# Activity and half-life calculations

I can interpret radioactive half-life graphs and make calculations using values of half-life.

# Activity and half-life calculations

I can interpret radioactive half-life graphs and make calculations using values of half-life.

## Lesson details

### Key learning points

- The amount (or activity) of a radioactive isotope repeatedly falls by half in equal amounts of time.
- A radioactive half-life graph shows the amount (or activity) of a radioactive isotope plotted against time.
- In 2 half-lives the amount (or activity) of a radioactive isotope falls to ½ × ½ = ¼ as much.
- In 3 half-lives the amount (or activity) of a radioactive isotope falls to ½ × ½ × ½ = 1/8 as much, and so on.
- Radioactive isotopes with short half-lives decay quickly, emitting most radiation over a short period of time.

### Common misconception

It is impossible to predict outcomes for random events such as radioactive decay.

Use analogies to show that random nuclear decay can lead to predictable outcomes, such as the randomness in the order popcorn kernels pop, but the predictability of how quickly all the popcorn takes to cook.

### Keywords

Activity - the number of decays per second; it is measured in becquerels (Bq)

Radioactive isotopes - contain unstable nuclei that will decay over time and emit ionising radiation

Radioactive half-life - the time taken for the activity of a sample of a radioactive isotope to halve

### Content guidance

- Depiction or discussion of sensitive content

### Supervision

Adult supervision recommended

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Video

Loading...

## Starter quiz

### 6 Questions

0 hours

10 hours

20 hours

30 hours

## Exit quiz

### 6 Questions

0 mins

5 mins

10 mins

15 mins

20 mins

25 mins