Hybrid Orbital Summary

Overall, hybrid orbitals provide a convenient model for using valence-bond theory to describe covalent bonds in molecules in which the molecular geometry conforms to the electron-domain geometry predicted by the VSEPR modeb The picture of hybrid orbitals has limited predictive value. When we know the electron-domain geometry, however, we can employ hybridization to describe the atomic orbitals used by the central atom in bonding. 

The following steps allow us to describe the hybrid orbitals used by an atom in bonding  

Use the VSEPR model to determine the electron-domain geometry around the central atom. 

Specify the hybrid orbitals needed to accommodate the electron pairs based on their geometric arrangement ( TABLE 9.4). 

These steps are illustrated in T FIGURE 9.20, which shows how the hybridization at N in NH3 is determined. 

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In view of the number and types of hybrid orbitals that are exhibited by ions of the transition metals when complexes are formed, it is possible to arrive at a summary of the most important types of complexes that each metal ion should form. Although there are many exceptions, the summary presented in Table 16.5 is a useful starting point for considering the types of complexes that are formed by metals in the first transition series. 

Conveniently, the shapes of the hybridized orbitals are identical to the shapes shown in Table 7.1. A quick summary is shown in Table 7.3. 

The AOs can be hybridized in other ways, too. One s and two p AOs can be averaged to give three new hybrid orbitals and one unchanged p orbital this procedure is called sp2 hybridization. Alternatively, one s and one p AO can be averaged to give two new hybrid orbitals and two unchanged p orbitals this procedure is called sp hybridization. In summary, the characteristics of the three kinds of hybridization are as follows ... 

Seven orbital combinations (n + 1) lead to bonding interactions within the B6 core these are shown in Figure 13-10. Constructive overlap of all six hybrid orbitals at the center of the octahedron yields one framework bonding orbital, labeled /l,.17 Additional bonding interactions are of two types overlap of two sp hybrid orbitals with parallel p orbitals on four boron atoms (three such interactions, symmetry label and overlap of p orbitals on four boron atoms within the same plane (three interactions, symmetry label t2 )- The remaining orbitals form antibonding molecular orbitals or are nonbonding. A summary follows. 

The type of hybrid orbital that forms depends on the electron geometry of the molecule. A summary of this correlation for the most common electron geometries is provided in Table 10.2. 

Several research groups have also used theoretical methods in an effort to understand the activating and deactivating effects of the substituents in S Ar reactions. For example, Galabov and coworkers have developed a computational approach for determining electrophile affinity, Ea, as a measure to determine arene reactivity and positional selectivity in S Ar reactions [36]. Other recent approaches to this problem include the development of reactive hybrid orbital analysis [37], the topological analysis of electron localization function [38], the calculations of electrostatic potentials at the arene carbons [39], and several other methods. A comprehensive summary of this area is beyond the scope of this chapter however, the interested reader may consult one of the recent reviews of this topic [40]. 

Atomic Structure The Nucleus Atomic Structure Orbitals 4 Atomic Structure Electron Configurations 6 Development of Chemical Bonding Theory 7 The Nature of Chemical Bonds Valence Bond Theory sp Hybrid Orbitals and the Structure of Methane 12 sp Hybrid Orbitals and the Structure of Ethane 13 sp2 Hybrid Orbitals and the Structure of Ethylene 14 sp Hybrid Orbitals and the Structure of Acetylene 17 Hybridization of Nitrogen, Oxygen, Phosphorus, and Sulfur 18 The Nature of Chemical Bonds Molecular Orbital Theory 20 Drawing Chemical Structures 21 Summary 24... 

Summary Ab initio calculated bond dissociation energies of silicon compounds will be discussed by means of atomic ionization energies and atomic orbital overlap. Ring strain energies of C- as well as Si-rings are estimated by homodesmotic reactions. The hybridization concept is critically examined in the case of silicon compounds. From the most important results a set of basic rules will be presented. 

Aryl halides, summary of chemistry. 223 Aspirin, 431. 440 Atomic orbitals. 13 hybridization. 17 Aufbau, 14 Axial bond. 168... 

The concept of orbital hybridization deserves a few summary comments. The method is used throughout basic and applied chemistry to give quick and convenient representations of molecular structure. The method provides a sound quantum mechanical basis for organizing and correlating vast amounts of experimental data for molecular structure. The simple examples discussed earlier all involved... 

These simple ideas were formulated before the advent of wave mechanics. Quantum theory not only justifies their use but enables us to refine and extend them. In attempting quantitative quantum-mechanical treatment of chemical bonds, approximations must be made. Traditionally, there have been two broad groups of approximations, called the valence bond (VB) and the molecular orbital (MO) treatments. The former is essentially a direct attempt to invest the qualitative ideas just outlined with quantum-mechanical validity, and it is therefore logical to continue the discussion with a summary of the valence-bond formalism, including such concepts as resonance, valence states and hybridization that arise within this framework. The molecular-orbital formalism will be presented in a following Section. 

Summary Orbital Hybridization, Bond Lengths, Bond Strengths, and Bond Angles... 

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