AQA GCSE Physics 1b6 Radioactivity

1
AQA GCSE Physics 1b-6Radioactivity

• GCSE Physics pages 94 to 105

2
AQA GCSE Specification

• RADIOACTIVE DECAY
• 11.6 What are the uses and dangers of emissions
  from radioactive substances?
• Using skills, knowledge and understanding of how
  science works
• to evaluate the possible hazards associated
  with the use of different types of nuclear
  radiation
• to evaluate measures that can be taken to
  reduce exposure to nuclear radiations
• to evaluate the appropriateness of radioactive
  sources for particular uses, including as
  tracers, in terms of the type(s) of radiation
  emitted and their half-lives.
• Skills, knowledge and understanding of how
  science works set in the context of
• The basic structure of an atom is a small
  central nucleus composed of protons and neutrons
  surrounded by electrons.
• The atoms of an element always have the same
  number of protons, but have a different number of
  neutrons for each isotope.
• Some substances give out radiation from the
  nuclei of their atoms all the time, whatever is
  done to them. These substances are said to be
  radioactive.
• Identification of an alpha particle as a
  helium nucleus, a beta particle as an electron
  from the nucleus and gamma radiation as
  electromagnetic radiation.
• Properties of the alpha, beta and gamma
  radiations limited to their relative ionising
  power, their penetration through materials and
  their range in air.
• Alpha and beta radiations are deflected by
  both electric and magnetic fields but gamma
  radiation is not.
• The uses of and the dangers associated with
  each type of nuclear radiation.
• The half-life of a radioactive isotope is
  defined as the time it takes for the number of
  nuclei of the isotope in a sample to halve or the
  time it takes for the count rate from a sample
  containing the isotope to fall to half its
  initial level.

3
Observing nuclear radiationNotes questions from
pages 94 95

• (a) What is radioactivity? (b) How was it first
  discovered? (c) How is it detected nowadays?
• (a) How did Marie Curie advance our knowledge of
  radioactivity? (b) What did it cost her?
• List the three first types of radioactivity
  discovered and state how they differ from each
  other.
• (a) Why do some atoms decay? (b) Why is the word
  random used in the context of radioactivity?
• Copy and answer questions (a), (b) and (c) on
  pages 94 and 95.
• Copy the Key Points on page 95.
• Answer the summary questions on page 95.

4
Observing nuclear radiation ANSWERS

• In text questions
• No, the salts give out radiation all the time.
• Yes.
• Because it is emitted from the nucleus of an
  atom.

• Summary questions
• (a) Nucleus, protons and neutrons.
• (b) Nucleus, radiation.
• 2. (a) Alpha radiation.
• (b) Beta or gamma radiation.
• 3. Because they have an unstable nucleus that
  can become more stable by emitting radiation.

5
Alpha, beta and gamma radiation Notes questions
from pages 96 97

• Copy the table on page 96.
• Draw both Figures 2 and 3 on page 97 and describe
  how each of the three types of radiation is
  affected by magnetic and electric fields.
• (a) What is ionisation? (b) Why can ionisation be
  dangerous? (c) Compare the ionisation caused by
  the three types of radiation.
• Copy and answer questions (a), (b) and (c) on
  pages 96 and 97.
• Copy the Key Points on page 97.
• Answer the summary questions on page 97.

6
Alpha, beta and gamma radiation ANSWERS

• In text questions
• To stop the radiation, so it cant effect objects
  or people nearby.
• It is not deflected by a magnetic or an electric
  field.
• To keep the source out of range.

• Summary questions
• (a) Gamma
• (b) Alpha and beta, gamma.
• (a) Gamma (b) Alpha
• (c) Beta
• 3. Radiation can knock electrons from atoms.
  This ionisation damages the genes in a cell which
  can be passed on if the cell generates more cells.

7
Half-life Notes questions from pages 98 99

• What are isotopes?
• Copy both parts of Figure 1 on page 98.
• What is meant by count rate?
• Copy both ways of defining half-life found in
  bold type at the bottom of page 98.
• Copy Figure 2 on page 98 and explain how this
  type of graph can be used to find the half-life
  of an isotope.
• Copy and answer questions (a) and (b) on pages 98
  and 99.
• Copy the Key Points on page 99.
• Answer the summary questions on page 99.

8
Half-life ANSWERS

• In text questions
• 75 counts per minute
• 6.5 hours

• Summary questions
• 1. (a) Unstable, stable
• (b) Half-life, unstable
• 2. (a) 4 milligrams
• (b) 1 milligram

9
Radioactivity at workNotes questions from pages
100 101

• Copy Figure 1 on page 100 and explain how
  radioactivity is used in thickness control.
• Copy and answer questions (a) and (b) on page
  100.
• (a) Describe one way of using a radioactive
  tracer for medical treatment. (b) Why should such
  a tracer be a gamma emitter with a half-life of a
  few days. (c) What other properties should the
  tracer isotope have?
• Explain what is meant by (a) carbon and (b)
  uranium dating.
• Describe how a smoke alarm works.
• Copy and answer questions (c) and (d) on page
  101.
• Copy the Key Points on page 101.
• Answer the summary questions on page 101.

10
Radioactivity at work ANSWERS

• In text questions
• The detector reading increases and the pressure
  from the rollers is decreased.
• Alpha radiation would be stopped by the foil.
  Gamma radiation would pass through it without any
  absorption.
• B
• It was formed recently (in geological terms).

• Summary questions
• (a) Beta
• (b) Beta or gamma
• (c) Beta
• 2. (a) It needs to be detectable outside the
  body, non-toxic, have a short half-life (1 to 24
  hours) and decay into a stable product.
• (b) 11 200 years old.

11
Radioactivity issues Notes questions from pages
102 103

• Answer questions 1 and 2 on page 102.

12
Radioactivity issues ANSWERS

• 1. The alpha particles are very ionising and so
  cause a lot of damage to living cells. If they
  get into the lungs they will do a lot of harm.
  Our skin has a layer of dead cells that prevent
  the particle reaching living cells from the
  outside.
• 2. See page 97 figure 4.

13
How Science Works ANSWERS

• Scores can vary. Have you considered
  bias/impartiality/vested interests?
• Ethical Should people make decisions about other
  citizens that could affect their health?
• Social Lost jobs, poorer health services versus
  enviromental protection.
• Economic Are workers willing to take the
  increased risk or order to earn more money? Are
  people willing to pay more for their water to
  have it 100 safe?
• Enviromental Mining uranium increases
  radioactivity, but it is used to produce
  electricity in a way that does not increase
  global warming.