Greenhouse gases

The title of the Project: Greenhouse gases

This virtual laboratory is intended for use in chemistry classes on the following topics:

  • 8th grade. Chapter VI. “Greenhouse effect”.
  • 11th grade. Chapter XIV. “Green chemistry”.


  • Understand how light interacts with different molecules
  • Explore the concept of the greenhouse effect
  • Relate the energy of light to the motion of molecules
  • Connect light-molecule interactions to real-world phenomena

Practical part

This guide will show you how to use the PhET “Molecules and Light” virtual simulation to explore how different light particles (photons) interact with various molecules.

1. Setting Up the Simulation:

  • Find the light source selection buttons at the bottom of the screen. These buttons are arranged in order of increasing light energy, starting from microwave on the left to ultraviolet on the right.

  • On the right side of the screen, you’ll find a menu where you can choose from different molecules.

  • The center window will display the interaction between the chosen molecule and the light source.

2. Simulating Light Interaction:

  • Press the green button of the flashlight to turn on/off the light source. 
  • To analyze the interaction closely, you can pause the simulation using the pause button. You can then advance the simulation one frame at a time using the step forward button. This allows you to observe how the molecule absorbs a photon and re-emits it, rather than simply bouncing off.

3. Identifying Patterns:

  • As you explore different light sources and molecules, try to identify patterns in how the molecule interacts with each type of light.
  • For instance, infrared light can cause the molecule to vibrate. This helps you understand that the absorption of light and the resulting motion depend on both the molecule and the type of light used. (e.g., symmetric molecules don’t react to microwaves)

Table 1

 MicrowaveInfraredVisible LightUltraviolet

4. Analyzing Photon Energy and Molecular Motion:

  • You can investigate how the energy of the photon relates to the resulting motion of the molecule. Higher energy photons (like ultraviolet light) might cause the molecule to break apart (dissociate).

5. Resetting the Simulation:

  • If a molecule dissociates, you can bring it back by clicking the “Return Molecule” button. Alternatively, you can choose a different molecule from the menu on the right.

6. Real-World Connections:

  • This simulation can help you understand real-world phenomena. For example, you can see how certain atmospheric molecules, like carbon dioxide, act as greenhouse gases by absorbing specific types of light, while others, like oxygen, don’t.

7. Exploring the Light Spectrum:

  • The simulation includes a “Show Light Spectrum” menu. This menu displays information about the wavelengths and frequencies of different light types, reinforcing the concept that light energy increases from microwave to ultraviolet.


By using the PhET “Molecules and Light” simulation, students can experience an interactive learning to explore the interaction between light and different molecules. This helps them understand the scientific basis behind the greenhouse effect and its role in climate change.