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Why Do Some Molecules Absorb Infrared Energy?

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:

Middle School

Disciplinary Core Ideas: 5

MS-PS1.A1:Substances are made from different types of atoms, which combine with one another in various ways. Atoms form molecules that range in size from two to thousands of atoms.

MS-PS1.A4:In a liquid, the molecules are constantly in contact with others; in a gas, they are widely spaced except when they happen to collide. In a solid, atoms are closely spaced and may vibrate in position but do not change relative locations.

MS-PS3.A4:The term “heat” as used in everyday language refers both to thermal energy (the motion of atoms or molecules within a substance) and the transfer of that thermal energy from one object to another. In science, heat is used only for this second meaning; it refers to the energy transferred due to the temperature difference between two objects.

MS-PS3.C1:When two objects interact, each one exerts a force on the other that can cause energy to be transferred to or from the object.

MS-PS4.B1:When light shines on an object, it is reflected, absorbed, or transmitted through the object, depending on the object’s material and the frequency (color) of the light.

Cross Cutting Concepts: 2

Structure and Function

MS-C6.1:Complex and microscopic structures and systems can be visualized, modeled, and used to describe how their function depends on the shapes, composition, and relationships among its parts; therefore, complex natural and designed structures/systems can be analyzed to determine how they function.

MS-C6.2:Structures can be designed to serve particular functions by taking into account properties of different materials, and how materials can be shaped and used.

Science and Engineering Practices: 4

Developing and Using Models, Constructing Explanations and Designing Solutions, Asking Questions and Defining Problems

MS-P1.2:ask questions to identify and/or clarify evidence and/or the premise(s) of an argument.

MS-P2.5:Develop and/or use a model to predict and/or describe phenomena.

MS-P2.6: Develop a model to describe unobservable mechanisms.

MS-P6.2:Construct an explanation using models or representations.

High School

Disciplinary Core Ideas: 1

HS-PS4.B2:When light or longer wavelength electromagnetic radiation is absorbed in matter, it is generally converted into thermal energy (heat). Shorter wavelength electromagnetic radiation (ultraviolet, X-rays, gamma rays) can ionize atoms and cause damage to living cells

Cross Cutting Concepts: 1

Structure and Function

HS-C6.2:The functions and properties of natural and designed objects and systems can be inferred from their overall structure, the way their components are shaped and used, and the molecular substructures of its various materials.

Science and Engineering Practices: 1

Developing and Using Models

HS-P2.6:Develop and/or use a model (including mathematical and computational) to generate data to support explanations, predict phenomena, analyze systems, and/or solve problems.

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