Intermolecular forces

Intermolecular forces are forces of attraction or repulsion which act between neighboring particles (atoms, molecules, or ions). These forces are not to be confused with intramolecular forces, which exist within molecules.

Types of Intermolecular Forces

Intermolecular forces are categorized into several types:

Van der Waals forces

• London dispersion forces: These are weak intermolecular forces arising from the interaction of temporary electric dipoles that occur randomly in molecules.
• Dipole-dipole interactions: These occur when the positive end of a polar molecule attracts the negative end of another polar molecule.
• Hydrogen bonding: A strong type of dipole-dipole interaction that occurs when hydrogen is bonded to a highly electronegative atom such as oxygen, nitrogen, or fluorine.

Ionic bonding

Although primarily an intramolecular force, ionic bonds can also influence the properties of compounds through ionic interactions between molecules, especially in solutions.

Importance of Intermolecular Forces

Intermolecular forces are critical in determining the physical properties of substances, including boiling point, melting point, solubility, and viscosity. For example, hydrogen bonds give water its unique properties, which are essential for life.

Applications and Examples

Understanding intermolecular forces allows chemists to predict the behavior of substances in different conditions, manipulate chemical properties, and design new materials. For instance, the knowledge of these forces is crucial in the development of pharmaceuticals to ensure proper drug delivery within the body.

See Also

• Physical chemistry
• Thermodynamics
• Molecular physics