Unit 2-Particle Theory

Fluid Properties & The Particle Model (Theory)

The particle model helps to explain why gases and liquids flow, while solids do not.

- All substances are made of tiny particles

- All particles in a pure substance are the same (Different pure substances are made of different particles)

- All the particles have spaces between them

- All the particles are always in motion (the speed of the particles increases/decreases when the temperature increases/decreases)

- The particles in a substance are attracted to one another (the strength of the attraction depends on the type of particle)


-assumes the shape and volume of its container
-particles can move past one another

-lots of free space between particles
-flow easily past each other, move in all directions, do not flow to the lowest possible level


-takes the shape of the part of the container which it occupies
-particles can move/slide past one another
-not easily compressible
-little free space between particles
-can be poured (always flowing to the lowest possible level) and form a level (flat) surface at rest


-retains a fixed volume and shape

-rigid-particles vibrating in place

-not easily compressible

-little free space between particles

-form a pile when they are poured (the particles do not continue to flow apart from each other)


Click in corner to make bigger

Watch all videos and answer the questions

Click in corner to make bigger

Watch all videos and answer the questions

Click in corner to make bigger

Watch all videos and answer the questions

Videos for Clarification

Chapter 7 Review

Science Max-Solids, Liquies and Gases

Mass, Volume and Density

Chapter 7

Chapter 7 Questions Review



Chapter 8

Chapter 8 Review Questions

Chapter 8 Review Sheet


Chapter 9

Chapter 9 Review Questions



Crushing can Experiment

What caused the can to collapse?

When you heated the can you caused the water in it to boil. The vapor from the boiling water pushed air out of the can. When the can was filled with water vapor, you cooled it suddenly by inverting it in water. Cooling the can caused the water vapor in the can to condense, creating a partial vacuum. The extremely low pressure of the partial vacuum inside the can made it possible for the pressure of the air outside the can to crush it.

A can is crushed when the pressure outside is greater than the pressure inside, and the pressure difference is greater than the can is able to withstand. You can crush an open aluminum can with your hand. When you squeeze on the can, the pressure outside becomes greater than the pressure inside. If you squeeze hard enough the can collapses. Usually, the air pressure inside an open can is the same as the pressure outside. However, in this experiment, the air was driven out of the can and replaced by water vapor. When the water vapor condensed, the pressure inside the can became much less than the air pressure outside. Then the air outside crushed the can.

When the water vapor inside the can condensed, the can was empty. You may have expected the water in the pan to fill the can through the hole in the can. Some water from the pan may do this. However, the water cannot flow into the can fast enough to fill the can before the air outside crushes it.