IMF

• The design and interpretation of separation experiments (such as filtration, paper chromatography, column chromatography, or distillation) rely on the relative strengths of interactions between components. For example, components with weaker intermolecular forces will separate more easily than those with stronger forces.
• The strength of intermolecular forces affects various properties of substances:

  • Boiling/Melting Points: Stronger intermolecular forces result in higher boiling and melting points.
  • Surface Tension: Strong intermolecular forces lead to higher surface tension.
  • Viscosity: Substances with strong intermolecular forces tend to have higher viscosity.
  • Vapor Pressure: Strong intermolecular forces result in lower vapor pressure.
• The strength of London dispersion forces increases with:

  • Atomic size: Larger atoms have more electrons and can create larger instantaneous dipoles.

  Length of carbon chains: Longer carbon chains result in greater surface area and stronger dispersion forces.
• LDF = Nonpolar covalent molecules
• Instant dipoles occur due to the movement of electrons within a molecule, creating temporary regions of positive and negative charge. This can induce dipoles in neighboring molecules, leading to LDF
• 1. can identify the elements that will lead a molecule to have hydrogen bonding.

  FON + H
• 1. can compare and contrast dipole-dipole forces and hydrogen bonding.

  Dipole-Dipole Forces: Occur between polar molecules.

  Hydrogen Bonding: A specific, stronger type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative elements (N, O, F).
• Two factors that increase the strength of ion-dipole attraction are:

  • Charge of the ion: A higher charge leads to stronger attraction.
  • Polarity of the dipole: A more polar solvent increases the strength of the attraction.
• • Ion-Ion Attraction: Very strong due to full ionic charges; contributes to the high melting and boiling points of ionic compounds.
  • Ion-Dipole Attraction: Strong but generally weaker than ion-ion attraction; plays a crucial role in the solubility of ionic compounds in polar solvents.
• 1. can justify the strength of the dipole- dipole forces by the strength of the dipole present.

  The strength of dipole-dipole forces is related to the magnitude of the dipole moment present in the molecules. A larger dipole moment leads to stronger dipole-dipole attractions.
• 1. can explain whether a solution will form by comparing the strength of the attraction 

  A solution will form when the strength of the attraction between the solute and solvent molecules is greater than the attraction between the solute particles or solvent particles alone
• Molecules with dipole-dipole forces can be identified by their Lewis structure and polarity.

  If a molecule has polar bonds and an asymmetrical shape (also diff end elements), it will have a net dipole moment.
• 1.   can explain the intermolecular forces that exist in dipole-dipole attraction.

  Dipole-dipole forces occur between polar molecules that have permanent dipoles. The positive end of one dipole attracts the negative end of another dipole, leading to an attractive force.
• 1. ◦ can explain the difference between intramolecular and intermolecular forces.

  Intramolecular Forces: Forces that hold atoms together within a molecule (e.g., covalent bonds, ionic bonds).

  Intermolecular Forces: Forces that exist between molecules (e.g., hydrogen bonding, dipole-dipole interactions, London dispersion forces).

  Intra is stronger/greater than Inter
• • Shape:

  1. Solids: Have a fixed shape due to closely packed particles.
  2. Liquids: Take the shape of their container but have a definite volume.

  C. Gases: Have neither a fixed shape nor a definite volume; they expand to fill their container.
• • Volume:

  1. Solids: Have a definite volume.
  2. Liquids: Have a definite volume.

  c. Gases: Have an indefinite volume.
• • Compressibility:

  1. Solids: Not compressible.
  2. Liquids: Slightly compressible.

  C. Gases: Highly compressible.
• • Attraction:

  1. Solids: Strong intermolecular forces, resulting in a rigid structure.
  2. Liquids: Moderate intermolecular forces, allowing particles to slide past each other.
  3. Gases: Weaker intermolecular forces, resulting in free-moving particles.
• A solution will form when the strength of the attraction between the solute and solvent particles is greater than the attraction between the solute particles themselves and the solvent particles themselves
• In paper chromatography, the separation of components is primarily based on their polarity and their affinity for the stationary phase (the paper) versus the mobile phase (the solvent). Components that are more polar will interact more strongly with the paper and move more slowly, while less polar components will move faster with the solvent.
• Distillation separates components of a mixture based on their boiling points.