P7 Radioactivity
Independent Learning
Introduction
In this chapter you will recap how the structure of the nucleus and how our model of the atom has changed as the evidence changed: from the plum pudding model, to the nuclear model and then Bohr model.
You will learn about the three types of nuclear radiation, alpha, beta and gamma, along with their properties and uses. In addition you will learn about the random nature of radioactive decay, what the term “half-life” means and how to find this using a graph of activity level against time. Higher tier students will perform calculations involving the relationship between the initial activity, current activity, and half-life.
GCSE Physics students will also cover how radiation is used in medicine, in addition to the processes of fission and fusion. You will also look at the different issues and dangers associated with using nuclear radiation.
Specification links
Set 2 &3 - All of section 6.4 (pages 139 to 143)
Task 1: Know
Task 1a: Use look, cover, write, check and quizlet to learn the answers to the core questions and the keywords for this topic.
Learn
Task 2: History of the atom
Task 2a: Watch the videos
Task 2b: Read through the slides and the BBC Bitesize pages
Task 2c: Make notes that:
Explain how the model of the atom has changed over time and what discovery led to that change.
Explain how Rutherford’s gold foil experiment provided evidence that atoms contain a nucleus.
Draw and label the plum pudding model and the nuclear models of the atom.
Compare the plum pudding and nuclear models of the atom
Task 2e: Complete and self mark the exam question
Task 3: Atoms and isotopes
Task 3c: Make notes that:
Define ion
Define isotope
Give the size of an atom in standard form.
Explain how the radius of the nucleus of an atom compares to the radius of the whole atom.
Explain how to calculate the number of neutrons in an atom and write an example.
Explain what effect changing the number of protons in an atom will have.
Task 3d: Use the periodic table to help you copy and complete this table:
Task 3e: Complete the 'BBC bitesize' quiz
Task 4: Types of nuclear radiation
Task 4a: Watch both of these videos:
Task 4b: Read through the slides and the BBC Bitesize pages
Task 4c: Make notes that:
Define irradiated
Define radioactive contamination
Give the 3 types of nuclear radiation
Explain what each type of radiation is made of.
Task 4d: Copy and complete this table (leave the uses column untill next lesson):
Task 4e: Complete the 'BBC bitesize' quiz
Task 4f: Complete and self mark the exam question
Task 5: Uses of nuclear radiation
Task 5c: Make notes that:
Explain how a smoke detector works and why alpha radiation is used for this purpose
Explain how beta radiation is used to help monitor the thickness when making aluminium foil and why beta radiation is used for this purpose
Explain why gamma radiation is used to sterilise food and medical instuments and why gamma radiation is used.
Explain what peer review is and the advantages of using it for scientific research.
Task 5d: Complete the exam question
Set2 &3 only: Complete the progress quiz
Task 6: Changes in the nucleus
Task 6c: Make notes that:
Explain why radioactive isotopes release energy.
Explain what happens to the nucleus of an atom during alpha, beta and gamma decay.
Write the general equations for alpha and beta decay.
Explain the process of neutron emission.
Give the general equation for neutron emission
Task 6d: Copy and complete the decay equations use the periodic table to help you. Check your answers using slides 24 and 30 when you are done.
Alpha emission
Beta emmision
6d: Complete the exam question
6e: Set 1 only: Complete the checkpoint quiz
Task 7: Activity and Half-life
Task 7b: Make notes that:
Define half-life
Draw and label the half-life graph on slide 16
Explain how half-life can be calculated using a graph.
Calculate the answers to the questions:
1. A radioactive isotope has a half-life of 15 hours. The initial activity is 400 Bq. Calculate the activity:
i) After 15 hours
ii) After 60 hours
Click the arrow on the right to check your answers
i) After 15 hours
1 half-life has passed. 400Ă· 2 = 200 Bq
ii) After 60 hours
60 Ă· 15 = 4 half-lives have passed:
400 Ă· 2 = 200 Bq after 1 half life (15hrs)
200 Ă· 2 = 100 Bq after 2 half lives (30hrs)
100Ă· 2 = 50 Bq after 3 half lives (45 hrs)
50Ă· 2 = 25 Bq
Answer
It would take 2 half lives for the count rate of the wood to be 25% of the initial count rate. (1 mark)
2 X 5600 = 11,200
So the sample of wood is 11,200 years old. (1 mark)
Sets 2 and 3: move on to task 12.
Task 8: Nuclear Radiation in Medicine - Set 1 only
Task 8c: Make notes that:
Explain what properties a radioactive source needs to have if it is being used inside the body.
Explain how radiation is used in the following medical devices:
(i) Radioactive tracers
(ii) Gamma cameras
(iii) Gamma radiation for destroying cancerous tumours
(iv) Radioactive implants
List the sources of background radiation and what % of the background count comes from each.
8d: Complete the exam question
Task 9: Nuclear Fission - Set 1 only
Task 9c: Make notes that:
Explain what happens during nuclear fission.
Draw and label a diagram (like diagram 1) showing nuclear fission.
Define chain reaction.
Explain how nuclear fission is used in a nuclear power station to generate electricity. Include a labelled diagram like diagram 2
Explain why control rods are needed in a nuclear reactor.
Define moderator and explain why it is needed in a nuclear reactor.
Explain why a nuclear reactor must be made of thick, high grade steel and why it must be encased in a thick concrete structure.
Task 10: Nuclear Fusion - Set 1 only
Task 10c: Complete the exam questions
Task 11: Nuclear Issues - Set 1 only
Task 11b: Make notes that:
Explain the factors that determine the effect that radiation has on living cells.
Write what the largest source of background radiation is.
Describe what happened at the Chernobyl and Fukushima nuclear power plants
Explain why these sites will remain dangerous for a very long time.
Give reasons why nuclear waste is a big issue.
Compare the risks and benefits of a nuclear fission power and nuclear fusion power.
Task 11c: Complete the exam question
Task 12: Summary
Task 12a: Watch the videos
Task 12b: Complete the Seneca learning for this unit
Task 12c: Make a mind map or single page revision summary of this topic and put it in your revision folder. Use the specification links and the example on the right to to help you.
Set 2 &3 - All of section 6.4 (pages 139 to 143)