Intermolecular Forces : London Dispersion Forces, Dipole Interactions, And Hydrogen Bonding

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Intermolecular forces have a great impact on many of the properties of a substance. There are three major types of intermolecular forces: London dispersion forces, dipole interactions, and hydrogen bonding. London dispersion forces are the weakest type of IMF and they occur in non-polar substances. They are the attraction and repulsion caused by the existence of momentary dipoles. These momentary dipoles occur because, although electrons are evenly dispersed on average in nonpolar molecules, at a certain instant, there may be an uneven distribution of electrons.2 The second type of IMF is the dipole-dipole interaction. This occurs when electrons are not shared equally in a covalently-bonded molecule. One section of the molecule has a partial positive charge and another section has a partial negative charge. Electrostatic attraction occurs between the partial negative charge of one atom and the partial positive charge of another molecule. Hydrogen bonding, the strongest IMF, is a specialized form of dipole-dipole interaction. This occurs when a hydrogen atom is bonded to an extremely electronegative atom, usually fluorine, oxygen, or nitrogen. The hydrogen atom has a partial positive charge and it is attracted to the partially negative F, N, or O of a neighboring atom.3
Melting point is closely related to intermolecular forces, as their energy must be overcome so that molecules can move around each other in a liquid form. In general, the stronger the IMFs that a…

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