1. A –Level Physics: Nuclear Decay Nuclear Fission and Fusion

2. Objectives:

3. FLASHBACK: Explain how standing waves are formed (6 marks)

4. Starter Activity Answer the following:
Describe the difference between a Hadron and a Lepton
What factors have to be conserved for a particle interaction to occur?
What is a cyclotron and how does it function?
What is a LINAC and how does it function?
What do the Lenz and Faraday law state?
Why would a magnet falling down a metal tube be slowed?
Name all the quarks and state how the top quark was predicted
If an electron is accelerated in a p.d. of 50V, how many joules were transferred to it?
If a magnetic field acts INTO the page, what direction would a positive particle spiral?
In a bubble chamber what would a gap in a path imply?
A muon is a lepton and as such is a fundamental particle (not made of anything smaller). Mesons are made up of smaller particles. 2) 23 hadrons, 23 baryons, 0 mesons, 11 leptons

5. Independent Study
Create a revision poster for the particle unit!

6. Nuclear Fission
In pairs, try to recap the process of nuclear fission and the structure of a nuclear reactor Use the following images to assist you!

7. Nuclear Fission- Uranium 235
Isotopes are elements that have the same proton number but different neutron number.
Many isotopes can be naturally fissile which means that when it absorbs a neutron, it splits into two daughter nuclei and releasing a huge amount of energy. The extra neutrons produced means that the reaction causes further ones to take place (chain reaction).
In this instance, as a neutron is introduced, the process is known as induced fission.
-400BC
antiquarks

8. Nuclear Fission- Binding Energy
The nucleus of an atom has a particular binding energy that is dependent on the nucleon number. It is the energy required to disassemble a whole nucleus into its constituent parts
-400BC
Sketch the graph below on a piece of graph paper. Make the line very clear as we will be annotating around the graph
antiquarks

9. Nuclear Fission- Binding Energy
The curve of binding energy (BE) per nucleon against mass number (nucleon number) has a peak at Iron-56.
The iron isotopes are the most closely bound and can be considered the boundary between elements that produce an energy yield from fusion (left of line) and those that do so from fission (right of line)
-400BC
antiquarks
ENERGY FROM FISSION
ENERGY FROM FUSION

10. Nuclear Fission- Binding Energy
Now, use this information to write the decay equation for Uranium 235. Don’t forget how the reaction is induced!
If you plot the following points on the graph, you will be able to identify the locations of Uranium 235 and its daughter nuclei, Barium-144 and Krypton-90
-400BC
1/0n + 235/92 U  144/56 Ba + 90/36 Kr + 2 x 1/0 n
Knowing this fission equation, draw a horizontal arrow from uranium over to the vertical position of krypton. Then finish by continuing your arrow upward to the Krypton coordinate.

11. Nuclear Fission- Calculating Fission Energy Release
There are four main steps:
Calculate the total mass of reactants
Calculate the total mass of products
Calculate the change in mass (∆m)
Use ∆E= ∆mc2
Worked Example: Estimate the total energy that could be released from 1kg of uranium-235 by a fission reaction yielding krypton-90 and Barium-144 and a single neutron. Assume that 1kg of uranium-235 contains 2.56x1024 atoms
DATA:
Mass of U= u
Mass of Kr= u
Mass of Ba= u
Mass of neutron= u
u is equivalent to 1.66x10-27kg
Guidance:
Calculate the change in mass
Convert to kg
Calculate energy change for an atom
Multiply by number of atoms present
See page 110 in orange rev. guide. Answer = MJ

12. Exam Question
Complete the exam practice provided. Use all your notes to help. I will assist you through the questions only once all are attempted and when you have marked your answers according to the mark scheme.
NOTES: show all your workings and pattern of thought, do not be vague
5.1 x N