Coulombic attraction or repulsion

It was assumed above that when a concentration gradient existed in a quiescent solution, the only way the reducible ion could get to the electrode surface was by diffirsion. It can also get to the electrode surface by electrical (coulombic) attraction or repulsion. 

Shift in lEP. The intrinsic constants may be used to estimate the composition of the oxide surface as a function of solution variables (pH, concentration of specifically adsorbable cations and anions). Without correcting for coulombic attraction or repulsion such calculations should give reasonable predictions only for surfaces that have a fixed surface charge of zero (or nearly zero). Hence, it should be possible to use intrinsic constants to predict shifts in lEP caused by specific cation and anion binding. Equation 20 gives the condition for zero fixed charge (lEP). 

These domains were calculated using equilibrium constants (Table I) and corrections for coulombic attraction or repulsion. Rapid coagulation should occur in the proximity of the isoelectric line. Colloid stability is assumed to occur at positive and negative charges corresponding to a zeta potential of 30 mvolts fl8j. 

Oppositely charged ions attract each other strongly. In the gas phase the "binding" between a simple cation and a simple anion can be worth well over 100 kcal/mol. The major contributor to the binding is an electrostatic interaction. We will be discussing electrostatics extensively in this section, and it is important to be clear on its usage here. By an electrostatic interaction, we mean a strictly Coulombic attraction or repulsion between charges or partial... 

Since we have reason to believe that the order-disorder situation in ionic co-spheres, overlapping and merging as in Fig. 69, could give rise to forces of attraction or repulsion, superimposed on the Coulomb forces, we may inquire whether the observed facts as to activity coefficients may be correlated with the known behavior of the ions as regards viscosity and entropy. 

Forces Superimposed on the Coulomb Forces. The discussion has been based on the idea that, superimposed on the electrostatic forces between a pair of ions, there are rather short-range forces of other origin, which may be attractive or repulsive. Consider now what the situation will be if these forces cause the mutual potential energy to fall at short distances, below the value — e2/er that is assumed in the Debye-Hlickel theory. In Fig. 74 let the broken curve be a plot of — e2/er, while the full curve gives the actual potential energy between a certain pair of... 

The force of attraction or repulsion between two charges is called the electrostatic or coulombic force. The term electrostatic implies that the charges are stationary or fixed in position. The magnitude of the electrostatic force between two fixed point charges is given by Coulomb s law ... 

Electrostatic coulombic interactions Attractive or repulsive interactions... 

It is true that all molecular and atomic forces ultimately find their root in the mutual behavior of the constituent parts of the atoms, viz., the nuclei and the electrons. They may theoretically all be derived from the fundamental wave equations. It is, however, convenient, as in other branches of physics and chemistry, to treat the various forms of mutual interaction of atoms as different forces, acting independently. We shall therefore follow the usual procedure and treat such forces as the nonpolar van der Waals (dispersion) forces, the forces of the electrostatic polarization of atoms or molecules by ions or by dipoles, the mutual attraction or repulsion Coulomb forces of ions and of dipoles, the exchange forces leading to covalent bonds, the repulsion forces due to interpenetration of electronic clouds, together with the Pauli principle, etc., all as different, independently acting forces. 

In most organic semiconductors the presence of charges modifies the local structure of the network by deformation of the particular site. This so-called polaron formation thus creates scattering centres for other charges. Moreover these locally trapped carriers commonly alter the energy conditions because of their Coulomb interaction. In combination with the polaron energy, the latter may be attractive or repulsive. These effects, as they involve more than one electron, force us to give up the one-electron picture and hence to use the correlated-electron description. 

The algebraic signs of q and q determine whether the force is attractive or repulsive. If q and q2 are like charges, they repel F > 0), whereas opposite charges attract F < 0). In our applications to atomic and molecular structure, it is clumsy and unnecessary to carry the constant 47T6o. We will instead write Coulomb s law in gaussian electromagnetic units, whereby... 

Coulomb s law The force of attraction or repulsion of two electric charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. F = k(Q4Qb / d2), where F represents the electrostatic force, k represents a constant of proportionality, Q4 and Qb represent quantities of electrostatic charge, and d represents the distance between the charges. 

Coulomb forces result from the interaction between a charged surface and another charged or neutral surface. These forces can be attractive or repulsive, depending on the charge of each surface, and are relevant for particles with diameters larger than 5 pm [267]. For two-point electric charges separated by a distance h, Coulomb s Law gives ... 

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