GCSEAQACombined Science FoundationCombined Science HigherPhysics FoundationPhysics Higher

## Nuclear Radiation Revision

Radioactive decay is the emission of particles or electromagnetic radiation from radioactive elements. The emitted radiation can be both useful and dangerous.

Some nuclei are unstable and they release radiation as they change in order to become more stable. This is a process called radioactive decay

Radioactive decay is a random process. This means that you can’t predict when a single nucleus will decay.

Instead, we can measure the activity of a radioactive source. This is the rate at which the source of unstable nuclei decays and it is measured in becquerels $\text{(Bq)}$. $1\text{ Bq}$ is equivalent to $1 \text{ decay per second}$.

The count rate is the number of decays recorded per second by a radiation detector such as a Geiger-Muller tube

There are three main types of radiation you need to know. The table below summarises their properties:

 Type of Radiation Symbol What is it? How ionising is it? Absorbed By Alpha $(\alpha)$ $^4_2He\text{ or }^4_2\alpha$ $2$ protons and $2$ neutrons (a helium nucleus) Strongly ionising A few $\text{mm}$ paper Beta $(\beta)$ $^0_{-1}e\text{ or }^0_{-1}\beta$ High energy electrons Moderately ionising A few $\text{mm}$ aluminium Gamma$(\gamma)$ $\gamma$ Electromagnetic radiation Weakly ionising Many $\text{cm}$ lead
GCSECombined Science FoundationCombined Science HigherPhysics FoundationPhysics HigherAQA

## Nuclear Equations

Nuclear equations are used to represent nuclear decay.

The emission of alpha or beta radiation causes a change in the nucleus. You need to be able to work out the mass and atomic numbers of nuclei after radioactive decay by balancing the mass numbers and atomic numbers on both sides of nuclear equation.

Alpha Decay

Here is an example of alpha decay:

In alpha decay, the mass number decreases by $4$ and the atomic number decreases by $2$

Beta Decay

Here is an example of beta decay

There is no change in the mass number of the nucleus since beta-particles contain no neutrons. Beta-particles contain $1$ electron however, and so to balance the atomic numbers on both sides of the equation, the atomic number of the nucleus must increase by $1$. This turns the nucleus into a nitrogen nucleus.

Gamma Decay

Here is an example of gamma decay:

Gamma decay does not change the mass or atomic number because gamma particles have no mass

GCSECombined Science FoundationCombined Science HigherPhysics FoundationPhysics HigherAQA

## Nuclear Radiation Example Questions

Becquerel $\text{(Bq)}$.

Gold Standard Education

alpha, beta, gamma.

Gold Standard Education

One mark per correct line drawn.

Gold Standard Education

$175 = \, ? + 4$

So the missing value is $\bold{171}$.

Gold Standard Education

Because there is no change in the mass or atomic number.

Gold Standard Education

Your 2024 Revision Partner

@mmerevise

Product

## MME Premium Membership

### £19.99

/month

Learn an entire GCSE course for maths, English and science on the most comprehensive online learning platform. With revision explainer videos & notes, practice questions, topic tests and full mock exams for each topic on every course, it’s easy to Learn and Revise with the MME Learning Portal.