Students often use balanced nuclear reactions to model changes that occur in an unstable nucleus, but that doesn’t help students assess why the nucleus is unstable initially. In this activity, students use the band of stability and neutron-proton ratios to construct a simple predictive model to determine if an isotope will decay or not decay, and if the isotope does decay, whether the process is more likely to be alpha or beta decay. The activity does not address positron emission and gamma radiation.
Students calculate neutron-proton ratios for selected isotopes, determine if the isotope is stable or unstable, find the isotope’s location on the band of stability to determine decay type, and then write balanced nuclear equations for the isotopes that decay.
Nuclear medicine is a branch of medicine that relies on the proper selection of radioactive isotopes to produce scans like those above and to treat many types of cancer. Why do you think nuclear decay can be a powerful and useful medical tool? Discuss responses with your students. Some students may have personal experience with diagnostic tools or treatment.
HS-PS1-8. Develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the process of fission, fusion, and radioactive decay.
No PPE is required for the activity.
Copy the student pages or upload them to a class web page.
Construct a process diagram or flow chart that can be used to identify an isotope’s stability, and if unstable, how it will decay.
Your teacher will assign you a medical isotope. Use your model to determine if the isotope is stable or unstable, and if unstable, how it will decay. Write the balanced nuclear equation for the decay of the isotope.
Student answers will vary. Use the chart from the National Isotope Development Center (NIDC) to assign elements, and check to see that students follow their flow charts.
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