Hybrid orbitals naming

In most metals the electron behaves as a particle having approximately the same mass as the electron in free space. In the Group IV semiconductors, dris is usually not the case, and the effective mass of electrons can be substantially different from that of the electron in free space. The electronic sUmcture of Si and Ge utilizes hybrid orbitals for all of the valence elecU ons and all electron spins are paired within this structure. Electrons may be drermally separated from the elecU on population in dris bond structure, which is given the name the valence band, and become conduction elecU ons, creating at dre same time... 

Unsaturated organic molecules, such as ethylene, can be chemisorbed on transition metal surfaces in two ways, namely in -coordination or di-o coordination. As shown in Fig. 2.24, the n type of bonding of ethylene involves donation of electron density from the doubly occupied n orbital (which is o-symmetric with respect to the normal to the surface) to the metal ds-hybrid orbitals. Electron density is also backdonated from the px and dM metal orbitals into the lowest unoccupied molecular orbital (LUMO) of the ethylene molecule, which is the empty asymmetric 71 orbital. The corresponding overall interaction is relatively weak, thus the sp2 hybridization of the carbon atoms involved in the ethylene double bond is retained. 

Any hybrid orbital is named from the atomic valence orbitals from which It Is constmcted. To match the geometry of methane, we need four orbitals that point at the comers of a tetrahedron. We construct this set from one s orbital and three p orbitals, so the hybrids are called s p hybrid orbitais. Figure 10-8a shows the detailed shape of an s p hybrid orbital. For the sake of convenience and to keep our figures as uncluttered as possible, we use the stylized view of hybrid orbitals shown in Figure 10-8Z). In this representation, we omit the small backside lobe, and we slim down the orbital in order to show several orbitals around an atom. Figure 10-8c shows a stylized view of an s p hybridized atom. This part of the figure shows that all four s p hybrids have the same shape, but each points to a different comer of a regular tetrahedron. 

For each of the following Lewis structures, name the electron group geometry and the hybrid orbitals used by the inner atoms. 

Hybridization occurs between two or more different types of orbitals (generally s, p or d orbitals). For example, there are three types of hybrid orbitals which may occur between the s and p orbitals, these are named as sp, sp2 and sp3 hybrid orbitals. 

Overlapping orbitals Name of hybrid Geometry Example... 

The group orbitals of a zero-coordinated atom are not just the set of four valence orbitals of the atom, namely s, px, py, and pz. because we will assume that for the purposes of deducing orbital interactions, it is our intention to make a and possibly n bonds to the uncoordinated atom. Because two orbitals of the atom, s and px, will each interact in a a fashion with a nearby atom, we mix these beforehand to form two new hybrid orbitals, one of which will interact maximally with the neighboring atom because it is pointed right at it, and another which will be polarized away from the second atom and therefore will interact minimally with it. The group orbitals of such a zero-coordinated atom are shown in Figure 3.14. 

The SHMO theory was originally developed to describe planar hydrocarbons with conjugated n bonds. Each center is sp2 hybridized and has one unhybridized p orbital perpendicular to the trigonal sp2 hybrid orbitals. The sp2 hybrid orbitals form a rigid unpolarizable framework of equal C—C bonds. Hydrogen atoms are part of the framework and are not counted. The Hiickel equations (3.3) described in the first part of Chapter 3 apply, namely,... 

This is as far as symmetry arguments alone will take us and we can only conclude that the most general solution to the problem would be a set of hybrid orbitals which are linear combinations of both pos-sibiUties, namely = a(gp>) +6(8d>)... 

It is clear that if the repulsive fields are operative in those regions where hae is small, namely, in the areas labeled F in the diagrams, then hae may be considerably more stable than kag and, indeed, more stable than either of the original orbitals, sae and dag. Regarding the field as a perturbation, we see that the effect of the field on the dag and sag orbitals is to mix them in such a way as to produce one orbital, haR, which is more stable than either and another, kag, which is more highly excited. If there are two electrons of ag type, therefore, these will be most firmly bound in the hybrid orbital hag, and not in either sag or dag. (The precise values of the coefficients determining the amount of hybridiza-... 

Pauling showed that the quantum mechanical wave functions for s and p atomic orbitals derived from the Schrodinger wave equation (Section 5.7) can be mathematically combined to form a new set of equivalent wave functions called hybrid atomic orbitals. When one s orbital combines with three p orbitals, as occurs in an excited-state carbon atom, four equivalent hybrid orbitals, called sp3 hybrids, result. (The superscript 3 in the name sp3 tells how many p atomic orbitals are combined to construct the hybrid orbitals, not how many electrons occupy each orbital.)... 

There are several types of hybrid orbitals sp sp2 sp dsp- d spl etc. In order to figure out the type of hybrid orbital formed by an atom on the MCAT, simply count the number of sigma bonds and lone pairs of electrons on that atom. Match this number to the sum of the superscripts in a hybrid name (letters without superscripts are as- H sumed to have the superscript l ). Remember,... 

All the elements of a group A family have the same number of bonds when a molecule is formed. In addition, these bonds all originate in the same orbitals. In Chapter 6 we learned the names of the orbitals where the outermost electrons reside. These orbitals are the places where bonds form with other atoms. The shape and orientation of these orbitals determine the geometric shape of resulting molecules when a group A atom bonds with other atoms. Before this information is summarized, it is necessary to consider how some orbitals combine to form hybrid orbitals when bonds are formed. 

Alkynes are unsaturated hydrocarbons containing at least one triple carbon-carbon bond. The simplest alkyne is C2H2 (commonly called acetylene), which has the systematic name ethyne. As discussed in Section 14.1, the triple bond in acetylene can be described as one cr bond between two sp hybrid orbitals on the two carbon atoms and two v bonds involving two 2p orbitals on each carbon atom (Fig. 22.10). 

In the case of hydrocarbons, the calculation still comprises five parameters, namely two Coulomb integrals ac and h, two bonds, resonance integrals /Sec and /Sqh and one resonance integral for two orbitals centered on the same carbon Ice- As usual, the interaction terms between non-bonded atoms are neglected. The parameters a and /3 are the matrix elements of a non-specified effective Hamiltonian with respect to the sp3 or sp2 hybrid orbitals of carbon and the Is orbitals of hydrogens. For the a bonds of conjugated hydrocarbons 4S>, the following set of values has been used... 

Hybrid orbitals are named by indicating the number and kind of atomic orbitals hybridized. Hybridization of one s orbital and onep orbital gives two sp hybrid orbitals. We shall see presently that hybridization of one s and two p orbitals gives three sp hybrid orbitals hybridization of one s orbital and three p orbitals gives four sp hybrids, and so on (see Table 8-2). 

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