Intermolecular forces

• What are intermolecular forces?

  Forces between molecules
• What is the difference between intermolecular forces and covalent bonds?

  Intermolecular forces attract molecules, covalent bonds connect atoms
• What is the first type of intermolecular force mentioned?

  Van der Waals forces
• How are van der Waals forces also known?

  London forces
• Why do electrons create a temporary dipole in an atom?

  Electrons are unevenly distributed around the atom
• What is a temporary dipole?

  A short-lived positive and negative end in a molecule
• How do temporary dipoles lead to molecular attraction?

  Positive and negative ends attract each other temporarily
• What type of dipole do some molecules have permanently?

  Permanent dipole
• How do permanent dipoles attract each other?

  Positive end attracts negative end of another molecule
• What is an example of a molecule with a permanent dipole?

  Hydrogen chloride (HCl)
• What is a hydrogen bond?

  A strong attraction between hydrogen and electronegative atoms
• Which atoms can form hydrogen bonds with hydrogen?

  Fluorine, oxygen, or nitrogen
• Why are hydrogen bonds important for water?

  They keep water liquid at room temperature
• How would water behave without hydrogen bonds?

  Water would be a gas at room temperature
• What is the strength comparison of different intermolecular forces?

  • Covalent bond: 100
  • Hydrogen bonds: 10
  • Permanent dipole-dipole: 5
  • Van der Waals forces: 1
• What are the three types of bonding between molecules?

  Van der Waals, dipole-dipole, hydrogen bonds
• How does the strength of intermolecular bonds compare to covalent bonds?

  Intermolecular bonds are weaker than covalent bonds
• What are intermolecular forces?

  Intermolecular forces are weak forces of attraction between molecules, distinct from the stronger covalent, ionic, or metallic bonds within substances.
• What are the three main types of intermolecular forces?

  London dispersion forces (induced dipole-dipole). Permanent dipole-dipole forces. Hydrogen bonding.
• What are the three main types of intermolecular forces?

  London dispersion forces (induced dipole-dipole). Permanent dipole-dipole forces. Hydrogen bonding.
• What causes London dispersion forces?

  They arise due to temporary fluctuations in electron distribution, creating instantaneous dipoles that induce dipoles in neighboring molecules.
• What type of molecules experience London dispersion forces?

  All molecules, but they are the only intermolecular forces in non-polar molecules.
• How does molecular size affect London dispersion forces?

  Larger molecules with more electrons have stronger London dispersion forces because they are more polarizable.
• What are permanent dipole-dipole forces?

  These are forces of attraction between polar molecules with permanent dipoles.
• Why do polar molecules experience permanent dipole-dipole forces?

  Polar molecules have regions of partial positive and partial negative charges that attract each other.
• Which type of molecules experience both London dispersion and permanent dipole-dipole forces?

  Polar molecules, as they have both instantaneous and permanent dipoles.
• What is hydrogen bonding?

  Hydrogen bonding is a strong type of dipole-dipole attraction between a hydrogen atom covalently bonded to , , or , and a lone pair on another , , or atom.
• Why is hydrogen bonding stronger than other intermolecular forces?

  The large electronegativity difference between hydrogen and , , or creates a highly polar bond, and the small size of the hydrogen atom allows close interaction.
• Give three examples of substances where hydrogen bonding occurs.


  Water , ammonia , and hydrogen fluoride .
• How do intermolecular forces affect boiling points?

  Stronger intermolecular forces require more energy to overcome, leading to higher boiling points.
• How do intermolecular forces affect boiling points?

  Stronger intermolecular forces require more energy to overcome, leading to higher boiling points.
• Why does water have a higher boiling point than methane ?

  Water has hydrogen bonding, which is much stronger than the London dispersion forces in methane.
• Why do non-polar molecules like oxygen have low boiling points?

  They only experience weak London dispersion forces.
• How do hydrogen bonds contribute to the properties of water?

  Hydrogen bonds give water a high boiling point, surface tension, and the ability to expand when frozen.
• What is the relationship between molecular shape and intermolecular forces?

  Molecules with larger surface areas or linear shapes have stronger London dispersion forces due to more extensive contact.
• How does electronegativity influence intermolecular forces?

  A greater difference in electronegativity between atoms in a molecule increases polarity, leading to stronger dipole-dipole forces or hydrogen bonds.
• Van der Waals forces

  A type of intermolecular force that arises from the interaction between non-polar molecules
• London forces


  A type of intermolecular force that arises from the induction of a temporary dipole in one molecule by the electronic cloud of another molecule, responsible for the attraction between two non-polar molecules
• Induction


  The temporary creation of a dipole moment in a molecule due to the presence of another charged molecule
• Electronic cloud


  The region around an atom or molecule where the electrons are free to move and are not localized to a specific orbit around the nucleus, characterized by a specific energy level