1. Chapter 7.Nuclear Physics

2. What this covers? Inside the atom Discovery of the nucleus
Types of radiation
Nuclear reactions
Half life
Radioactivity in medicine
Nuclear Reactions – fission and fusion

3. INSIDE THE ATOM

4. What is the modern model of the atom?
The nucleus is where most of the mass of the atom is found. It contains protons and neutrons.
The electrons orbit the nucleus in layers called shells.
electron
neutron
proton
Charge
Mass
Particle 1 +1 1
almost 0 -1

5. Nuclear Notation
In the periodic table, there are two numbers found with each element. What do these numbers represent?
Mass number is the number of protons + the number of neutrons.
Atomic number (or proton number) is the number of protons

6. mass number is different atomic number is the same
Isotopes?
All carbon atoms have the same number of protons, but not all carbon atoms are identical.
Although atoms of the same element always have the same number of protons, they can have different numbers of neutrons. Atoms that differ in this way are called isotopes.
mass number is different
atomic number is the same
Isotopes tend to be unstable – these are the nuclei which are usually “radioactive”

7. Discovery of the nucleus

8. What was Rutherford’s involvement?
Teacher notes
This four-stage historical sequence explains Ernest Rutherford’s involvement in discovering the structure of the atom.

9. What did Geiger and Marsden do?
Teacher notes
This virtual experiment illustrates the experiment Geiger and Marsden used to get the results that led Rutherford to suggest his model of the atom. The components of the apparatus are broken down followed by the virtual experiment where the radiation detector can be moved to show the sort of results Geiger and Marsden would have got.

10. What were Geiger and Marsden’s results?
The results of Geiger and Marsden’s experiment were:
2. Some alpha particles were slightly deflected by the gold foil.
1. Most alpha particles
went straight through
the gold foil, without
any deflection.
3. A few alpha particles were deflected back from the gold foil.
The experiment was carried out in a vacuum, so deflection of the alpha particles must have been due to the gold foil.

11. How did Rutherford interpret the results?
Rutherford had expected all the alpha radiation to pass through the gold foil. He was surprised that some alpha particles were deflected slightly or bounced back.
The ‘plum pudding’ model could not explain these results, so Rutherford proposed his ‘nuclear’ model of the atom.
He suggested that an atom is mostly empty space with its positive charge and most of its mass in a tiny central nucleus.
Electrons orbited this nucleus at a distance, like planets around the Sun.

12. How did Rutherford explain the results?
Teacher notes
This four-stage animation shows how Geiger and Marsden’s experiment gave the results it did, and why Rutherford’s atomic structure model is supported by the results of the experiment.

13. Atomic structure – key words
Teacher notes
This matching activity could be used as a plenary or revision exercise on atomic structure. Students could be asked to complete the questions in their books and the activity could be concluded by the completion on the IWB.

14. Nuclear Radiation

15. What is alpha (α) radiation?
Boardworks GCSE Science: Physics
Radioactivity
2 neutrons, 2 protons
Description
Note:– An alpha particle is the same as a helium nucleus
Electric charge +2 4
Relative atomic mass
Stopped by paper or a few centimetres of air
Penetrating power
Ionizing effect
Strongly ionizing
Effect of magnetic/ electric field
Weakly deflected

16. What is beta (β) radiation?
Boardworks GCSE Science: Physics
Radioactivity
Description
High energy electron
Electric charge -1
Relative atomic mass
1/1860
Penetrating power
Stopped by a few millimetres of aluminium
Ionizing effect
Weakly ionizing
Effect of magnetic/ electric field
Strongly deflected

17. Boardworks GCSE Science: Physics Radioactivity
Gamma () radiation
Description
High energy electromagnetic radiation
Electric charge
Relative atomic mass
Penetrating power
Stopped by several centimetres of lead or several metres of concrete
Ionizing effect
Very weakly ionizing
Effect of magnetic/ electric field
Not deflected

18. 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.

19. Teacher notes
This true-or-false activity could be used as a plenary or revision exercise on the dangers of radiation, or at the start of the lesson to gauge students’ existing knowledge of the subject matter. Coloured traffic light cards (red = false, yellow = don’t know, green = true) could be used to make this a whole-class exercise.

20. Boardworks GCSE Science: Physics Radioactivity
Teacher notes
This matching activity could be used as a plenary exercise on the penetrating power of radiation. Students could be asked to complete the activity in their books or on mini-whiteboards. The activity could be concluded by completion on the IWB.

21. Boardworks GCSE Science: Physics Radioactivity
Teacher notes
This matching activity could be used as a plenary exercise on the range in air of the three types of radiation. Students could be asked to complete the activity in their books or on mini-whiteboards. The activity could be concluded by completion on the IWB.

22. Half Life

23. What happens to radioactivity?
Teacher notes
This five-stage animation explains why radioactivity decreases over time.

24. 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.

25. What is 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.
After 8 days = ½ remains
After 16 days = ¼ remains
After 24 days = 1/8 remains
And so on….

