Bond-dissociation energies, definition table

Table 3 Covalent Bond Dissociation Energies in [heal/mole], see eq. (7.6) for the definition of the parameters c3 and c4.

As the localized charge concept, the electronegativity concept has been the subject of several definitions [e.g. 28,29], The earliest definitions, due to Pauling [30] and Mulliken [31], involve thermodynamic or spectroscopic properties, respectively. In Pauling s scheme [30,32] electronegativities are introduced as a set of differences Xa Xb between atoms A and B of the periodic table defined from single-bond dissociation energies D(X - T) (X, Y = A, B) as ... 

For the data in Table 18 the dissociation energies of the primary valence bond, i.e. the heats of combustion had to be used, but now we must consider the energy of overcoming molecular cohesion, which is measured by the heats of sublimation and vaporization or by the van der Waals constant a. For the latter, and for the Sutherland constant closely allied to it, van Laar has already established certain additive relationships. These are expressed even more definitely in the well known Traube rule for the heats of adsorption of homologous series, which, according to Eucken, are closely related to the heats of vaporization. 

Table 8. The differences between the CR-CC(2,3) + Q(t>) and MRCI(Q) energies obtained with the aug-cc-pCVQZ (X = 4) basis between the CR-CC(2,3) + Q(b)/aug-cc-pCVQZ and ES energies and between the MRCI(Q)/aug-cc-pCVXZ (X = 4,5) and ES energies (all energies being calculated relative to their corresponding equilibrium values, as in the earlier tables), for the three cuts of the water potential energy surface (i) the dissociation of a single O-H bond, (ii) the C2 -symmetric dissociation of both O-H bonds, and (iii) the C2v dissociation into U2(X 1 Eg") and 0(2 p4 1D) (see Table 1 for the definitions of R and Y, the corresponding values of the H-O-H angle a, and the equilibrium values of R, Y, and a). All energy differences are in cm-1.

It is convenient to first establish some definitions, and these are listed in Table 6.2. As discussed in Chapter 5, as an adsorbate approaches a surface, changes occur in the potential energy of the system and one must relate this energy, Epot, to the distance, r, from the surface. It is certainly anticipated that the migration and dissociation of an adsorbate, X, on the surface involve changes in the coordination mode, Mn — X, and the M-X distance, r, where M is a metal atom and n is the coordination number. Assuming quasi-spherical interactions, a two-center M-A bond index, x, in the form of Pauling s bond order [23], is defined as... 

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