the process of fission) by collision with a neutron and that this process releases energy as kinetic energy of the fission products

Know that the fission of U-235 produces two radioactive daughter nuclei and a small number of neutrons

Describe how a chain reaction can be set up if the neutrons produced by one fission strike other U-235 nuclei

Describe the role played by the control rods and moderator in the fission process

Understand the role of shielding around a nuclear reactor

Explain the difference between nuclear fusion and nuclear fission

Describe nuclear fusion as the creation of larger nuclei resulting in a loss of mass from smaller nuclei, accompanied by a release of energy

Know that fusion is the energy source for stars

Explain why nuclear fusion does not happen at low temperatures and pressures, due to electrostatic repulsion of protons