1. Radioactivity

2. Learning objectives:
To be able to recall and explain the structure and properties of the atom.
To be able to recall the three main types of radiation.
To be able to explain the structure and properties of the three main forms of radiation.

3. Can you name the parts of the atom?
Everything is made up of miniscule particles called ATOMS. Inside atoms are even smaller particles.
Can you name the parts of the atom?
This is the NUCLEUS.
ELECTRONS orbit the nucleus
PROTONS and NEUTRONS are found in the nucleus

4. PARTICLE
RELATIVE MASS
CHARGE
Proton 1 +
Neutron
Electron -
PARTICLE
RELATIVE MASS
CHARGE
There are usually equal numbers of Protons and Electrons in the atom. WHY?
This is because they carry opposite charges. If you have an equal number of + and – charges they will cancel each other out so we get a balanced or neutral atom.

5. Is this a stable (balanced) atom?
Why?
What is the MASS NUMBER?
5 (three Protons & two Neutrons)

6. 4 He 2 MASS NUMBER = number of protons + number of neutrons SYMBOL
ATOMIC NUMBER = number of protons

7. RADIOACTIVE MATERIALS
Most atoms are stable. However, radioactive atoms are not – they are unbalanced and unstable.
They ‘want’ to become stable (balanced). So to try to achieve this state they emit (give out) energy in the form of radiation.

8. This releases ENERGY. Sometimes a MASSIVE amount of energy.
Can you think of any examples?
We’ll look at examples and uses in more detail in another lesson.

9. What are they? TYPES OF RADIATION
How many types of radiation are there and how are they different?
What are they?

10. What do you notice?
So, what is an alpha particle?

11. ALPHA
Alpha particle
Unstable nucleus
New nucleus
Alpha () – an atom decays into a new atom and emits an alpha particle (2 protons and 2 neutrons)
Alpha radiation is the nucleus of a helium atom travelling at extremely high speed.

12. The Atomic number decreases by a value of 1.
What do you notice?

13. BETA
Beta particle
New nucleus
Unstable nucleus
Beta () – an atom decays into a new atom by changing a neutron into a proton and electron. The fast moving, high energy electron is called a beta particle.

14. The atomic structure doesn’t fundamentally change.
What do you notice?

15. GAMMA
Unstable nucleus
New nucleus
Gamma radiation
Gamma – after  or  decay surplus energy is sometimes emitted. The atom itself is not changed. Gamma radiation is part of the EM Spectrum; a wave with a very high frequency, very short wavelength.

16. Type of
radiation
Symbol
What is
it made
from?
How far
will it
travel in
air?
What
stops
it?

17. Types of radiation
Alpha () – a high speed helium nucleus is emitted (2 protons & 2 neutrons).
Unstable nucleus
New nucleus
Alpha particle
Beta () – the fast moving, high energy electron is called a beta particle.
Beta particle
Gamma (g) – after  or  decay surplus energy is sometimes emitted. Gamma radiation is a wave with very high frequency with short wavelength.
Unstable nucleus
New nucleus
Unstable nucleus
New nucleus
Gamma radiation

18.   g Type of radiation Symbol What is it made from? How far will it
travel in
air?
What
stops
it?
Alpha
  
Helium
nucleus. 2
protons &
2 neutrons
Beta
  
High speed
electron
Gamma
  g
High
energy
wave

19. Alpha, Beta and Gamma all have different properties:
They travel different distances
Different strengths
They are stopped by different
materials.
DEMO…

20. Radioactivity    Alpha, Beta, Gamma, Thick lead, Paper, Aluminium
Copy the diagram below and complete the arrows for each type. Then use the words at the bottom to construct an explanation in your own words.   
Alpha, Beta, Gamma, Thick lead, Paper, Aluminium

22.   g   g Type of radiation Symbol What is it made from? How far
will it
travel in
air?
What
stops
it?
Alpha
  
Helium
nucleus. 2
protons &
2 neutrons
 cm
Air /paper
Beta
  
High speed
electron m 
Aluminium
Gamma
  g
High
energy
wave
Lots of m 
Thick lead
&
concrete
Type of
radiation
Symbol
What is
it made
from?
How far
will it
travel in
air?
What
stops
it?
Alpha
  
Helium
nucleus. 2
protons &
2 neutrons
Beta
  
High speed
electron
Gamma
  g
High
energy
wave

23. Quiz
What do you call the centre of an atom?
Electron
Nucleus
Proton
Neutron

24. Quiz
2.A stable atom has…
Equal numbers of Protons & Electrons
Different numbers of Protons
Equal numbers of Electrons & Neutrons

