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Why Do Some Molecules Absorb Infrared Energy?
http://www.globalsystemsscience.org/studentbooks/cc/ch2/IRenergy

The Lawrence Hall of Science, The Lawrence Hall of Science

In this short, hands-on activity, students build simple molecular models of 4 atmospheric gases (O2, N2, C02, and methane), compare their resonant frequencies, and make the connection between resonant frequency and the gas's ability to absorb infrared radiation.

Activity takes about one to two 45-minute lesson periods.

Learn more about Teaching Climate Literacy and Energy Awareness»

ngssSee how this Activity supports the Next Generation Science Standards»
Middle School: 5 Disciplinary Core Ideas, 2 Cross Cutting Concepts, 4 Science and Engineering Practices
High School: 1 Disciplinary Core Idea, 1 Cross Cutting Concept, 1 Science and Engineering Practice

Notes From Our Reviewers The CLEAN collection is hand-picked and rigorously reviewed for scientific accuracy and classroom effectiveness. Read what our review team had to say about this resource below or learn more about how CLEAN reviews teaching materials
Teaching Tips | Science | Pedagogy | Technical Details

Teaching Tips

About the Science

  • The activity demonstrates how gas molecules in the atmosphere resonate when they are struck by vibrating photons of light energy. Molecular resonance is a key factor in the ability of greenhouse gases to absorb infrared energy.
  • Comments from expert scientist: Addresses a very common knowledge gap in understanding the greenhouse effect, what greenhouse gas molecules do, and which molecules are (and are not) greenhouse gases. The models highlight key structural differences between the non-greenhouse gases (N2 and O2) and the greenhouse gases (CO2 and CH4). It may be helpful to have a link to the “GSS Teacher Guide for Climate Change Chapter 2," which is mentioned as a resource.

About the Pedagogy

  • A hands-on activity for students to model how and why greenhouse gases absorb infrared energy and thus warm the atmosphere. Students build simple models of atmospheric gases and compare their resonant frequencies.
  • This activity is one of several in a chapter entitled "What's So Special About Carbon Dioxide", in the Climate Change section of the Global Systems Science online curriculum. Teacher Guides for this curriculum are available on a Teacher Site that is accessible by contacting the developer, Alan Gould, at http://www.globalsystemsscience.org/teacherguides.
  • A basic understanding of the electromagnetic spectrum, and where wavelengths of infrared and visible light energy fall on the spectrum, is useful.

Technical Details/Ease of Use

  • Activity is user-friendly with limited cost for reusable materials. Minimal preparation time required; educator is advised to pre-set the attachment points on the atoms (polystyrene balls) for the bonds (cable ties or pipe cleaners).
  • Many different kinds of materials can be used to create models of molecules, but not all of them will allow user to experiment with resonance.

Next Generation Science Standards See how this Activity supports:


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