Dispersion Force Essay

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DISPERSION FORCE / LONDON FORCE The London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction. London forces are the attractive forces that cause nonpolar substances to condense to liquids and to freeze into solids when the temperature is lowered sufficiently. Because of the constant motion of the electrons, an atom or molecule can develop a temporary (instantaneous) dipole when its electrons are distributed unsymmetrically about the nucleus. A second atom or molecule, in turn, can be distorted by the appearance of the dipole in the first atom or molecule (because electrons repel one another) which leads to an electrostatic attraction between the two atoms or molecules. Dispersion forces are present between any two molecules (even polar molecules) when they are almost touching. INSTANTANEOUS DIPOLE – DIPOLE INTERACTION In dipole – dipole interactions, both of the molecules are uncharged yet polarized, meaning they are not ions with an extra or missing electron (anion or cation), rather, they are molecules with one end being more electropositive and another more electronegative. Such as HCl, when two HCl come close, they immediately configure in such a way as to have their opposite poles face each other. In instantaneous dipole – dipole interaction, the atom’s or molecules’ electrons are in spontaneous presence around the orbital causing flunctuations in their polarity structure. Once a dipole is spontaneously created, the incident will induce a polarity in another neighboring molecule. These forces are short of range and small
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