25. Quiz
3.How many types of radiation are there? 3 9 2 4

26. Quiz
4.Radiation is emitted from…
All atoms
Most atoms
Unstable atoms
Stable atoms

27. Quiz
5.An alpha particle consists of…
2 protons
A high speed electron
A wave
2 protons and 2 neutrons

28. Quiz
6.Beta radiation is…
2 protons
A high speed electron
A wave
2 protons and 2 neutrons

29. Quiz
7.Gamma radiation is…
2 protons
A high speed electron
A wave
2 protons and 2 neutrons

30. Quiz
8.Alpha is stopped by…
Thick lead
Thin paper
A few cm of air
Aluminium

31. Quiz
9.Beta is stopped by…
Aluminium
Paper
Lead
Concrete

32. Quiz
10. Gamma is mostly stopped by…
A few cm of air
Thick lead
Aluminium
Paper

33. Can you recall and explain the structure and properties of the atom?
HAVE WE MET THE LEARNING OBJECTIVES?
Can you recall and explain the structure and properties of the atom?
Do you know the three main types of radiation?
Are you able to explain the structure and properties of the three main forms of radiation?

34. The End
Well Done!

35. Learning objectives:
To be able to recall and explain the structure and properties of the 3 forms of radiation.
To be able to explain the ionising properties of the 3 forms of radiation.
To be able to understand and explain the term ‘background radiation’ with examples.

36. IONIZING RADIATION
What does this mean?
When a charged particle comes near another atom, it can pull electrons off the atom.
This slows the particle down. The atom is then called an ion. If it has lost electrons, it is a positive ion.

37. Ionisation
When radiation collides with neutral atoms or molecules it alters their structure by knocking off electrons. This will leave behind IONS – this is called IONISING RADIATION.
 particle
Electron

38. So, what forms of radiation can be ionizing?
Only a charged particle such as an  or a  can be ionizing.
What about Gamma?
Gamma has no ionizing power. But it is still the most powerful radiation but passes through most objects.

39. A Neutron walks into a bar and asks the bartender ‘How much for a beer
The bar tender says…
‘For you sir, no charge’

40. BACKGROUND RADIATION
Radiation is always present in the environment. We call this ‘background radiation’. There are many sources of background radiation, these include:
Natural
Cosmic rays, Food, Rocks (particularly granite) & Radon gas.
Man-made
Hospitals, Nuclear bombs and testing, Nuclear power stations & accidents

41. Background Radiation 13% are man-made Radon gas Food Cosmic rays
Gamma rays
Medical
Nuclear power

43. Isotopes
An isotope is an atom with a different number of neutrons:
Notice that the mass number is different. How many neutrons does each isotope have? O 8 16 O 8 17 O 8 18
Each isotope has 8 protons – if it didn’t then it just wouldn’t be oxygen any more.
A “radioisotope” is simply an isotope that is radioactive – e.g. carbon 14, which is used in carbon dating.

44. The End
Well Done!

45. An atom bumps into a friend in the street and says ‘I’ve lost an electron’
The friend says ‘Are you sure’. The Atom says…
‘Yes, I’m positive’

46. Quick Quiz!
What does the term ionization mean?
What types of radiation cause ionization?
What is an isotope?
What is a radioisotope?

47. Quick Quiz!
What does the term ionization mean? When charged particles are produced – either gaining or removing electrons from particles.
What types of radiation cause ionization? Only Alpha and Beta.
What is an isotope? Atoms of the same element with a different Mass number (i.e. different numbers of neutrons).
What is a radioisotope? An isotope/s of an element which emits nuclear radiation

48. Learning objectives:
To appreciate that radiation can be harmful or beneficial.
To be able to explain how radiation can be used.
To be able to give examples of some of the common uses.

49. USES OF RADIATION
When we think of radiation, we think DANGER! Radiation is dangerous because it damages the DNA of living cells.
However, there are many ways which we can use radiation to our benefit.

50. How does radiation kill cancer cells?
What is the benefit of using radiation as opposed to an operation to remove a tumour?
Why does smoke inside the detector trigger the alarm?
Which type of radiation would be used to measure the thickness of a) Paper, b) Aluminium foil and C) Sheet steel?
Why sterilize plastic medical equipment with radiation?
How could a tracer be used to find a blockage in a kidney?

51. Have the LO been met?
To appreciate that radiation can be harmful or beneficial.
To be able to explain how radiation can be used.
To be able to give examples of some of the common uses.

52. The End
Well Done!