Group lattice energies

Various HNFX models, space groups, lattice energies (E, kcal mol 1) and densities (p, g cm 3)... 

Incidentally it must be noted that the interaction energy of Mg with C03 does not correspond to the lattice energy of the crystalline substance, but is about Vio of its value. Most of the cohesive energy is due to the covalent bonds within the CO group. 

Table 5.37 lists the various terms of the lattice energy of some clinopyroxene components. Data refer to the C2/c spatial group. Components Mg2Si206 and Fe2Si20g, which crystallize in Pljlc, must thus be considered fictitious. ... 

Thiourea forms MX (thiourea) 4 compounds if the lattice energy of MX is iess than 160 Kcal/mole, so that M = K, Rb, or Cs. Other large cations form similar compounds, for example, thallium and lead. The structures consist of columns of cations surrounded by eight sulphur atoms at the comers of an approximately regular cube. Each sulphur atom is shared by two cations. The S—C bonds lie in planes normal to the column, and the NHg groups project into channels which contain the anion, and sometimes water molecules (34). 

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