Particle Model & States of Matter

• Theory that explains the three states of matter

  Particle model of matter, or kinetic model of matter

  Also sometimes called particle theory or kinetic theory
• Particle (or kinetic) model of matter

  All matter consists of many very small particles that are constantly moving
• 3 assumptions of particle (or kinetic) theory

  Small

  Inelastic

  Spheres
• Use the particle (kinetic) model to explain how melting occurs

  In solids, strong attractive forces hold the particles in place, so they can only vibrate in position

  Substance is heated so particles gain energy and vibrate more quickly

  The particles have so much energy that they overcome the forces holding them together and the substance melts into a liquid
• Use the Particle (kinetic) model to explain how boiling occurs

  As heat is applied to a liquid, the particles gain kinetic energy and move faster

  With enough energy the forces of attraction between the molecules will break

  At this point the liquid boils into a gas
• What happens if a gas is heated in a fixed, closed container

  Pressure will increase as particles gain kinetic energy and move faster. This is because the container can’t expand so the volume is fixed
• Which state has the highest density

  Solid
• Use the particle model to explain condensation

  In gases the particles have enough energy to overcome the attractive forces so spread out randomly

  If the temp is lowered they will no longer have enough energy so the particles will move closer together and condense