Valence molecular orbital energies

Step 2 Use matching valence-shell atomic orbitals to build bonding and antibonding molecular orbitals and draw the resulting molecular orbital energy-level diagram (Figs. 3.31 and 3.32). 

FIGURE 3.37 The molecular orbital energy-level diagram for methane and the occupation of the orbitals by the eight valence electrons of the atoms. 

FIGURE 3.40 The molecular orbital energy-level diagram for SFf, and the occupation of the orbitals by the 12 valence electrons of the atoms. Note that no antibonding orbitals are occupied and that there is a net bonding interaction even though no d-orbitals are involved. 

FIGURE 21.7 Molecular orbital energy levels for Na molecules. A crystal of sodium metal can be regarded as a giant Na molecule, where n has a value of about 1020. As the value of n increases, the energy levels merge into an almost continuous band. Because each Na atom has one 3s valence electron and each MO can hold two electrons, the 3s band is half-filled. In this and subsequent figures, the deep red color denotes the filled portion of a band. 

Figure 4.17 Correlations between transition energies of Fe2+ — Fe3+ IVCT bands and metal-metal distances of several mixed-valence minerals (modified from Mattson Rossman, 1987a). Circles edge-shared octahedra squares face-shared octahedra cross calculated from molecular orbital energy level calculations ( 11.7.3 Sherman, 1987a). The key to the symbols is given in table 4.2, p. 117.

TABLE 11. Ionization energies (eV) for ionizations from the valence molecular orbitals of EHal2 and their assignmentsa... 

In this cluster, which has C2, symmetry, the calculated molecular-orbital energy levels should be compcu-ed with those of the FeO cluster in Fig. 4.26(a). As for the latter cluster, the molecular orbitals can be grouped into sets in relation to their atomic-orbital character, with the dominantly Fe 3d (crystal-field-type) orbitals being at the top of the valence band. Now, however, as shown in Fig. 4.29, the orbitals below these in energy fall into four groups O 2p nonbonding orbitals, Fe-(9... 

Fig. 11.7 Molecular orbital energy diagram for a square prism arrangement of 16 atoms, each one contributing a valence s orbital.

FIGURE 2. Shape of valence molecular orbitals of aniline. Due to its Cs symmetry, the MOs are characterized by a and a" irreducible representations, but they are continuously numbered without dividing them into two subsets, s denotes the orbital energy computed using the HF/6-311++G(d,p) wavefunction... 

Second-row elements have 2s and 2p valence orbitals. Interactions between these orbitals give the molecular orbital energy level diagram shown in Figure 2-4. The molecule 02 is an example of this arrangement. 

Place the appropriate number of electrons in the molecular orbital energy levels by first determining the total number of valence electrons in the molecule or ion and then placing these in the molecular orbitals, starting with the lowest energy MO. Hund s rule and the Pauli exclusion principle should be followed. 

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