7.2. Nuclear Reactions
We learnt at GCSE that some isotopes of different elements are radioactive, Carbon-14, Uranium-235 etc. Why do some elements have halflives on the order of millions of years, whereas some decay withing milliseconds? We know that the nucleus is held together by the strong nuclear force, and the nucleon composition (numbers of protons and neutrons) of the nucleus determines the stability of these nuclei. This section looks a little bit into these ideas, and how we can calculate energy released through fission or fusion using Einstein's famous equation, E = mc².
Before we start, I love this video by Veritasium - trying to answer the question of 'What is the most radioactive place on Earth?'.
The section has been divided up as follows:
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Nuclear Stability - understanding which nuclei are stable or unstable
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Binding Energy and Mass Defect - how much energy is released through nuclear reactions?
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Fission and Fusion - Two key energy sources, but what's the difference?
Nuclear Stability
We already know some nuclei are stable and some are unstable. We also know that depending on the composition of the nucleus, the nucleus may decay through alpha, beta or gamma emission. Here we explore a little bit into these ideas. Crash Course have a nice little intro to get us started.
Video Lessons
Khan Academy | Nuclear Stability and Decay | |||||
Physics Online | Isotopes Intro |
Resources
IB Physics | Topic 7 Notes | |||||
IB-Physics.net | Chapter 7 Summary | IB Revision Notes | ||||
Mr. G | 7.2 Teaching Notes | 7.2 Student Notes | ||||
Physics and Maths Tutor | Particles Definitions | Particles Key Points | Particles Detailed Notes | Particles Flashcards | A Level Resources - content slightly different |
Questions
Cambridge University Press | Topic 7: Add Qs | Topic 7: Add Qs MS | Topic 7: MCQs | CUP Website Link | Freely available online | |
Grade Gorilla | 7.2 (Nuclear Equations) MCQ | Topic 7 (Nuclear) End Quiz | Quick IB Specific Mixed MCQs | |||
Mr. G | 7.2 Formative Assessment | Topic 7 Summary Qs | IB Specific Questions |
Binding Energy and Mass Defect
The key points of this section are explained quite nicely here:
This section is all about getting your head around the idea of a nuclear binding energy - the energy given out when a nucleus forms. Due to Einstein's famous equation, E=mc², this means that a bound nucleus of, for example, Helium (made of 2 protons, 2 neutrons) has a smaller mass than those same nucleons if they were free.
The reason this is idea of binding energy is significant is because it allows us to understand how we may produce energy from nuclear fusion (the fusing of smaller nuclei to form a larger nucleus) and nuclear fission (the splitting of a large nucleus to form daughter nuclei).
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It is important that we are able to understand the following plot, and the significance of Fe-56.
Heading 2
Fe-56 has the highest binding energy per nucleon.
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To the left of Fe-56, fusion is able to occur to release energy. To the right, fission will release energy.
Video Lessons
Chris Doner | Nuclear Binding Energy | IB Specific | ||||
Gradepod | Binding Energy per Nucleon | IB Specific | ||||
Khan Academy | Mass Defect/ Binding Energy | |||||
Science Shorts | Binding Energy | |||||
Study Nova | Binding Energy | Per Nucleon |
Resources
IB Physics | Topic 7 Notes | |||||
IB-Physics.net | Chapter 7 Summary | IB Revision Notes | ||||
Mr. G | 7.2 Teaching Notes | 7.2 Student Notes | ||||
Physics and Maths Tutor | Particles Definitions | Particles Key Points | Particles Detailed Notes | Particles Flashcards | A Level Resources - content slightly different |
Questions
Cambridge University Press | Topic 7: Add Qs | Topic 7: Add Qs MS | Topic 7: MCQs | CUP Website Link | Freely available online | |
Dr French's Eclecticon | Nuclear Physics | Nuclear Physics Solutions | Link to Dr French's Site | Extension: Pre-University Material | ||
Grade Gorilla | 7.2 (Nuclear Equations) MCQ | Topic 7 (Nuclear) End Quiz | Quick IB Specific Mixed MCQs | |||
Isaac Physics | Energy in Nuclear Reactions | |||||
Mr. G | 7.2 Formative Assessment | Topic 7 Summary Qs | IB Specific Questions |
Fission and Fusion
In this section, you should be able to link the above ideas of mass defect to calculate the energy produced through fission and fusion.
However, it is worth refreshing your memory on the key aspects of fission and fusion, so flick through the following resources.
PHET have a neat simulation looking at Uranium fission and the nuclear chain reaction.
PhD Comics have a nice YouTube video discussing fusion energy
Video Lessons
Chris Doner | Fission and Fusion | IB Specific | ||||
Science Shorts | Fission and Fusion |
Resources
IB Physics | Topic 7 Notes | |||||
IB-Physics.net | Chapter 7 Summary | IB Revision Notes | ||||
Mr. G | 7.2 Teaching Notes | 7.2 Student Notes | ||||
Physics and Maths Tutor | Particles Definitions | Particles Key Points | Particles Detailed Notes | Particles Flashcards | A Level Resources - content slightly different |
Questions
Cambridge University Press | Topic 7: Add Qs | Topic 7: Add Qs MS | Topic 7: MCQs | CUP Website Link | Freely available online | |
Dr French's Eclecticon | Nuclear Physics | Nuclear Physics Solutions | Link to Dr French's Site | Extension: Pre-University Material | ||
Grade Gorilla | 7.2 (Nuclear Equations) MCQ | Topic 7 (Nuclear) End Quiz | Quick IB Specific Mixed MCQs | |||
Mr. G | 7.2 Formative Assessment | Topic 7 Summary Qs | IB Specific Questions |
Additional Resources
IB Questions
A question by question breakdown of the IB papers by year is shown below to allow you to filter questions by topic. Hopefully you have access to many of these papers through your school system. If available, there may be some links to online sources of questions, though please be patient if the links are broken! (DrR: If you do find some broken links, please contact me through the site)
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Questions on this topic (Section 7) are shown in dark purple.
Use this grid to practice past IB questions topic by topic. You can see from the colours how similar the question topic breakdown is year by year. The more you can familiarise yourself with the IB question style the better - eventually you will come to spot those tricks and types of questions that reappear each year.