Forces Acting Between Molecules

• What are intermolecular forces?


  Forces of attraction between molecules
• How do intermolecular forces compare to intramolecular forces?

  Intermolecular forces are weaker than intramolecular forces
• What physical properties do intermolecular forces affect?

  Boiling point, melting point, viscosity, surface tension
• What are dipole-dipole forces?

  Permanent forces between polar molecules
• What characterizes a polar molecule?

  It has a dipole moment due to charge separation
• How do dipole-dipole forces compare to Van Der Waals dispersion forces?

  Dipole-dipole forces are stronger than Van Der Waals dispersion forces
• What is hydrogen bonding?

  A special dipole-dipole force involving hydrogen and electronegative atoms
• Which atoms commonly participate in hydrogen bonding?

  Fluorine, oxygen, and nitrogen
• Why do molecules with hydrogen bonds have higher boiling points?

  Hydrogen bonds are stronger than other dipole-dipole forces
• How do van der Waals forces arise?

  From temporary fluctuations in electron distribution
• What type of molecules can experience van der Waals forces?

  All molecules, including nonpolar ones
• What induces dipoles in neighboring molecules during van der Waals forces?

  Temporary dipoles created by electron movement
• What factors affect the strength of van der Waals forces?

  Molecule size, shape, and surface area
• How does the size of a molecule influence van der Waals forces?

  Larger molecules have stronger van der Waals forces
• How does the shape of a molecule influence van der Waals forces?

  Linear molecules have stronger forces than branched ones
• What is a hydrogen bond?

  An intermolecular bond involving hydrogen and electronegative atoms
• What are the different types of intermolecular forces?

  Dipole-dipole forces, hydrogen bonding, and van der Waals forces
• How do dipole-dipole forces arise?

  Dipole-dipole forces arise between polar molecules due to the separation of positive and negative charge
• What is the relationship between dipole moment and the strength of dipole-dipole forces?

  Stronger dipole moments lead to stronger dipole-dipole forces
• What is hydrogen bonding and how does it arise?

  Hydrogen bonding is a special type of dipole-dipole force that occurs between molecules containing hydrogen bonded to a highly electronegative atom
• What are the three elements that can participate in hydrogen bonding?

  Fluorine, oxygen, and nitrogen
• Why do molecules with hydrogen bonds tend to have higher boiling points than similar molecules without hydrogen bonds?

  Because hydrogen bonds are stronger than other dipole-dipole forces, requiring more energy to overcome
• What is the basis for van der Waals forces?

  Van der Waals forces arise from temporary fluctuations in electron distribution within molecules
• How do the size and shape of molecules affect the strength of van der Waals forces?

  Larger molecules and linear molecules have stronger van der Waals forces due to greater surface area and more electrons
• What is the relationship between the number of electrons in a molecule and the strength of van der Waals forces?

  The greater the number of electrons, the stronger the van der Waals forces
• What are the steps of the scientific method?

  1. Ask a question
  2. Do background research
  3. Construct a hypothesis
  4. Test the hypothesis by doing an experiment
  5. Analyze the data and draw a conclusion
  6. Communicate the results