HTML5 version.



  • Atomic Bonding
  • Chemistry
  • Dipole
  • Interaction Potential
  • Molecules


Watch different types of molecules form a solid, liquid, or gas. Add or remove heat and watch the phase change. Change the temperature or volume of a container and see a pressure-temperature diagram respond in real time. Relate the interaction potential to the forces between molecules.

Sample Learning Goals

  • Describe a molecular model for solids, liquids, and gases.
  • Extend this model to phase changes.
  • Describe how heating or cooling changes the behavior of the molecules.
  • Describe how changing the volume can affect temperature, pressure, and state.
  • Relate a pressure-temperature diagram to the behavior of molecules.
  • Interpret graphs of interatomic potential.
  • Describe how forces on atoms relate to the interaction potential.
  • Describe the physical meaning of the parameters in the Lennard-Jones potential, and how this relates to the molecule behavior.

For Teachers

need some CSI  worksheerts?




The new HTML5 sims can run on iPads and Chromebooks, as well as PC, Mac, and Linux systems.

iOS 12+ Safari
iPad compatible sims

Not officially supported. If you are using the HTML5 sims on Android, we recommend using the latest version of Google Chrome.

Latest version of Google Chrome
The HTML5 and Flash PhET sims are supported on all Chromebooks.
Chromebook compatible sims

Windows Systems:
Microsoft Edge and Internet Explorer 11, latest version of Firefox, latest version of Google Chrome.

Macintosh Systems:
macOS 10.9.5+, Safari 9+, latest version of Chrome.

Linux Systems:
Not officially supported. Please contact This email address is being protected from spambots. You need JavaScript enabled to view it. with troubleshooting issues.



Design TeamThird-party LibrariesThanks To
  • Yuen-ying Carpenter (lead designer, HTML5)
  • Amy Rouinfar (lead designer, HTML5)
  • Paul Beale (lead designer, Java)
  • Sarah McKagan (lead designer, Java)
  • Emily Moore (lead designer, Java)
  • Noah Podolefsky (lead designer, Java)
  • John Blanco (lead developer)
  • Aaron Davis (developer)
  • Aadish Gupta (developer)
  • Wendy Adams
  • Jack Barbera
  • Amy Hanson
  • Kelly Lancaster
  • Ariel Paul
  • Kathy Perkins
  • almond-0.2.9.js
  • base64-js-1.2.0.js
  • FileSaver-b8054a2.js
  • font-awesome-4.5.0
  • game-up-camera-1.0.0.js
  • he-1.1.1.js
  • himalaya-0.2.7.js
  • jama-1.0.2
  • jquery-2.1.0.js
  • lodash-4.17.4.js
  • pegjs-0.7.0.js
  • seedrandom-2.4.2.js
  • text-2.0.12.js
  • TextEncoderLite-3c9f6f0.js
  • Actual Concepts

Suggestor: Yuri

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