Electron pair distribution

VSEPR Model valence shell electron pair repulsion model, model used to predict the geometry of molecule based on distribution of shared and unshared electron pairs distributed around central atom of a molecule... 

Table 5.1 contains the basic shapes adopted by the indicated numbers of a electron pairs, and Figure 5.3 shows representations of the basic shapes assumed by the various electron pair distributions. The bond angles (the angles formed by ligand-central atom-ligand triplets) are included in Table 5.1. 

Number of o electron pairs Distribution of electron pairs Bond angles Type of hybridization... 

Q The valence shell of the central atom of a molecule possesses two bonding and three non-bonding pairs of electrons. State, with reasoning, the shapes of (i) the electron pair distribution and (ii) the molecule. 

In what directions can five electron pairs arrange themselves in space so as to minimize their mutual repulsions In the cases of coordination numbers 2, 3, 4, and 6, we could imagine that the electron pairs distributed themselves as far apart as possible on the surface of a sphere the resulting shapes correspond to the regular polyhedron whose number of vertices is equal to the coordination number. 

Species requiring multiple Lewis structures often involve electron delocalization with some electron pairs distributed over more than two atoms. 

Since there are six electron pairs distributed over the three Re—Re edges of the Re3 triangle, or two pairs per Re—Re interaction, the MO picture is formally equivalent to describing each Re—Re bond as a double bond, consisting of a a bond and a n bond perpendicular to the Re3 plane. 

Now we are going to introduce several useful concepts, such as the electron pair distribution function and the electron hole (in a more formal way than we did in Chapter 10, p. 597), etc. 

In each of these choices, there is a lot of ambiguity. This, however, is restricted by some physical requirements. The requirements are related to the electron pair distribution function n(ri,r2) = N(N — 1) Q,. / pd -3dr4. .. Arpi, which takes into account that the two electrons, shown by r and 1-2, avoid... 

CS, charge shift bond (p. 705) density matrix (p. 6651 electron gas (p. 7061 electronic density (p. 665) electron pair distribution (p. 690)... 

Poater et al. analysed the effects of solvation on the pairing of electrons in molecules in a series of molecules and in the Menshutkin reaction between ammonia and methyl chloride. AIM atomic populations and localization and delocalization indices have been used for describing the electron-pair characteristics. This analysis shows that solute-solvent interactions modify the electron-pair distribution of the solute increasing the polarization of the molecular bonds. 

The requirements are related to the electron pair distribution function... 

Figure 23 Predicted structure of hydrogen plasma by HNC-TFW method in comparison with ab initio calculations (A) proton-electron pair distribution function at electron density rj = 1 and temperature T = 10,000 K (B) the proton-proton pair distribution function at electron density Tj = 1 and temperature T = 3000 K. After Hong (2002).

Earlier, we drew Lewis diagrams in which carbon, nitrogen, or oxygen was the central atom. In all cases the central atom was surrounded by four pairs of electrons. In Section 12.7 we showed how beryllium and boron—also Period 2 elements—do not conform to the octet rule. The beryllium atom in BeF2 is flanked by only two electron pairs in BEj, the boron atom has three electron pairs around it. Our question then is this How do two, three, or four electron pairs distribute themselves around a central atom so they are as far apart as possible This question is answered by identifying the electron-pair angle, the angle formed by any two electron pairs and the central atom. 

Yet, the correspondences as central atom = interstitial ligands = coordination polyhedron generates a functional paradigm which qualitatively rationalizes the chemical bond, emphasizing on the electronic pairs distributed in geometric-symmetrical way. 

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