Notes
The following notes are from 'The National Science and Math Initiative' site. (Sounds very fancy, but obviously American) The link is as follows, but integrated beside the links are videos that may help you understand the topics a little better.
http://ap-physics.alhs.dps.schoolfusion.us/modules/locker/files/get_group_file.phtml?gid=1418448&fid=7647060
Fluids at Rest
What you already know:
• Fluids–matter that flows such as gases or liquids
Phases or States of Matter
Solids–molecules are very close together [due to strong intermolecular forces] with no
translational or rotational motion, only vibration about fixed points. This means they are not very compressible and have a fixed shape, size, and volume.
Liquids–molecules have all three types of motion and are close together [still due to strong intermolecular forces], but can slide past one another [which is why they flow and have no fixed shape!]. They are still not very compressible and have a fixed volume but take on the shape of the container, yet may not fill the container.
Gases–molecules have all three types of motion, are very energetic and have overcome all intermolecular forces and are 2,000 molecular diameters farther apart than in either the solid or liquid phase where they are usually less than one molecular diameter apart. Gases expand to fill their container since there are no intermolecular forces acting to keep them attracted to one another. They are very compressible, have no fixed size, shape, or volume
Plasma–exist only at very high temperatures and consists of ionized atoms
Colloids–a suspension of solid particles in a liquid- some argue that this should be a separate state of matter, others consider it a liquid.
If the particles in a mixture with a liquid solvent are too small to refract light, we call it a solution.
If the particles are too large, you can’t keep them in solution [so they don’t hang around long enough to refract light] and they settle, we call that a suspension.
A colloid is in between with regard to particle size and does refract light [Tyndall effect]. Milk is a colloid of fat particles suspended in a water and lactose solution. If you add chocolate syrup and stir you can make a suspension–the chocolate particles settle but the fat particles remain in solution!