Electrons electron-pair repulsion model

VSEPR model Valence Shell Electron Pair Repulsion model, used to predict molecular geometry states that electron pairs around a central atom tend to be as far apart as possible, 180-182... 

The Lewis structures encountered in Chapter 2 are two-dimensional representations of the links between atoms—their connectivity—and except in the simplest cases do not depict the arrangement of atoms in space. The valence-shell electron-pair repulsion model (VSEPR model) extends Lewis s theory of bonding to account for molecular shapes by adding rules that account for bond angles. The model starts from the idea that because electrons repel one another, the shapes of simple molecules correspond to arrangements in which pairs of bonding electrons lie as far apart as possible. Specifically ... 

Example the n = 2 shell of Period 2 atoms, valence-shell electron-pair repulsion model (VSEPR model) A model for predicting the shapes of molecules, using the fact that electron pairs repel one another. 

Having introduced methane and the tetrahedron, we now begin a systematic coverage of the VSEPR model and molecular shapes. The valence shell electron pair repulsion model assumes that electron-electron repulsion determines the arrangement of valence electrons around each inner atom. This is accomplished by positioning electron pairs as far apart as possible. Figure 9-12 shows the optimal arrangements for two electron pairs (linear),... 

Once computed on a 3D grid from a given ab initio wave function, the ELF function can be partitioned into an intuitive chemical scheme [30], Indeed, core regions, denoted C(X), can be determined for any atom, as well as valence regions associated to lone pairs, denoted V(X), and to chemical bonds (V(X,Y)). These ELF regions, the so-called basins (denoted 2), match closely the domains of Gillespie s VSEPR (Valence Shell Electron Pair Repulsion) model. Details about the ELF function and its applications can be found in a recent review paper [31],... 

The VSEPR (Valence shell electron pair repulsion) Model... 

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... 

The distortion produced by the lone pairs is traditionally described using the Valence Shell Electron Pair Repulsion Model (VSEPR model) (Gillespie and Hargittai 1991), which assumes that each pair of electrons in the valence shell is... 

In the valence-shell electron-pair repulsion model, or VSEPR model, we focus attention on the central atom of a molecule, such as the B atom in BF3 or the C atom in C02. We then imagine that all the electrons involved in bonds to the central atom and the electrons of lone pairs belonging to that atom lie on the surface of an invisible sphere that surrounds it (Fig. 3.3). These bonding electrons and lone pairs are regions of high electron concentration, and they repel one another. To minimize their repulsions, these regions move as far apart as possible on the surface of the sphere. Once we have identified the most distant ... 

Suppose that we wish to construct an LCAO bonding model for methane. We set up the problem by defining an, y, z coordinate system and placing the carbon at the origin. The molecule is tetrahedral, as determined from the electron-pair repulsion model. The orientation of the molecule is arbitrary we choose to arrange it as shown in 21, with the hydrogen atoms in the +x, +y, + z quadrant, the —x, —y, +z quadrant, the +, —y, —z quadrant, and the —x, +y, —z quadrant. 

R. J. Gillespie, Electron-Pair Repulsion Model for Molecular Geometry, J. Chem. Educ. 1970, 47, 18. R. J. Gillespie, Molecular Geometry, Van Nostrand Reinhold Co., London, 1972. 

This chapter reviews molecular geometry and the two main theories of bonding. The model used to determine molecular geometry is the VSEPR (Valence Shell Electron Pair Repulsion) model. There are two theories of bonding the valence bond theory, which is based on VSEPR theory, and molecular orbital theory. A much greater amount of the chapter is based on valence bond theory, which uses hybridized orbitals, since this is the primary model addressed on the AP test. 

The structures of the binary fluorides are predictable on the basis of the valence shell electron pair repulsion model (see Chapter 2). With eight valence shell electrons from the xenon atom and two additional electrons from the two fluorine atoms, there are 10 electrons surrounding the xenon atom in XeF2. Thus, the structure of XeF2 has Doah symmetry as shown here ... 

A. Schmiedekamp, D. W. J. Cruickshank, S. Skaarup, P. Pulay, I. Hargittai, J. E. Boggs, Investigation of the Basis of the Valence Shell Electron Pair Repulsion Model by ab Initio Calculation of Geometry Variations in a Series of Tetrahedral and Related Molecules. J. Am. Chem. Soc. 1979, 101, 2002-2010. 

Some simple rules were supported by empirial evidence, valence shell electron pair repulsion model (VSEPR) and MO calculations, both semiempirical and ab initio. These rules could explain those features of molecular geometry which have been characterized by structural investigations using spectroscopic and diffraction techniques. 

The geometric structure of the covalent binary halides, whether neutral or complexed ions, can be explained on the basis of the Nyhotm-Gillespie rules known as the Valence Shell Electron Pair Repulsion Model (VSEPR) theory the geometrical arrangements of the bonds around an atom in a species depends on the total number of electron pairs in the valence shell of the central atom, including both bonding... 

The Valence Shell Electron-pair Repulsion Model... 

Tetranuclear monoadducts with asymmetrical M- O M bridges related to those of [M2OCI9] have been characterized but most structural data concern monomeric NbOCls bis adducts. In such derivatives, the metal is octahedrally surrounded with the neutral Ugands cis to each other, one being trans to the 0x0 bond, which is short (typical Nb=0 Bond Length 1.70 A). The coordination polyhedron is distorted as a result of the niobium-oxygen multiple bond (see Valence Shell Electron Pair Repulsion Model). ... 

AU acceptable theories should account for the following facts only the heavier, more readily ionizable noble gases form compounds and only the most electronegative atoms or groups are satisfactory hgands for the noble gases. Two theories of bonding in noble gas compounds are discussed here see also Molecular Orbital Theory and Valence Shell Electron Pair Repulsion Model). 

The P-donor ligands we consider in this Part I are phosphoms(III) compounds. We avoid the classification difficulties of phosphine, PH3, as based on P-oxidation state —HI by referring throughout to tervalent phosphoms. Low-coordination number phosphorus species, such as RP, RCP, R2C=PR, and P , are presented in Part II. The P-donor ligands considered in Part I are covered by the generalized formula PR3 for a P-donor ligand. The PR3 ligands have a pyramidal shape due to their sterically active lone pair of electrons. In terms of a Valence Shell Electron Pair Repulsion Model model, the lone pair occupies the vacant tetrahedral site of the phosphoms center. 

Molecular geometry and the valence-shell electron pair repulsion model... 

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