Electrostatic effects attraction from

These effects are attributed to differences in the c-donor character of the C—C bonds as a result of substitution. Electron-attracting groups diminish the donor capacity and promote syn addition. An alternative explanation invokes a direct electrostatic effect arising from the C-X bond dipole. 

The attraction between oppositely charged colloids can be understood and modeled using the DLVO theory [3-6]. The DLVO theory links the van der Waals attraction between particles with the electrostatic effects resulting from the presence of a double layer of counterions. A detailed theoretical discussion lies outside the scope of this chapter. One of the difficulties of the DLVO theory is that an exact analytical description of interaction of overlapping double layers is only known for flat, infinite parallel surfaces. For spherical double layers, approximations need to be made or numerical theoretical simulations need to be performed. 

Because the distance between the electrons and the nucleus is increasing, the electrons are becoming further away from the nucleus, making it easier to remove them by overcoming the electrostatic force attracting them to the nucleus. Also, there are more electrons in the way, increasing interference (the electron shielding effect). 

We are all familiar with forces between bodies on a macroscopic scale. If one sits at their desk on earth pondering the view and inadvertently lets go of their lunch sandwich it falls until it lands on your manuscript, your lap or the floor—right Better yet, a cannonball and a softball fall at the same rate. It is the definition of gravity . Long after the Tower of Pisa experiments, we discovered why the moon is in seemingly stable orbit around the earth and the earth around the sun is related to forces between bodies. We are also familiar with electrostatic forces and their effects. Dust from the air in the room is attracted to the screen of everyone s TV because of the electrostatic charge it develops. It would seem reasonable that attraction occurs on a smaller scale and even on a molecular scale that does not involve energies on the order of true chemical bonds. 

The extent to which ions, etc. adsorb or experience an electrostatic ( coulombic ) attraction with the surface of an electrode is determined by the material from which the electrode is made (the substrate), the chemical nature of the materials adsorbed (the adsorbate) and the potential of the electrode to which they adhere. Adsorption is not a static process, but is dynamic, and so ions etc. stick to the electrode (adsorb) and leave its surface (desorb) all the time. At equilibrium, the rate of adsorption is the same as the rate of desorption, thus ensuring that the fraction of the electrode surface covered with adsorbed material is constant. The double-layer is important because faradaic charge - the useful component of the overall charge - represents the passage of electrons through the double-layer to effect redox changes to the material in solution. 

It is important to note that the concept of osmotic pressure is more general than suggested by the above experiment. In particular, one does not have to invoke the presence of a membrane (or even a concentration difference) to define osmotic pressure. The osmotic pressure, being a property of a solution, always exists and serves to counteract the tendency of the chemical potentials to equalize. It is not important how the differences in the chemical potential come about. The differences may arise due to other factors such as an electric field or gravity. For example, we see in Chapter 11 (Section 11.7a) how osmotic pressure plays a major role in giving rise to repulsion between electrical double layers here, the variation of the concentration in the electrical double layers arises from the electrostatic interaction between a charged surface and the ions in the solution. In Chapter 13 (Section 13.6b.3), we provide another example of the role of differences in osmotic pressures of a polymer solution in giving rise to an effective attractive force between colloidal particles suspended in the solution. 

The water dimer is the most important H-bonded system. The major attractive contribution to the interaction energy of the water dimer is the electrostatic effect. It dominates over other attractive terms, such as the induction and dispersion energies, and it is the most anisotropic. To discuss the properties of the fundamental components in the water dimer case we chose to demonstrate the angular dependence of various terms in the dimer geometry derived from the cyclic configuration of a trimer (see Fig 6). 

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