Kinetic Molecular Theory of Matter

• Kinetic Molecular Theory of Matter

  • provides an overview of the microscopic properties of molecules or atoms and their interactions
  • describes the microscopic properties of matter and how they translate to the the state and other properties of matter
  • states that matter is composed of small particles
  • states that the molecules interact with one another through attractive forces. Strength of these forces related to the distance
  • states that these molecules are are always in constant random motion
  • states that the temperature of a substance is a measure of the average kinetic energy of the molecules
• Intramolecular Forces - the attractive forces within molecules
• Intermolecular Forces - the attractive forces between molecules
• Main Types of Intermolecular Forces

  • Ion-Ion Interaction
  • Ion-Dipole Interaction
  • Dipole-Dipole Interaction
  • Hydrogen Bonding
  • London Dispersion Forces
• Ion-Ion Interaction

  Interaction between two oppositely charged particles (e.g. NaCl) - also known as ionic bonds - between electrically charged particles
• Ion-Dipole Interaction

  The partially positive end of the polar molecular interacts with the anion, whereas the partially negative end of the polar molecule interacts with the cation (e.g. Brine - NaCl in water)
• Dipole-Dipole Interaction

  Interaction between positive end and negative end of the two molecules
• Hydrogen Bonding

  Hydrogen bonded to Fluorine, Oxygen, Nitrogen - strong bonding because F, O, N are atoms with high electronegativity value
• London Dispersion Forces

  Occurs in nonpolar/equal sharing of electrons (e.g. H2 H - H, Br2 Br - Br) - no partially positive end because it's equal
• Dipole-Dipole Interaction:

  • dipoles - present in polar molecules
  • occurs between partially negative and partially positive end
  • HCl has Intramolecular Forces because it's within molecules
  • Electronegativity - tendency of an atom to attract electrons so hydrogen is attracted to Chlorine
  • Hydrogen - 2.1 electronegativity
  • Chlorine - 3.0 electronegativity
  • Therefore, chlorine is like a magnet as it will become partially negative (δ-) and partially positive (δ+)
  • Then, intermolecular forces come to play when two HCl combine

  
• Hydrogen Bonding:

  • Also exhibit dipole-dipole because of interaction of positive and negative

  A) dipole-dipole

  B) Hydrogen

  
•  dipole moment -  is the product of the magnitude of the charge and the distance between the centers of the positive and negative charges

  
• NonPolar (London Dispersion Forces) - 0 - 0.4

  Polar (Dipole-Dipole) - 0.5 - 1.7

  Ionic (Ion-Ion) - 1.7 - infinity