1. Describe and calculate half life
Learning Objective
To be able to:
Describe and calculate half life
Key Words:
Decay, radioactivity

2. Monday, 20 May 2019
Half-life
Date and title in books. You need a pen, pencil & ruler.
Starter Activity – 5 minutes Exam question

3. Learning Outcomes Draw graphs which can be used to calculate half life
Target 1-9
Define half life
(F/H)
Target 4-9
Calculate half life using given data
(H)
Target 5-9
Draw graphs which can be used to calculate half life
Extension: Application of Knowledge
Target 8/9
Explain the significant of a half-life, linking it to the uses for different radioactive isotopes
Learning Outcomes

4. Boardworks GCSE Science: Physics Radioactivity
What is ‘radiation’?
The term radiation (also known as nuclear radiation) refers to the particles or waves emitted by radioactive substances.
electron
Nuclear radiation comes from the nucleus of a radioactive atom.
An atom has electrons orbiting the outside and a central nucleus, which is made up of protons and neutrons.
proton
neutron
In a radioactive atom, the nucleus is unstable and so it emits particles or waves to form a more stable atom.
This process is called radioactivity or radioactive decay. It is a natural and completely spontaneous process.

5. What is radioactive decay?
Boardworks GCSE Science: Physics
Radioactivity
What is radioactive decay?
Teacher notes
This activity, summarising the three types of radiation, could be used to introduce the topic of radiation, as a plenary exercise or as a revision exercise.

6. What happens to radioactivity?
Boardworks GCSE Additional Science: Physics
Radioactive Decay
What happens to radioactivity?
Teacher notes
This five-stage animation explains why radioactivity decreases over time.

7. Boardworks GCSE Additional Science: Physics Radioactive Decay
What is half-life?
Radioactive decay is a spontaneous process that cannot be controlled and is not affected by temperature.
However, each radioactive element has its own particular decay rate, which is called the half-life.
The half-life of a radioactive element is the time
that it takes half the atoms in a sample to decay.
For example, the half-life of the isotope iodine-131 is 8 days.
This means that after 8 days half the atoms in a sample of iodine-131 have decayed. 8 days later half the remaining atoms have decayed and so on.

8. How is half-life calculated?
Boardworks GCSE Additional Science: Physics
Radioactive Decay
How is half-life calculated?
Teacher notes
This four-stage animation explains about half-life and how to calculate it from a decay curve graph.