Intermolecular Force - Dipole–dipole Interactions

Dipole–dipole Interactions

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). An example of a dipole–dipole interaction can be seen in hydrogen chloride (HCl): the positive end of a polar molecule will attract the negative end of the other molecule and influence their arrangement. Polar molecules have a net attraction between them. For example HCl and chloroform (CHCl3)

Keesom interactions (named after Willem Hendrik Keesom) are attractive interactions of dipoles that are Boltzmann-averaged over different rotational orientations of the dipoles. The energy of a Keesom interaction depends on the inverse sixth power of the distance, unlike the interaction energy of two spatially fixed dipoles, which depends on the inverse third power of the distance.

Often molecules contain dipolar groups but have no overall dipole moment. This occurs if there is symmetry within the molecule that causes the dipoles to cancel each other out. This occurs in molecules such as tetrachloromethane. Note that the dipole–dipole interaction between two atoms is usually zero, because atoms rarely carry a permanent dipole. See atomic dipoles.

Read more about this topic:  Intermolecular Force

Other articles related to "interactions":

Molecular Attraction - Dipole–dipole Interactions
... 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) ... An example of a dipole–dipole interaction can be seen in hydrogen chloride (HCl) the positive end of a polar molecule will attract the negative end of the other molecule and influence their arrangement ...

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