Intermolecular Forces — Definition, Formula, Properties & Uses | AllChemicals | AllChemicals

Also Known As	Van der Waals forces (broad sense), intermolecular attractions, secondary forces

What is Intermolecular Forces?

Attractive and repulsive forces between molecules that determine physical properties like boiling point, viscosity, and surface tension. Types include London dispersion forces, dipole-dipole interactions, and hydrogen bonds. Stronger IMFs lead to higher boiling points and melting points.

Properties & Characteristics

Intermolecular forces (IMF) are the attractive or repulsive forces between molecules (as opposed to intramolecular forces which hold atoms together within a molecule). Types from weakest to strongest: London dispersion forces (temporary induced dipoles, in all molecules), dipole-dipole forces (between permanent dipoles), hydrogen bonds (N-H, O-H, or F-H bonded to N, O, or F), and ion-dipole forces (between ions and polar molecules). They determine physical properties (boiling point, solubility, viscosity, surface tension).

Uses & Applications

IMF understanding is applied in: predicting boiling points and miscibility, designing surfactants and emulsifiers, understanding protein folding and DNA base-pairing (hydrogen bonds), adhesive and lubricant formulation, chromatographic retention (stationary phase selection), and rational drug design (fitting drug molecules to protein binding pockets via multiple weak interactions).

Safety Information

No direct safety concern for the concept. Strong intermolecular forces (hydrogen bonds in HF, H₂O, concentrated H₂SO₄) contribute to high surface tension, viscosity, and reactivity. Hydrogen bonding in HF makes it anomalously dangerous — higher bp (19.5°C) and greater skin penetration than expected from a small molecule.

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

Key Facts

Term Intermolecular Forces

Index All "I" terms

Synonyms Van der Waals forces (broad sense), intermolecular attractions, secondary forces

Frequently Asked Questions

What is Intermolecular Forces?

Attractive and repulsive forces between molecules that determine physical properties like boiling point, viscosity, and surface tension. Types include London dispersion forces, dipole-dipole interactions, and hydrogen bonds. Stronger IMFs lead to higher boiling points and melting points.

What is Intermolecular Forces used for?

Is Intermolecular Forces hazardous?

More "I" Terms

Ideal Gas Ideal Gas Law PV = nRT | R = 8.314 J/(mol·K) Ideal Solution Ideal solution: Raoult's law holds; ΔH_mix = 0, ΔV_mix = 0 Ideal Solution Indicator Visual pH/endpoint indicator; e.g., phenolphthalein: colourless (acid) → pink (base) Indicators Indium In Induced Dipole Induced dipole: α × E (α = polarisability; E = electric field) Inert Gas Inert S Pair Effect Infrared Spectroscopy IR: 4000–400 cm⁻¹; C=O at ~1720 cm⁻¹ Inhibition Ki = [I]×Km / ([S](Vm/v − 1))

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