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The attractive force draws molecules closer together and gives a real gas a tendency to occupy a smaller volume than an ideal gas. Which interaction is more important depends on temperature and pressure (see compressibility factor). In a gas, the distances between molecules are generally large, so intermolecular forces have only a small effect.
Van der Waals forces include attraction and repulsions between atoms, molecules, as well as other intermolecular forces.They differ from covalent and ionic bonding in that they are caused by correlations in the fluctuating polarizations of nearby particles (a consequence of quantum dynamics [6]).
Therefore, at low temperatures, and low pressures, attraction is the dominant intermolecular interaction. If two molecules are moving at high speeds, in arbitrary directions, along non-intersecting paths, then they will not spend enough time in proximity to be affected by the attractive London-dispersion force.
The ideal gas model tends to fail at lower temperatures or higher pressures, when intermolecular forces and molecular size becomes important. It also fails for most heavy gases, such as many refrigerants, [2] and for gases with strong intermolecular forces, notably water vapor. At high pressures, the volume of a real gas is often considerably ...
The intermolecular force was later conveniently described by the negative derivative of a pair potential function. For spherically symmetric particles, this is most simply a function of separation distance with a single characteristic length, σ {\displaystyle \sigma } , and a minimum energy, − ε {\displaystyle -\varepsilon } (with ...
London dispersion forces (LDF, also known as dispersion forces, London forces, instantaneous dipole–induced dipole forces, fluctuating induced dipole bonds [1] or loosely as van der Waals forces) are a type of intermolecular force acting between atoms and molecules that are normally electrically symmetric; that is, the electrons are ...
In condensed matter physics and physical chemistry, the Lifshitz theory of van der Waals forces, sometimes called the macroscopic theory of van der Waals forces, is a method proposed by Evgeny Mikhailovich Lifshitz in 1954 for treating van der Waals forces between bodies which does not assume pairwise additivity of the individual intermolecular forces; that is to say, the theory takes into ...
A depletion force is an effective attractive force that arises between large colloidal particles that are ... If the intermolecular potentials also include repulsive ...