Chem 2 Session 1

• Intermolecular forces

  Become weaker if the distance between molecules increases
• The kinetic molecular theory states that molecules interact with one another through attractive forces, and the strength of these forces is related to the distance between the particles
• Solids


  • Particles have strong intermolecular forces causing them to be very close together
  • Particle motion is restricted to vibrations
• The kinetic molecular theory of matter provides an overview of the microscopic properties of molecules or atoms and their interactions
• The kinetic molecular theory states that molecules are always in constant random motion
• Liquids


  • Particles have intermediate intermolecular forces causing them to be farther apart compared to solids
  • Particles can move about but in relatively short distances
• Temperature


  Is a measure of the average kinetic energy
• The kinetic molecular theory states that matter is composed of small particles
• The kinetic molecular theory states that the temperature of a substance is a measure of the average kinetic energy of the molecules
• States of Matter

  • Solid
  • Liquid
  • Gas
• Gases


  • Particles are very far apart due to weak intermolecular forces
  • Molecules are able to move in long distances
• States of Matter

  • solid: fixed shape, fixed volume, virtually incompressible
  • liquid: depends on the container, fixed volume, only slightly compressible
  • gas: depends on the container, assumes the volume of the container, very compressible
• How does the kinetic molecular theory explain phase changes?

  The physical state of matter is affected by both kinetic energy and intermolecular forces. At low temperatures, intermolecular forces dominate. At high temperatures, the molecules have higher kinetic energy and will be able to overcome the intermolecular forces present
• How can the kinetic molecular theory explain the properties of each state of matter?

  State of matter is determined by temperature and strength of intermolecular forces
• Kinetic Molecular Theory of Matter


  • Heat increases Kinetic Energy increases
• How does the kinetic molecular theory describe phases and phase changes?

  Intermolecular Force dictates the phase of matter. 2. Kinetic Energy helps particles to break free from Intermolecular Forces, thus, phase change
• The kinetic molecular theory states that: Matter is composed of small particles. The molecules interact with one another through attractive forces. The strength of these forces is related to the distance between the particles. These molecules are always in constant random motion. The temperature of a substance is a measure of the average kinetic energy of the molecules
• What happens in Melting?

  The molecules in ice vibrate back and forth to a specific location since it is in the solid phase. Increasing the temperature will provide enough kinetic energy to overcome their strong intermolecular forces. The solid becomes a liquid in a process called melting
• What happens in Vaporization?

  Particles between liquid water are slightly closer to one another. 2. Increasing its temperature will increase the kinetic energy of each water particle. 3. They then overcome the intermolecular forces that bind them together, freeing each particle, resulting in a gaseous phase
• Identify the state of matter being described below: The particles vibrate at a specific location only. The particles move about in relatively short distances. The particles move in longer distances
• States of Matter

  • solid (ice)
  • liquid (water)
  • gas (steam)
• As explained by KMT


  At lower temperatures, intermolecular forces determine the state of a substance. Substances with intermediate to strong intermolecular forces will form a condensed phase, either solid or liquid. Those with weak intermolecular forces will be in the gaseous state