Intermolecular forces

• What can cause an uneven distribution in molecules?

  Random movement of electrons
• What is the result of an uneven distribution in molecules?

  It results in a temporary dipole
• What can induce a temporary dipole in a nearby molecule?

  A temporary dipole in another molecule
• What is the term for the weak attraction caused by temporary dipoles?

  London forces
• How does the number of electrons in a molecule affect London forces?

  More electrons increase the strength of London forces
• What happens to the London forces as the size of the molecule increases?

  London forces become stronger
• What type of intermolecular force is a hydrogen bond?

  A strong type of dipole-dipole interaction
• What is required for a hydrogen bond to form?

  A hydrogen atom bonded to an electronegative atom
• Which atoms can form hydrogen bonds?

  N, O, and F
• How do hydrogen bonds affect the structure of ice compared to liquid water?

  Ice has a more ordered structure than liquid water
• What are polar molecules?

  Molecules with a net dipole moment
• What causes a molecule to be polar?

  Unequal sharing of electrons between atoms
• How do polar molecules interact with nonpolar molecules?

  They do not interact significantly
• What are the characteristics of hydrogen bonds?

  • Stronger than London forces
  • Weaker than covalent bonds
  • Formed between hydrogen and electronegative atoms (N, O, F)
  • Important in biological molecules (e.g., DNA, proteins)
• What are the differences between intermolecular forces?

  • London forces: Weak, temporary dipoles
  • Dipole-dipole interactions: Between polar molecules
  • Hydrogen bonds: Strong dipole-dipole interactions involving H
• What is the role of intermolecular forces in physical properties?

  • Determine boiling and melting points
  • Influence solubility and vapor pressure
  • Affect viscosity and surface tension
• How do molecular size and shape affect intermolecular forces?

  • Larger molecules have stronger London forces
  • Shape affects how closely molecules can pack
  • More surface area increases interaction strength
• What is the significance of dipole moments in molecules?

  • Measure of polarity
  • Affect molecular interactions
  • Influence physical properties like boiling point
• How do intermolecular forces affect the behavior of liquids?

  • Determine viscosity and surface tension
  • Influence evaporation rates
  • Affect capillary action and boiling points
• What happens to the molecular electron negativity when the ends of a molecule change?

  The ends of the molecule become more attracted.
• What is the weak attractive force called that is formed between molecules?

  It is called a permanent dipole-dipole interaction.
• What type of atoms can form hydrogen bonds?

  Only electronegative hydrogen atoms can form them.
• What is the relationship between the electronegativities of carbon and hydrogen?

  They are similar in electronegativity.
• What should be shown when drawing diagrams of hydrogen bonds?

  Show the dipole changes on relevant atoms.
• What is the bond angle of the O-H bond?

  It should be 180°.
• What are the key points about hydrogen bonds in molecules?


  • Formed between electronegative atoms
  • Weak attractive forces
  • Important in molecular interactions
  • Do not form between hydrogen and carbon