Phosphorus valence molecular orbitals

The P2 molecule contains phosphorus atoms from the third row of the periodic table. We will assume that the diatomic molecules of the Period 3 elements can be treated In a way very similar to that which we have used so far. Thus we will draw the MO diagram for P2 analogous to that for N2. The only change will be that the molecular orbitals will be formed from 35 and 2p atomic orbitals. The P2 model has 10 valence electrons (5 from each phosphorus atom). The resulting molecular orbital diagram is... 

An explanation for the existence of the very different kinds of lattices that are observed for the various nonmetals demands a profound knowledge of the possible ways in which the valence electrons of these elements can be arranged. This information is only available from the performance of suitable molecular orbital calculations, which yield detailed information about the distribution of electron density in the components of a unit cell. For instance, only such computational methods can show why phosphorus forms P molecules in the vapor phase and why these same molecular species are again encountered in the lattice of white phosphorus. 

The electrical conductivity of a semiconductor is influenced by the presence of small numbers of impurity atoms. The process of adding controlled amounts of impurity atoms to a material is known as doping. Consider what happens when a few phosphorus atoms (known as dopants) replace silicon atoms in a silicon crystal. In pure Si all of the valence-band molecular orbitals are filled and all of the conduction-band molecular orbitals are empty, as T FIGURE 12.32(a) shows. Because phosphorus has five valence electrons but... 

The electrical conductivity of a semiconductor is influenced by the presence of small numbers of impurity atoms. The process of adding controlled amounts of impurity atoms to a material is known as doping. Consider what happens when a few phosphorus atoms (known as dopants) replace silicon atoms in a silicon crystal. In pure Si all of the valence-band molecular orbitals are filled and all of the conduction-band molecular orbitals are empty, as A Figure 12.31(a) shows. Because phosphorus has five valence electrons but silicon has only four, the extra electrons that come with the dopant phosphorus atoms are forced to occupy the conduction band [Figure 12.31(b)]. The doped material is called an n-type semiconductor, n signifying that the number of negatively charged electrons in the conduction band has increased. These extra electrons can move very easily in the conduction band. Thus, just a few parts per million (ppm) of phosphorus in silicon can increase silicon s intrinsic conductivity by a factor of a million ... 

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... 

For complexes of type MP (P = phosphorus ligand), where the acceptor atom M has an environment with microsymmetry that is Tj or Of, it is possible to simplify equation (1) considerably, because the only valence shell atomic orbital on the acceptor atom belonging to the totally symmetric representation of the molecular space group is the i orbital. This means that other atomic orbitals on the acceptor atom do not mix with the s orbital and that only totally symmetric ligand combinations need be considered. 

The five HCP valence orbitals (5a through 2jt) are dominated by localized bonding descriptions similar to those of HCN (Table 28). The only differences are that the 6a bond in HCP has some P—C bond character in addition to the C—H bond contribution, and the lone pair electrons are more diffuse on the phosphorus than on nitrogen. The molecular structures of HCN, HCP and a number of substituted species have been determined by microwave techniques. Although studies of the nitriles are well advanced due to the stability of the species and the ease of obtaining the various isotopomers, data on the phosphaalkynes are less complete. The latter are studied by pyrolysis of organophosphorus precursors in flow systems, making isotopic substitution experiments more difficult and costly. In many cases. 

To describe hybridization schemes that correspond to the 5- and 6-electron-group geometries of VSEPR theory, we need to go beyond the s and p subshells of the valence shell, and traditionally this has meant including d-orbital contributions. We can achieve the five half-filled orbitals of phosphorus to account for the five P—Cl bonds in PCI5 and its trigonal-bipyramidal molecular geometry through the hybridization of the s, three p, and one d orbital of the valence shell into five sp d hybrid orbitals. 

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