Atomisation enthalpies Table

These points are well illustrated by comparing Cu, Ag and Au with respect to the relative stabilities of their oxidation states. Although few compounds formed by these elements can properly be described as ionic, the model can quite successfully rationalise the basic facts. The copper Group 1 Id is perhaps the untidiest in the Periodic Table. For Cu, II is the most common oxidation state Cu(I) compounds are quite numerous but have some tendency towards oxidation or disproportionation, and Cu(III) compounds are rare, being easily reduced. With silver, I is the dominant oxidation state the II oxidation state tends to disproportionate to I and III. For gold, III is the dominant state I tends to disproportionate and II is very rare. No clear trend can be discerned. The relevant quantities are the ionization energies Iu l2 and A the atomisation enthalpies of the metallic substances and the relative sizes of the atoms and their cations. These are collected below / and the atomisation enthalpies AH%tom are in kJ mol-1 and r, the metallic radii, are in pm. 

Table 6.2 Mean bond energies from atomisation enthalpies at 25 °C of gaseous molecular substances, in kJ molRanges of values are not given in cases where the relevant data are available only for one or two molecules...

A satisfactory theory of metallic bonding must account for the characteristic properties of high electrical and thermal conductivity, metallic lustre, ductility and the complex magnetic properties of metals which imply the presence of unpaired electrons. The theory should also rationalise the enthalpies of atomisation A/f tom of metallic elemental substances. A/f tom is a measure of the cohesive energy within the solid, and we saw in Chapter 5 how it plays an important part in the thermochemistry of ions in solids and solutions. The atomisation enthalpies of elemental substances (metallic and nonmetallic) are collected in Table 7.1. There is a fair correlation between A/Z tom an(J physical properties such as hardness and melting/boiling points. 

Table 7.1 Atomisation enthalpies of elemental substances (kJ mol 25 °C), or enthalpies of formation of gaseous monatomic substances E(g)... 

Table 11.1 and Table 11.2 (p. 314) give some of the physical properties of the common halogens. Figure 11.1 shows graphically some of the properties given in Table 11.1, together with enthalpies of atomisation. 

Table Properties of alkali metals melting and boiling points, atomisation and ionisation enthalpies, ionic and standard electrode potentials...

The atomisation energies of the gaseous species were recalculated from 0 to 298.15 K using the values of H° (T) - H° (0 K) given in Table 3 of the paper. Enthalpies of formation were calculated from the atomisation energies at 298.15 K and the selected data of Se(g) and the enthalpy of formation of Mn(g) in [82WAG/EVA], The results are given in Table A-107. 

Table A-107 Atomisation energies and enthalpies of formation derived from measurements in [78SMO/PAT].

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