Electronic distortions

Ferre doxins 4 X S Distorted Electron Bacteria, plants. 6000-12 000 2-8... 

Hydrogen bonds are due to the attractive forces between the distorted electron cloud of a hydrogen atom and other more electronegative atoms such as oxygen and nitrogen. The attractive forces are weaker than covalent bonds, but many hydrogen bonds can be formed in macromolecular protein molecules. Van der Waals forces are weaker attractive forces, due to the attraction between neutral atoms. 

Two atoms of the same electronegativity will share electrons equally in a pure covalent bond therefore, any molecule that contains atoms of only one element, like H2 or CI2, has pure covalent bonding. Two atoms of different electronegativities, however, will have either the distorted electron distribution of a polar bond or the complete electron transfer of an ionic bond. Table 5-6 interprets the bonding between two elements as a function of the difference in their electronegativity. 

Phase transitions. Low-dimensional conductors undergo several types of specific structural phase transitions, such as the Peierls distortion (electron-phonon coupling), the spin-Peierls distortion (spin-phonon coupling), anion-ordering transitions, and so on. These first have to be detected and then measured and understood. However, the foregoing distortions may be very small and difficult to observe, and up to now, only a few lattice distortions have been fully measured and described. 

In some multisubstituted compounds, the lack of additivity needs to be noted. Proximal effects are operative and tend to distort electronic contributions. For example,... 

No. of Distribution of Predicted Distribution of Predicted d- electrons in t2g and eg- Distortion electrons in t2g and eg- Distortion... 

There is one more valuable aspect of Fajans model. Because transition metal ions have d-electrons that are relatively close to the surface of the atom, these ions themselves have somewhat distortable electron density. In other words, the electron density of transition metal cations can be distorted by the anion, causing mutual polarization of the ions. Thus, compounds that contain transition metal cations generally have more covalent character than compounds that do not have transition metal cations. 

A1 EFG tensors in the crystal frame and allowed a quantitative interpretation of the tensor element orientations and magnitudes in terms of electron densities and octahedron distortions. Electron density maps (Figure 5.13) suggested that the magnitude and orientation of the A1 EFG tensors in fluoroaluminates mainly result from the asymmetric distribution of the A1 3p orbital valence electrons. 

O. Marsalek, T. Frigato, J. VandeVondele, S. E. Bradforth, B. Schmidt, C. Schiitte, and P. Jungwirth,/. Phys. Chem. B, 114, 915-920 (2010). Hydrogen Forms in Water by Proton Transfer to a Distorted Electron. 

A cation with a high charge density distorts the electron cloud around the anion. The undistorted electron cloud is shown with a dashed line and the distorted electron cloud is shown with a solid line. The greater the distortion of the electron cloud, the greater the degree of covalency of the bond between the anion and cation. 

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