Unit 1: Physical Properties of Matter Lesson 2

 1) All matter is made up of tiny particles.  2) All particles of one substance are the same. Different substances are made up of different particles.

 3) The particles are always moving. The more energy that the particles have, the faster they move.  Kinetic Energy is defined as the energy a body possesses due to its motion. (KE=1/2mv 2, where v=velocity )  Average kinetic energy is easily measured as temperature

 4) There are attractive forces between particles. These forces are stronger when the particles are closer together. matter matter

The Kinetic Molecular Theory (KMT) adds to our understanding of “particles”. Postulates of KMT: 1. All matter (solid, liquid, and gas) is made up of tiny particles called atoms, or atoms that are joined to form molecules. 2. These particles are in constant motion. (Look familiar?? It should.)

3. Molecular motion is random. culartheory/Diffusion.html

3. Particles in motion possess kinetic energy. 4. Their motion increase as they gain energy There is an exchange (transfer) of energy between particles (atoms and molecules) during a collision between them.

6. Particles (molecules) in gases do not exert large forces on each other, unless they are in collision with each other. 7. Collisions between these particles are perfectly elastic.

8. Molecular motion is greatest in gases, less in liquids, and least in solids. 9. Solids retain a fixed volume and shape (not compressible) - particles are tightly packed, usually in a regular pattern.

10. Liquids assume the shape of the container which it occupies but maintain their volume (not compressible) - particles close together with no regular arrangement.

11. Gases assumes the shape and volume of its container and will expand to fill a container of any size (compressible) - particles are very far apart with no regular arrangement.

 The kinetic molecular theory is very useful in:  explaining or describing the forces between molecules and the energy that they possess  explaining the effects of thermal energy, temperature and pressure on matter.