Antibonding molecular orbital, definition

Definitions. Define and illustrate each of die following terms (a) bonding molecular orbital, (b) antibonding molecular orbital, (c) a bond, (d) tt bond, (e) nonbonding electrons, (f) conduction band, (g) forbidden zone, (h)... 

Earlier in this chapter, you learned the definition of bond order in the valence bond theory. In molecular orbital theory, the bond order is defined as one-half the difference between the number of electrons in bonding orbitals and the number of electrons in antibonding orbitals. Mathematically, this can be expressed as... 

Application of the criteria (l)-(4) in molecular dynamic calculations employing the SPC/E water model for obtaining the numbers of HBs per water molecule x at 300 K yielded between 3.2 and 3.4 such bonds. Double-donor water molecules provided according to criterion (3) 1.66 HBs, the rest coming from acceptor molecules (Kumar et al. 2007). These authors also considered electronic structure definitions for the occurrence of HBs between water molecules. Considering the electron donor-acceptor nature of the HB (rather than the hydrogen atom donor-acceptor mode discussed above), the relevant molecular orbital is the o-qh antibonding one of the acceptor that is empty in monomeric water. The occupancy of this orbital, once HBs are formed in liquid water, is the criterion to be used ... 

Two different bonding indiees will be used in this book, namely bond-number and bond-order. The bond number refers to the number of pairs of electrons that form a covalent bond. It may be calculated from the weights of the valence-bond structures that are used to describe the electronic structure of the molecule, as is demonstrated above for N2O. The bond-order is a molecular orbital index of bonding. For the purpose of qualitative discussion of diatomic bonding, we shall define the bond-order to be /4 (No. of bonding electrons) - (No. of antibonding electrons). Another definition of bond-order will be introduced in Chapter 14. 

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