Kinetic Molecular Theory

• Chemistry


  The study of matter
• Matter


  Anything that takes up space and has a mass
• States of matter


  • Solid
  • Liquid
  • Gas
• Matter


  • Made up of tiny particles
• Particles


  • There are spaces between them
  • There are attractive forces between them
  • They are in constant motion
• Changing state of matter

  1. Heating a solid increases kinetic energy of particles → vibrate more

  2. Particles have enough energy to pull away from each other and become liquid

  3. Further heating a liquid, further increases kinetic energy of particles until they have enough energy to escape attractive forces and become gaseous
• Kinetic energy (E_K)


  • When E_K is low, particles are closer together → stronger attractive forces between particles
  • When E_K is high, particles further apart → weaker attractive forces between particles
• Energy (E_P + E_K)

  • E_P: high, E_K: low
  • E_P: middle, E_K: middle
  • E_P: low, E_K: high
• Particles can exchange kinetic energy with one another when they collide
• Summary of states of matter

  • Solid: Particles in vibrational motion, E_P high, E_K low, fixed volume
  • Liquid: Particles in vibrational and rotational motion, E_P medium, E_K medium, non-fixed volume
  • Gas: Particles in vibrational and translational motion, E_P low, E_K high, non-fixed volume
• Propositions of the Kinetic Molecular Theory (KMT)

  • The absence of matter is a perfect vacuum
  • All matter is made up of tiny particles
  • The particles of any pure substance are identical to one another
  • There are spaces between particles
  • There are attractive forces between particles
  • Particles are in constant motion