Dipole-Dipole Interactions
Definition and meaning of Dipole-Dipole Interactions in chemistry.
Dipole-dipole interactions are electrostatic attractive forces that occur between neighboring polar molecules, where the partially positive end of one molecule is attracted to the partially negative end of another.
In more detail
These forces arise because polar molecules have a permanent dipole moment, created by uneven electron sharing between atoms of different electronegativity. Molecules tend to orient so opposite partial charges face each other, producing a net attraction that is weaker than ionic or covalent bonding but generally stronger than London dispersion forces alone in molecules of similar size. This is why polar substances often have higher boiling and melting points than nonpolar substances of comparable molar mass. Hydrogen bonding is considered an especially strong, specific case of dipole-dipole interaction.
Key facts
| Field | Physical Chemistry |
|---|---|
| Category | Intermolecular force |
| Requires | Molecules with a permanent dipole moment |
| Example compound | HCl |
In liquid hydrogen chloride (HCl), the partially positive hydrogen atom of one molecule is attracted to the partially negative chlorine atom of a neighboring molecule, an interaction that helps hold the liquid together.
Frequently asked questions
Are dipole-dipole interactions stronger than hydrogen bonds?
No. Hydrogen bonding is actually a stronger, specialized type of dipole-dipole interaction that occurs when hydrogen is bonded directly to a small, highly electronegative atom such as N, O, or F.
Do nonpolar molecules experience dipole-dipole interactions?
No, nonpolar molecules lack a permanent dipole moment, so they interact only through weaker, temporary London dispersion forces.