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The Nuclear Decay of Uranium Mark as Favorite (14 Favorites)

ACTIVITY in Alpha/Beta/Gamma Decay, Radioactive Isotopes, Graphing. Last updated May 12, 2023.

Summary

In this activity, students will model the Uranium decay series through nuclear equations, graphing, and particulate diagrams.

Grade Level

High School

NGSS Alignment

This activity will help prepare your students to meet the performance expectations in the following standards:

  • HS-PS1-8: Develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay.
  • Scientific and Engineering Practices:
    • Using Mathematics and Computational Thinking
    • Developing and Using Models
    • Analyzing and Interpreting Data

Objectives

By the end of this activity, students should be able to:

  • Describe the effect of beta and alpha decay on the nucleus through descriptions and particulate diagrams.
  • Interpret the meaning of  alpha decay and beta decay and demonstrate the change through writing a correct nuclear equation.
  • Plot data correctly to be displayed on a graph.
  • Explain the process that occurs during a decay chain for a radioactive isotope.

Chemistry Topics

This activity supports students’ understanding of:

  • Nuclear Chemistry
  • Alpha Decay
  • Beta Decay
  • Radioactive Isotopes
  • Balancing Nuclear Equations
  • Graphing

Time

Teacher Preparation: 10 minutes
Lesson: 45-60 minutes

Materials

  • Scissors
  • Pencil
  • Periodic Table
  • Student Handout

Safety

  • No specific safety precautions need to be observed for this activity.

Teacher Notes

  • Before completing this activity, students should understand nuclear symbols, atomic numbers, and mass numbers.
  • Students should know how to use an atomic number and a periodic table to determine the element (Ex: the atomic number 6 corresponds to carbon on the periodic table).
  • Check for understanding with the Background Reading Questions before starting the activity portion. It is important to confirm that students can write and balance nuclear equations before starting the activity.
  • When beginning the activity, it might be helpful for the teacher to explain the first nuclear equation shown on the handout to the students. This will ensure students know how to plot points on the graph, how to cut the atom, and how to balance the equation.
  • The teacher may decide to have the students use whiteout in the activity instead of scissors when “removing an alpha particle from the nucleus.” If scissors are used, the paper turned will be cut apart.
  • An Answer Key document has been provided for teacher reference.

For the Student

Purpose

Describe the effect of beta and alpha decay on the nucleus through descriptions, equations, graphs, and particulate diagrams.

Background

Uranium-238 is the most abundant isotope of uranium on earth and is found in most rocks, soil, and water. It is used to date rocks and ocean sediment older than 1 million years old. Using Uranium-238, scientists have determined the oldest rocks on Earth to be 4.4 billion years old.

Uranium-238 contains 92 protons and 146 neutrons and is an unstable nucleus. It is radioactive and undergoes alpha and beta decay, releasing energy. The nucleus of Uranium-238 transforms into different radioactive elements until it changes into a stable Lead-206 nucleus.

During alpha (𝜶) decay, a helium nucleus (42He), containing 2 protons and 2 neutrons, breaks off of the nucleus emitting energy. Alpha decay occurs when the nucleus has too many protons compared to neutrons. The resulting nucleus is a different element as it contains 2 fewer protons and neutrons. The total mass of the nucleus decreases.

During beta (𝜷) decay, a beta particle (0-1e) is emitted when there are too many neutrons in the nucleus compared to protons. A beta particle is a fast energetic electron. It is ejected from a nucleus along with an antineutrino when a neutron changes into a proton emitting energy. The resulting nucleus is a different element as there is one less neutron and one more proton in the nucleus. The total mass of the nucleus stays the same.

Uranium-238 goes through a 14-step decay process. One of the nuclei created during this process is radon. Radon is a colorless, odorless, radioactive gas that seeps up through the ground and can build up in basements. According to the EPA, Radon exposure is the number one cause of lung cancer among non-smokers.

In this activity, you will follow the process of Uranium-238 radioactively decaying until a stable nuclide with an ideal proton-to-neutron ratio is created. You will track how the nucleus changes through nuclear equations, graphing, and particulate diagrams.

Background Reading Questions

  1. Analyze the decay examples. What is the difference between a parent and daughter nuclide?
  1. Consider alpha decay:
    1. Describe in your own words how alpha decay works.
    1. What happens to the mass number and the atomic number during alpha decay?
  1. Consider beta decay:
    1. Describe in your own words how beta decay works.
    1. What happens to the mass number and the atomic number during beta decay?
  1. Analyze the mass numbers (top number, A) of both alpha and beta decay nuclear equations. Circle the true statement.
    1. The mass numbers of the products are always larger
    2. The mass numbers of the reactants are always larger
    3. The sum of the mass numbers on the reactant side always equals the sum of the mass numbers on the products side
  1. Analyze the atomic numbers (bottom number, Z) of both alpha and beta decay nuclear equations. Circle the true statement.
    1. The atomic numbers of the products are always larger
    2. The atomic numbers of the reactants are always larger
    3. The sum of the atomic numbers on the reactant side always equals the sum of the atomic numbers on the products side
  1. Use your answers to the previous 2 questions and a periodic table to complete the following nuclear equations. Justify your answers.

Uranium Decay Series Activity Instructions

For each step of the uranium decay series on the following page:

  1. Complete the nuclear equation by filling in the empty box with a nuclear symbol for the daughter nuclide. Remember that the sum of the mass numbers and the sum of the atomic numbers should be equal on both sides of the equation. Copy the daughter nuclear symbol produced in the current equation into the reactant box of the following equation representing the parent nuclide. The first one is done for you.
  2. Using the mass numbers and atomic numbers of the parent and daughter nuclides, graph each nuclide as a point on the mass number vs. atomic number graph. Connect the two points with a line. Label the line alpha or beta decay. The first one is done for you. The decay series ends when you plot a point on a stable point on the graph.
  3. On your uranium nucleus handout, change the nucleus as indicated by the type of decay. For alpha decay, cut off two protons and neutrons with scissors. For beta decay, shade in a neutron, making it a proton.

Conclusion Questions

  1. During the Uranium-238 decay series, Uranium changed into different elements. Eventually, Uranium-238 turned back into Uranium again.
    1. What other elements were created multiple times during the decay series?
    1. What is similar and different about the elements created multiple times?
  1. What step of the decay series is radon produced? Why is radon concerning? Hint: review the background information.
  1. What element ended the decay series? Why did it end with this element?