IB Physics HL E 3 15 Hl Neutron Proton Ratio Questions
Interpret HL neutron–proton ratios in stable nuclei by balancing strong-force attraction against long-range proton repulsion.
- Syllabus
- First assessment 2025
- Course
- Physics HL
- Level
- HL
Exam points
- interpret the stable-nuclide N–Z graph, including why high-Z stable nuclei require more neutrons than protons
- explain the different stability of calcium isotopes using nucleon number, neutron excess, strong-force attraction and Coulomb repulsion
- relate the short range of the strong force and long range of electrostatic repulsion to the neutron-to-proton ratio needed in heavy nuclei
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IB Physics HL E 3 15 Hl Neutron Proton Ratio Questions question 1
[Maximum number: 3]
This question is about nuclear reactions.
The daughter nuclei of U-235 undergo radioactive decay until eventually a stable isotope of lead is reached.
Explain why the nuclei of U-235 are unstable whereas the nuclei of the lead are stable.
protons repel/break nucleus apart;
binding energy/strong force holds nucleus together;
neutron excess / n:p ratio is greater in lead therefore overall balance of forces is more attractive / (magnitude of) binding energy per nucleon is greater in lead / binding energy per nucleon more negative in lead than uranium;
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