Radioactivity | Edexcel GCSE Physics, Foundation tier (1PH0)

Radioactivity

304 questions
23 subtopics
Paper 1
Paper 1

Radioactivity is examined in Paper 1, Physics 1.

It covers the atom and the size of atoms, isotopes, atomic number and mass number, relative masses and charges of subatomic particles, electron orbits and energy levels, forming ions, and how the atomic model changed, types of ionising radiation, background radiation and detecting radioactivity, alpha, beta and gamma, and their penetrating power, beta-minus and beta-plus decay, effects of decay on atomic number and mass number, balancing nuclear equations, activity and the becquerel, half-life and the randomness of decay, half-life calculations, uses of radioactivity, and how danger depends on half-life, the dangers of ionising radiation, safety precautions, contamination and irradiation, radiotherapy, medical tracers and PET scanners, nuclear power and where nuclear energy comes from, fission of uranium-235 and the chain reaction, controlling a reactor and generating electricity, nuclear fusion and how it differs from fission and why fusion needs extreme conditions.

Sample questions from Radioactivity

Answer each one closed book first, then open the answer.

The atom and the size of atoms

Why is almost all the mass of an atom concentrated in its nucleus?

Show the answer
Protons and neutrons are nearly two thousand times more massive than electrons, and both sit in the nucleus.
Relative masses and charges of subatomic particles

A neutral atom has 15 protons. How many electrons does it have?

Show the answer
It has 15 electrons.
Types of ionising radiation

Which type of nuclear radiation is an uncharged particle thrown out of the nucleus?

Show the answer
Neutron radiation.
Alpha, beta and gamma, and their penetrating power

What material and thickness is needed to stop beta radiation?

Show the answer
About 3 mm of aluminium will stop beta radiation.
Balancing nuclear equations

How is a β⁻ particle written in a nuclear equation?

Show the answer
It is written as ⁰₋₁e, with a mass number of 0 and a charge of −1.
Half-life and the randomness of decay

Explain why the count rate measured from a source varies slightly between equal time intervals.

Show the answer
Decay is random, so the number of decays in each interval varies about the average value.
The dangers of ionising radiation

Why is even a low dose of ionising radiation still a risk?

Show the answer
It can cause a mutation in a single cell that later develops into a cancer.
Radiotherapy, medical tracers and PET scanners

Why is a gamma emitter, rather than an alpha emitter, chosen as a medical tracer?

Show the answer
Gamma radiation passes out of the body to be detected and does far less damage to tissue on the way.

The 23 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
The atom and the size of atoms	Protons, neutrons and electrons and where they sit, the tiny dense positive nucleus, atoms as mostly empty space, the sizes of atoms, molecules and nuclei in standard form, and the symbols <<, >> and ~.	14
Isotopes, atomic number and mass number	What atomic number and mass number count, finding neutrons by subtraction, reading nuclear symbols, what isotopes are, and why carbon-12 and carbon-14 react identically.	13
Relative masses and charges of subatomic particles	Relative masses and charges of the proton, neutron, electron and positron, why electrons add almost no mass, why a complete atom is neutral, matching numbers of protons and electrons, and how an extra electron makes a negative ion.	12
Electron orbits and energy levels	Electrons orbiting at fixed distances called energy levels, why outer electrons are held least tightly, moving between levels by absorbing or emitting electromagnetic radiation, why only certain energies are absorbed, and how atoms give out light or ionise.	11
Forming ions, and how the atomic model changed	Ions and ionisation, how atoms become positive ions, the plum pudding model, alpha particle scattering in Rutherford's laboratory, the nuclear and Bohr models, why models of the atom changed, and peer review and communicating scientific results.	20
Types of ionising radiation	The five types of radiation emitted by unstable nuclei, why radioactive decay is random and unaffected by conditions, what ionising radiation does to atoms, and why strongly ionising radiation loses energy and cannot travel far.	11
Background radiation and detecting radioactivity	Background radiation and correcting count rates for it, natural sources such as radon, rocks, food and cosmic rays, sources from human activity, doses for aircraft crew, and detecting radiation with photographic film, film badges and Geiger–Müller tubes.	18
Alpha, beta and gamma, and their penetrating power	What alpha particles, beta minus particles and gamma rays are, their mass numbers, atomic numbers and charges, their ionising and penetrating power, what stops each one, and identifying a source from what absorbs its radiation.	15
Beta-minus and beta-plus decay	What happens inside a nucleus during β⁻ and β⁺ decay, how the numbers of protons and neutrons, the charge and the mass number change, which nuclei decay each way, and the differences between the two decays.	12
Effects of decay on atomic number and mass number	How alpha, beta-minus, beta-plus, gamma and neutron emission each change mass number and atomic number, worked examples, and why a gamma ray often follows another decay.	14
Balancing nuclear equations	Balancing mass number and charge in a nuclear equation, finding an unknown nucleus or particle, and how β⁻ particles and positrons are written.	9
Activity and the becquerel	Activity as the number of nuclei decaying each second, why it falls over time and the shape of its graph, the becquerel and what 1 Bq means, and calculating decays or activity from counts over a time.	9
Half-life and the randomness of decay	Half-life defined by undecayed nuclei and by activity, the fraction left after one or two half-lives, and why random decay still gives reliable predictions for a large sample.	11
Half-life calculations	Activity or nuclei remaining after a number of half-lives, finding a half-life from a fall in activity or from a graph, and the percentage left after three half-lives.	9
Uses of radioactivity, and how danger depends on half-life	Alpha sources in smoke alarms, gamma for irradiating food and sterilising instruments, tracers, beta thickness gauges, treating tumours, and why half-life decides how dangerous a source or waste is.	18
The dangers of ionising radiation	How ionising radiation damages cells and DNA, high and low doses, keeping dose, time and closeness to a source low, and school laboratory precautions.	9
Safety precautions, contamination and irradiation	Protective clothing, screens, lead aprons, low medical doses and film badges, shielding gamma radiation with lead or concrete, irradiation versus contamination, why alpha sources are most dangerous inside the body, and precautions against contamination.	14
Radiotherapy, medical tracers and PET scanners	Treating tumours with external gamma beams or internal implants and their side effects, PET scanning with positron-emitting tracers, gamma ray pairs and glucose, tracers for checking kidneys, and why PET isotopes are made on site in a cyclotron.	19
Nuclear power and where nuclear energy comes from	Advantages and disadvantages of nuclear power, its waste, costs and public opinion, storing high-level waste, the three nuclear processes that release energy, energy from lost mass compared with chemical reactions, and decay powering spacecraft.	12
Fission of uranium-235 and the chain reaction	How absorbing a neutron triggers fission of uranium-235, the daughter nuclei, neutrons and kinetic energy released, balancing mass numbers in fission, controlled and uncontrolled chain reactions, and why a minimum mass of fuel is needed.	12
Controlling a reactor and generating electricity	The moderator and control rods and their materials, shutting a reactor down, how the coolant, boiler, turbine and generator turn fission energy into electricity, the sealed coolant loop, and handling and storing radioactive fuel rods and fission products.	18
Nuclear fusion and how it differs from fission	What fusion is, why joining small nuclei releases energy from lost mass, hydrogen fusing to helium in the Sun, and how fusion compares with fission in use, waste and temperature.	12
Why fusion needs extreme conditions	Electrostatic repulsion between nuclei, why high temperature and pressure let them fuse, conditions in the Sun's core, and why a fusion reactor on Earth is so hard to build and run.	12

Radioactivity is 304 of the 1,778 questions in the guide.Get the guide, £7

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.