States of Matter-Intermolecular Forces and Kinetic Energy

This model represents the changes of state at the micro-particle level. In this model, the states of matter are determined by three factors--kinetic motion, attraction, and repulsion. By heating up and cooling down a set of particles, students can explore the fundamental features of three states. This model also allows students to explore the interplay between the attractive force and repulsive force. This model is particularly good for students to identify visual evidence for describing different states and the changes, as well as explore how intermolecular forces and kinetic energy influence the states of matter.

Grades: 6-8:
NGSS Standards: MS-PS1-4.

HOW IT WORKS

All the particles follow three rules: kinetic motion, attraction, and repulsion. The model starts with many randomly distributed particles. All particles have the same initial speed. When users "heat up" the particle, the speed increases. When users "cool down" the particle, the speed decreases. i.e., you add and remove kinetic energy.
Each particle is attracted to one of the other particles in a radius of 5, indicated by the fact that it moves towards the particle a little bit, determined by the slider "attractive-force." Each particle is repelled by one of the other particles if the distance between the two particles is less than 1, indicated by the fact that it moves away from the particle a little bit, determined by the slider "repulsive-force" if the distance is less than 1.

HOW TO USE IT

1. Choose "Number-of-particles" and "Particle-color" first. The colors do not indicate different types of particles. They are for fun.

2. Click on the button "start/reset" to confirm the setting, and then click "Run/Pause" to run the model.

3. Click the "heat up" or "cool down" buttons while running the model.

4. Use the sliders "attractive-force" and "repulsive-force" to adjust the levels of these two intermolecular forces.

THINGS TO NOTICE AND TRY

Can you identify the solid, liquid, and gas states in this model?
What evidence can you gather in the model for identifying each of the states?
Does the amount of matter change when the state changes?
What evidence can you gather in the model for determining whether the amount of matter changes?
What happens to the particles if there is no attractive force or repulsive force or neither? Can you still identify the three states now? Why?

CREDITS AND REFERENCES

This model is made by Dr. Lin Xiang at the University of Kentucky .If you mention this model in a publication, we ask that you include the citations below.

Xiang, L. (2020). States of Matter-intermolecular forces and kinetic energy. Department of STEM Education, University of Kentucky, Lexington, KY.

Questions? Comments? Email us.

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