Search results
Results From The WOW.Com Content Network
The authoritative work [13] contains a criticism of the instantaneous dipole model [14] and a modern and thorough exposition of the theory of intermolecular forces. The London theory has much similarity to the quantum mechanical theory of light dispersion, which is why London coined the phrase "dispersion effect". In physics, the term ...
The third and dominant contribution is the dispersion or London force (fluctuating dipole–induced dipole), which arises due to the non-zero instantaneous dipole moments of all atoms and molecules. Such polarization can be induced either by a polar molecule or by the repulsion of negatively charged electron clouds in non-polar molecules.
Dispersion forces keep the molecule inert even while its core Si-Si bond lengthens. Similarly, the longest known Ge-Ge bond is found in t Bu 3 GeGe t Bu 3 and is also facilitated by dispersion stabilization. [19] Dispersion stabilization has also been invoked for (t BuC) 3 P, a main group analog of a hydrocarbon tetrahedrane. [20]
The source of adhesive forces, according to the dispersive adhesion mechanism, is the weak interactions that occur between molecules close together. [2] These interactions include London dispersion forces, Keesom forces, Debye forces and hydrogen bonds. Individually, these attractions are not very strong, but when summed over the bulk of a ...
The van der Waals force between two molecules, in this context, is the sum of the attractive or repulsive forces between them; these forces are primarily electrostatic in nature, and in their simplest form might consist of a force between two charges, two dipoles, or between a charge and a dipole. Thus, the strength of the force may often ...
London dispersion forces are also known as 'dispersion forces', 'London forces', or 'instantaneous dipole–induced dipole forces'. The strength of London dispersion forces is proportional to the polarizability of the molecule, which in turn depends on the total number of electrons and the area over which they are spread.
The Fowkes hypothesis (after F. M. Fowkes) is a first order approximation for surface energy.It states the surface energy is the sum of each component's forces: γ=γ d +γ p +γ i +... where γ d is the dispersion component, γ p is the polar, γ i is the dipole and so on.
Van der Waals forces originate from the interactions between induced, permanent or transient electric dipoles. In comparison with chemisorption , in which the electronic structure of bonding atoms or molecules is changed and covalent or ionic bonds form, physisorption does not result in changes to the chemical bonding structure.