Nuclear Decay

What Nuclear Decay covers

Nuclear Decay is examined in Component 3, Light, Nuclei and Options, Section A, which every student sits. It covers spontaneous decay and the nature of α, β and γ radiation, nuclear transformation equations and nuclide notation, Distinguishing α, β and γ by ionisation, penetration and range, background radiation and gamma intensity with distance, activity, the becquerel and the decay constant and the exponential decay law and half-life.

The 6 subtopics

Each one has its own page.

• Spontaneous decay and the nature of α, β and γ radiationΒ⁻ particle, β⁺ particle and γ radiation.Open →
• Nuclear transformation equations and nuclide notationRecall questions on nuclide notation and what each number means, the changes in nucleon and proton number in alpha, beta-minus, beta-plus and gamma emission, writing balanced nuclear equations for named decays, and checking both numbers balance.Open →
• Distinguishing α, β and γ by ionisation, penetration and rangeRecall questions on the nature and charge of each type, their relative ionising power and penetrating power, the material and thickness that stops each, their range in air, how they behave in electric and magnetic fields, and the experiment that distinguishes them.Open →
• Background radiation and gamma intensity with distanceBackground radiation and plotted to test the inverse square law for γ radiation.Open →
• Activity, the becquerel and the decay constantActivity of a radioactive source and decay constant of a nuclide.Open →
• The exponential decay law and half-lifeHalf-life of a radioactive nuclide, plotted to turn exponential decay data into a straight line and how throwing a large number of dice models radioactive decay.Open →

What you need to know

Answer each one before you reveal it.

Take Nuclear Decay further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• The decay constant is the probability per second that a single nucleus decays, so a larger value vs The half-life is the probability per second that a single nucleus decays, so a larger value

  The decay constant is the probability per second that a single nucleus decays, so a larger value: faster decay. The half-life is the probability per second that a single nucleus decays, so a larger value: is the time for a large sample to fall to 50% of what it started with, so a larger value means the opposite.

• Radioactive decay being spontaneous vs Radioactive decay being random

  Radioactive decay being spontaneous: that nothing outside the nucleus triggers or influences it. Radioactive decay being random: it means that which particular nucleus decays next cannot be predicted.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What does it mean to say that nuclear decay is spontaneous?

   Model answer

   It means an unstable nucleus decays of its own accord, without being triggered by anything outside it. Nothing done to the sample causes a particular nucleus to decay.

2. 2

   Why is radioactive decay described as a random process?

   Model answer

   Every undecayed nucleus in a sample has the same constant probability of decaying in the next second, and there is no way to tell which one will go next. Only the average behaviour of a large number of nuclei is predictable.

3. 3

   State two external conditions that leave the rate at which a radioactive sample decays unchanged.

   Model answer

   Raising the temperature of the sample does not change it, and putting the atoms into a different chemical compound does not change it.

4. 4

   What is an α particle made of?

   Model answer

   An α particle is a helium-4 nucleus, made of two protons and two neutrons. It carries a charge of +2e.

5. 5

   What is a β⁻ particle, and where does it come from?

   Model answer

   A β⁻ particle is a fast-moving electron. It is created in the nucleus at the moment a neutron changes into a proton, so it did not exist inside the nucleus beforehand.

6. 6

   What is a β⁺ particle?

   Model answer

   A β⁺ particle is a positron, the antiparticle of the electron. It has the same mass as an electron and a charge of +e.

What is inside Levo

Six ways to work the same material.

Nuclear Decay revision questions

What does Nuclear Decay cover in Eduqas A-Level Physics?

6 subtopics: spontaneous decay and the nature of α, β and γ radiation, nuclear transformation equations and nuclide notation, distinguishing α, β and γ by ionisation, penetration and range, background radiation and gamma intensity with distance, activity, the becquerel and the decay constant and the exponential decay law and half-life. Each one has its own page with questions and model answers.

How is Nuclear Decay organised?

By the Eduqas A420QS specification, subtopic by subtopic, so it matches the order you are taught it in.