D

Dipole-Dipole Interactions

ΔE = μ₁μ₂(1−3cos²θ)/(4πε₀r³); stronger with greater μ and smaller r
Quick Reference
Formula / NotationΔE = μ₁μ₂(1−3cos²θ)/(4πε₀r³); stronger with greater μ and smaller r
Also Known AsKeesom force (orientational), dipole-dipole force, polar intermolecular force

What is Dipole-Dipole Interactions?

Intermolecular attractive forces between polar molecules that arise from electrostatic interactions between permanent dipoles. The positive end of one molecule is attracted to the negative end of another. These forces are stronger than London dispersion forces but weaker than hydrogen bonds.

Formula & Notation

ΔE = μ₁μ₂(1−3cos²θ)/(4πε₀r³); stronger with greater μ and smaller r

Other Names / Synonyms: Keesom force (orientational), dipole-dipole force, polar intermolecular force

Properties & Characteristics

Dipole-dipole interactions are attractive forces between polar molecules in which the positive end of one molecule is attracted to the negative end of a neighbouring molecule. They are stronger than London dispersion forces for molecules of similar size. Energy falls off as 1/r³ for fixed orientations. In the liquid state, rotational averaging gives a 1/r⁶ dependence (Keesom interaction). The hydrogen bond is a special, strong case of dipole-dipole interaction.

Uses & Applications

Dipole-dipole forces explain the higher boiling points of polar molecules compared to nonpolar molecules of similar molecular weight. They govern the miscibility of polar solvents, the solubility of drugs in biological fluids, and the physical properties of liquid crystals.

Safety Information

Polar solvents with strong dipole-dipole interactions (acetone, DMF, DMSO) dissolve a wide range of chemicals and can enhance skin absorption of dissolved toxins. Handle solutions in polar solvents with appropriate PPE.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Dipole-Dipole Interactions
Formula ΔE = μ₁μ₂(1−3cos²θ)/(4πε₀r³); stronger with greater μ and smaller r
Synonyms Keesom force (orientational), dipole-dipole force, polar intermolecular force

Frequently Asked Questions

Intermolecular attractive forces between polar molecules that arise from electrostatic interactions between permanent dipoles. The positive end of one molecule is attracted to the negative end of another. These forces are stronger than London dispersion forces but weaker than hydrogen bonds.

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