Radioactive Isotopes

Part of an Access Excellence lesson
Modified for PULSE by Christopher Martin
Edited by Stephanie Nardei, MLS

Time: One class period
Materials: Internet access

Following the introductory lesson to Chernobyl, students will explore three different isotopes that were released into the atmosphere and contaminated numerous parts of Europe. In a written essay students attempt to sympathize with those affected by these radioactive contaminates. This lesson can be done alongside the math lessons to provide students with a fuller picture.

Students will be able to:
1. Describe an isotope and radioactive isotope in a written essay
2. Describe the health effects of the following:

  • Cesium 137,
  • Iodine 131 and
  • Strontium 90

3. Describe how a specific country or region was affected by radioactive contamination in a written essay

National Science Education Standard
CONTENT STANDARD C: Energy sources and Use
Nuclear reactions release energy without the combustion products of burning fuels, but the radioactivity of fuels and by-products poses other risks, which may last for thousands of years.

Strand 3: Science in Personal and Social Perspectives
Concept 1: Changes in Environments

Describe the interactions between human populations, natural hazards, and the environment.

Teacher Background
The most hazardous isotopes released in the Chernobyl incident were Cs-137, I-131, and Sr-90. These isotopes have half-lives sufficiently long to allow them to migrate into the human body or, in the case of Iodine, have the tendency to accumulate in the thyroid gland.

The plume from the burning graphite initially traveled in a northwest direction toward Sweden, Finland and Eastern Europe, exposing the public to levels up to 100 times the normal background radiation. A very serious concern involves the contamination of grain and dairy products from fallout. This contamination may cause permanent internal contamination. Both Sr-90 and I-131 migrate to vital organs in the body where they are impossible to remove, serving as a constant source of radiation and a cause of cancer or other diseases.

Related and Resource Websites
CDC Radioactive Isotopes http://www.bt.cdc.gov/radiation/isotopes
Global Radiation Patterns http://users.owt.com/smsrpm/Chernobyl/glbrad.html
Chernobyl 1 PULSE Lesson Plan http://pulse.pharmacy.arizona.edu/math/chernobyl1.html
PULSE Resource Page on Nuclear Radiation http://pulse.pharmacy.arizona.edu/resources/chemicals/students.htm


1. Ask students what caused the environmental health problems that resulted from the incident. Direct them towards the emission of radioactive isotopes.

2. What do they know about radioactive isotopes?

3. Explain there were three radioactive isotopes causing many of the problems. They are going to define what an isotope is, what makes it radioactive and some of the specific features of Cesium 137, Iodine 131, and Strontium 90. Please refer to: http://www.bt.cdc.gov/radiation/isotopes

4. Students then go to http://users.owt.com/smsrpm/Chernobyl/glbrad.html and look at the contamination of Iodine and Cesium radioactive isotopes in Europe.

5. Each student should imagine themselves in a European country on May 1st, 1986. Students should write an essay about Chernobyl including how they might feel and giving specific details about the contamination of their country.

Not Applicable.

Embedded Assessment
Students’ ability to describe what an isotope is, what a radioactive isotope is, the health effects of Cesium 137, Iodine 131 and Strontium 90 and how a specific country or region was affected by radioactive contamination can be assessed in a written essay.




PULSE is a project of the Community Outreach and Education Program of the Southwest Environmental Health Sciences Center and is funded by:

NIH/NCRR award #16260-01A1
The Community Outreach and Education Program is part of the Southwest Environmental Health Sciences Center: an NIEHS Award


Supported by NIEHS grant # ES06694

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