Question

How do you recognize if a compound is London Force, Dipole-Dipole, and Hydrogen Bonding? Please provide examples

Answer 1

• If a compound is non-polar i.e., it has zero dipole moment, the only type of attractive intermolecular force present in the compound is London force. Examples- noble gases, methane, carbon dioxide, Cl2 etc.

Please note that a non-polar compound either has no polar bonds like noble gases, Cl2, H2 or the vector sum of dipole moments is zero as in CO2.

• If a molecule is polar i.e., it has permanent dipole moment, like HCl, SO2, CHCL3, the dominant intermolecular force present will be dipole-dipole forces.
• Now amongst polar molecules, those that have a H atom joined to a highly electronegative atom like F, O or N, will show Hydrogen bonding. Examples: H2O, NH3, HF etc.