Organic Chemistry: Semester I › 1. Electrons, Bonds, and Structures

1.10 Physical Properties

Notes

1.10 Physical Properties

Sections

Physical Properties

Hydrogen bonds are dipole-dipole interactions that occur when a molecule with a hydrogen atoms bonded to an O or N is attracted to the lone pairs of an O or N on another molecule.

Classifications

  • H-bond acceptors have lone pairs that are available to accept a hydrogen from another molecule
  • H-bond donors have covalent bonds to hydrogens that are able to interact with electronegative atoms on another molecule

Determining the strength of intermolecular forces

  1. Identify all dipole-dipole interactions
  • If there are no dipole-dipole interactions, then the only intermolecular forces are London dispersion forces
  1. Identify all hydrogen bonding interactions
  • H bonds are a specific type of dipole-dipole interaction.
  1. Determine the number of carbons and the extent of branching
  • Generally, higher molecular weights and larger surface areas result in stronger intermolecular forces.