26. What is the half-life of carbon-14?
Teacher notes
This animated graph can be used as a real-life example of a decay curve, and how to work out half-life.
After the decay curve has animated, students could work individually or in small groups to calculate the half-life of carbon-14, and the activity could be concluded by completion on the IWB.

27. 141
60 hours

28. RADIOACTIVE DECAY

29. Types of radioactive decay

30. What happens during alpha decay?
An alpha particle consists of two protons and two neutrons. It is the same as a helium nucleus.
When an atom’s nucleus decays and releases an alpha particle, it loses two protons and two neutrons.
mass number decreases by 4
238 92
234 90 2 4  U Th + α
atomic number
decreases by 2
The number of protons has changed, so the decayed atom has changed into a new element.

31. What happens during beta decay?
An beta particle consists of a high energy electron, which is emitted by the nucleus of the decaying atom.
When an atom’s nucleus decays and releases a beta particle, a neutron turns into a proton, which stays in the nucleus, and a high energy electron, which is emitted.
mass number remains the same 14 6 7  C N + β
atomic number
increases by 1
The decayed atom has gained a proton and so has changed into a new element.

32. Radioactive decay – true or false?
Teacher notes
This true-or-false activity could be used as a plenary or revision exercise on radioactive decay, or at the start of the lesson to gauge students’ existing knowledge of the subject matter. Coloured traffic light cards (red = false, yellow = don’t know, green = true) could be used to make this a whole-class exercise.

33. Radioactivity at Work

34. Boardworks GCSE Science: Physics Radioactivity
Teacher notes
This drag and drop activity could be used as a plenary exercise to check students’ knowledge of everyday uses of radiation. Class voting or the use of coloured traffic light cards could make this a whole-class exercise.

35. Teacher notes
This true-or-false activity could be used as a plenary or revision exercise on everyday uses of radiation, or at the start of the lesson to gauge students’ existing knowledge of the subject matter. Coloured traffic light cards (red = false, yellow = don’t know, green = true) could be used to make this a whole-class exercise.

36. Nuclear Reactions

37. Fission
When fission of uranium-235 occurs, it splits into two smaller nuclei, known as daughter nuclei.
Many possible daughter nuclei may be formed in a fission process. One example is shown below. + 
neutron
uranium235
strontium90
xenon144
fission
neutrons
uranium
236
By the end of the lesson: State the products and reactants of fission reactions. Describe the processes using correct terminology. Apply your knowledge of the reactions to model them.

38. KE OF NUCLEI RISES RAPIDLY SO RAPID TEMPERATURE RISE
Chain Reaction
If the FAST neutrons produced in the reaction could be slowed down then they could be used to induce further fission in other U-235 atoms.
Graphite (CARBON) MODERATOR Collision with C atoms slows down the fast neutrons
KE OF NUCLEI RISES RAPIDLY SO RAPID TEMPERATURE RISE

39. Check point.
a. These neutrons go on to collide with other nuclei causing a chain reaction
b. The Uranium-235 nucleus splits
c. Energy is released
d. Neutrons are released
e. A neutron hits a Uranium-235 nucleus.

40. Nuclear fission – true or false?
Boardworks GCSE Additional Science: Physics
Nuclear Energy
Nuclear fission – true or false?
Teacher notes
This true-or-false activity could be used as a plenary or revision exercise on nuclear fission, or at the start of the lesson to gauge students’ existing knowledge of the subject matter. Coloured traffic light cards (red = false, yellow = don’t know, green = true) could be used to make this a whole-class exercise.
By the end of the lesson: State the products and reactants of fission reactions. Describe the processes using correct terminology. Apply your knowledge of the reactions to model them.

41. Nuclear Reactor Fission
Image from: courtesy of
Fission

42. Chain reactions – key words
Boardworks GCSE Additional Science: Physics
Nuclear Energy
Chain reactions – key words
Teacher notes
This matching activity could be used as a plenary or revision exercise on chain reactions. Students could be asked to complete the questions in their books and the activity could be concluded by the completion on the IWB.

43. Teacher notes
This two-stage animated sequence explains how nuclear fusion occurs in a fusion reactor.
By the end of the lesson: State what is meant by nuclear fusion. Describe the process and complete a nuclear equation for it. Identify the limitations with using fusion as an energy source and compare these with fission.

44. What are the conditions for nuclear fusion?
In nuclear fusion, small nuclei fuse together to form larger nuclei and energy is released. + 
tritium
deuterium
helium
neutron
fusion
Nuclear fusion happens all the time in stars at very high pressures and temperatures. These conditions overcome repulsive forces between the nuclei and force them together.
By the end of the lesson: State what is meant by nuclear fusion. Describe the process and complete a nuclear equation for it. Identify the limitations with using fusion as an energy source and compare these with fission.

45. Pros and cons of using nuclear fusion
Boardworks GCSE Additional Science: Physics
Nuclear Energy
Pros and cons of using nuclear fusion
Teacher notes
Appropriately coloured voting cards could be used with this classification activity to increase class participation.
By the end of the lesson: State what is meant by nuclear fusion. Describe the process and complete a nuclear equation for it. Identify the limitations with using fusion as an energy source and compare these with fission.