Molecular Geometry

• Intermolecular forces


  • Major factors that determine some properties of substances
• Stronger intermolecular forces

  Translates to greater surface area, higher melting and boiling point, greater viscosity, and lower vapor pressure
• Properties affected by intermolecular forces

  • Crystalline Formation
  • Vapor Pressure
  • Boiling and Melting Point
  • Surface Tension
  • Capillarity
  • Adhesion/Cohesion
  • Viscosity
  • Diffusion
  • Heat Capacity
  • Critical Point
• Crystalline formation


  Occurs when intermolecular forces create a regular structural pattern
• Vapor pressure


  Occurs due to the tendency of surface liquid particles to escape from the bulk liquid
• Boiling and melting point


  Conditions at which boiling occurs depend on the vapor pressure
• Surface tension


  Ability of liquids to form a shape with the smallest surface area
• Capillarity


  Tendency of liquids to rise or fall within a narrow tube
• Adhesion/Cohesion


  Attraction between like or unlike substances
• Viscosity


  A liquid's resistance to flow
• Diffusion


  Spreading out of fluid particles to occupy available space
• Heat capacity


  Heat required to raise the temperature of 1 g of a substance by 1°C
• Critical point


  Conditions in which the liquid and gaseous phases of a substance become indistinguishable
• Molecular structure is three-dimensional; thus, it is important to describe molecular bonds in terms of their distances, angles, and relative arrangements in space