Force of electrostatic repulsion

Rutherford s atomic model solved problems inherent in Thomson s atomic model, but it also raised others. For example, an atomic nucleus composed entirely of positive charges should fly apart due to electrostatic forces of repulsion. Furthermore, Rutherford s nuclear atom could not adequately explain the total mass of an atom. The discovery of the neutron, in 1932, eventually helped to settle these questions. 

In considering the physical forces acting in fission, use may be made of the Bohr liquid drop model of the nucleus. Here it is assumed that in its uonual energy state, a nucleus is spherical and lias a homogeneously distributed electrical charge. Under the influence of the activation eneigy furnished by the incident nentron, however, oscillations are set up which tend to deform the nucleus. In the ellipsoid form, the distribution of the protons is such that they are concentrated in the areas of the two foci. The electrostatic forces of repulsion between the protons at the opposite ends of the ellipse may then further deform the nucleus into a dumbbell shape. Rrom this condition, there can be no recovery, and fission results. 

The stability of latexes during and after polymerization may be assessed at least qualitatively by the theoretical relationships describing the stability of lyophobic colloids. The Verwey-Overbeek theory (2) combines the electrostatic forces of repulsion between colloidal particles with the London-van der Waals forces of attraction. The electrostatic forces of repulsion arise from the surface charge, e.g., from adsorbed emulsifier ions, surface sulfate endgroups introduced by persulfate initiator, or ionic groups introduced by using functional monomers. These electro-... 

The old conception of solution pressure of a metal can now be replaced by this difference in energy levels between the positive ions in the metal and in the solution. In the metal the ions are held by chemical forces to the other positively charged ions, and by electrostatic forces to the electrons or perhaps it would be more correct to say that the electrons neutralize the electrostatic forces of repulsion which would otherwise tend to drive the positive ions apart. In the solution, they are bound to solvent molecules. It is therefore the pull on the ions caused by the difference in energy levels in the solution, and in the metal, that tends to drag the metal ions into solution. 

In conventional latices, the colloidal stability of the particles arises from the predominance of the electrostatic forces of repulsion over the London-van der Waal s forces of attraction. These electrostatic forces of repulsion result from the electric double layer formed by the emulsifier ions adsorbed on the hydrophobic polymer particle surface and the counterions from the aqueous phase. The London-van der Waal s forces of attraction are strongest when the particle-particle distance is very small. Therefore, in most particle-particle collisions, the particles repel one another until the particle-particle distance is decreased to the point where the London-van der Waal s forces of attraction are predominant over the electrostatic forces of repulsion. Thus, many conventional latices remain stable indefinitely without significant stratification or flocculation of the particles. 

On the basis of work done in the years just before World War II, Deijaguin and Landau [26] were able to explain in 1941 many of the complex phenomena involved in aggregative stability on the basis of forces of interaction between colloidal particles, namely the van der Waals-London forces of attraction and the electrostatic forces of repulsion. In the meantime, as a result of theoretical investigations and calculations performed in the years 1940-1944 and without the benefit of much of the literature that appeared during the war years, Verwey and Overbeek [7] formulated a theory of stability of lyophobic colloids and published it as a book in 1948. Because their... 

In expoimental terms this effect has beat danmstrated by direct measurenients of the electrostatic force of repulsion bm eai bvo crossed mica hetnic lindos [8,9]. For this situation the electrostatic force of repulsion, F i, is given by... 

Because the increase in the electrostatic force of repulsion is inversely proportional to the distance between the two surfaces, the force was gradually increased with the thinning of the foam film. This repulsion force would prevent further thinning when a certain thickness was reached in the foam film, and the rupture would occur with further elongation. We described the relationship between the magnitude of this repulsive force and the thickness of the foam film in the previous section (Sec. III-D). 

The type (4) employs an electrostatic force of repulsion between photogenerated charges as a driving force of a conformational change. Triphenylmethane leucoderivatives have been used as photoreceptor molecules in order to produce positive charges in the pendant groups of polymers.The chromophore dissociates into an ion-pair under ultraviolet irradiation with production of an intensely colored triphenylmethyl cation. The cation thermally recombines with the counter anion as follows. 

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