Intermolecular forces are forces of attraction or repulsion which act between neighboring particles (atoms, molecules or ions). They are weak compared to the intramolecular forces, the forces which keep a molecule together. There are a few types of attractive intermolecular forces such as: Dipole-Dipole Forces
Dipole–dipole interactions are electrostatic interactions of permanent dipoles in molecules. These interactions tend to align the molecules to increase the attraction (reducing potential energy). The positive end of a polar molecule will attract the negative end of the other molecule and influence their arrangement. Dipole-dipole forces have strengths that range from 5 kJ to 20 kJ per mole. They are much weaker than ionic or covalent bonds and have a significant effect only when the molecules involved are close together (touching or almost touching). London Dispersion
London dispersion forces are a type of force acting between atoms and molecules. It is caused by correlated movements of the electrons in interacting molecules. Electrons that belong to different molecules start "fleeing" and avoiding each other at the short intermolecular distances, which is frequently described as formation of "instantaneous dipoles" that attract each other. London forces are present between all chemical groups and usually represent the main part of the total interaction force in condensed matter, even though they are generally weaker than ionic bonds and hydrogen bonds. This is the only attractive intermolecular force present between neutral atoms, such as noble gases. Without London forces, there would be no attractive force between noble gas atoms, and they wouldn't exist in liquid form. Hydrogen Bonds
A hydrogen bond is the attraction between the lone pair of an electronegative atom and a hydrogen atom that is bonded to nitrogen, oxygen, or fluorine. The hydrogen bond is often described as a strong electrostatic dipole–dipole interaction....
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