GENERAL CHEMISTRY 2

• Kinetic molecular model of liquids and solids

  • Explains the shape and volume of matter in the three states (gas, liquid, solid)
• Matter in gas state

  Indefinite shape and volume
• Matter in liquid state

  Indefinite shape, definite volume
• Matter in solid state

  Definite shape and volume
• Kinetic molecular theory (KMT) assumptions

  • Composed of molecules
  • Possess kinetic energy
• KMT assumptions mainly account for properties of gases
• Attractive forces between molecules

  Determine differences between gas, liquid and solid phases
• Liquids and solids have attractive forces between molecules, gases have negligible/no attraction
• Intermolecular forces


  Forces that hold molecules together
• Types of intermolecular forces

  • Dipole-dipole
  • Ion-dipole
  • Hydrogen bonding
  • London dispersion forces
• Van der Waals forces


  Collective term for intermolecular forces, result from attraction between opposite charges
• Van der Waals forces increase with increasing molecular weight
• Dipole-dipole forces


  Attraction between bond dipoles in different molecules
• Dipole-dipole forces


  • HCl
  • Water
• Ion-dipole forces


  Attraction between polar molecules and ions
• Ion-dipole forces


  • Sodium chloride dissolving in water
• London dispersion forces (LDF)


  Weak attractions between nonpolar molecules due to induced dipoles
• LDF increase with increasing molecular mass, decrease with increasing distance</b>
• Hydrogen bond


  Weak electrostatic attraction between partially positive hydrogen and negative group/lone pair

  
• Hydrogen bonds


  • Between molecules
  • Within molecules

  
• Intermolecular forces weaker than ionic/covalent bonds, but determine physical state and properties