Types of Nuclear Decay

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Students will be able to explain why some atoms decay and differentiate between the three major types of decay (alpha, beta, and gamma) through taking notes and performing practice questions.

Big Idea

Unstable atoms can decay through alpha, beta, or gamma emission.


In this lesson students are introduced to the types of radioactive decay and how to balance nuclear reactions through notes and practice. 

  • This lesson covers the Next Generation Science and Engineering Performance Expectation 1-8: 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. It does so because students are being introduced to these ideas through a reading and videos.
  • This lesson aligns with the Next Generation Science and Engineering Practice 2: Developing and Using Models: It does so because students are using balanced nuclear reactions as a model to understand what happens in decay
  • For this lesson you need a laser pointer, ball, and four balloons tied together. 


40 minutes

I begin this lesson by leading students in notes. 

I present the notes from the PowerPoint while students take notes on their notes graphic organizer.

  • I start by talking about stable versus unstable isotopes on the first 3 slides of the notes.  
  • I then talk about radiation and the common sources of radiation on slide 4.
  • On slide 5 I discuss ionizing radiation.  When I talk about how it has enough energy to ionize matter I remind students what it is to be an ion.  This is a picture of what I draw when talking about this with students.
  • On slides 6 to 9 I talk about the three major types of radiation (alpha, beta, and gamma)
  • While teaching these types I make sure to help students differentiate between them.  I also show students how to balance nuclear reactions.  This video shows how I demonstrate balanced nuclear reactions for beta decay on slide 7.
  • I also give students a visual way to think about the types of decay.  I show them four balloons for alpha, a ball for beta, and a laser pointer for gamma.  This is a video of my explaining this to students.
  • Next, I go into the two additional types of beta decay- positron emission and electron capture on slides 10 and 11. 
  • I tell students about non-ionizing radiation on slide 12.
  • I finish the notes section by having students do example questions at the bottom of their notes that summarize the types of decay.  This is the answer key of what students should have for the answers for these questions.
  • This is a copy of a student's filled in notes.


30 minutes

To reinforce what we went over in the notes I have students practice balancing nuclear equations with the balancing nuclear practice questions worksheet.

I begin by passing out the paper.  

I then go over an example with the students for the first question of each of the three sections on the first page (1a, 2a, and 3a).  I then have students do the rest of the paper on their own.  I instruct them to get help from their partners if they are stuck and if their partner can't help them to then ask me for help as I walk around.

The biggest area of confusion for students is figuring out how to write out the balanced equations.  I instruct them to keep looking back at their notes for the examples and to use the patterns to help them.  Students also get confused with the differences between beta decay, electron capture, and positron emission.  I make sure to go over that in beta decay the symbol is on the product side; whereas in electron capture it is on the reactant side.  I also tell them how positron is the same symbol but it has a positive one, not negative.  

I have students complete the paper at home if they are not able to complete in class and I stamp for completion the next day.  I then go over the answers using the answer key paper.