Correlation between structure and enthalpy properties of alkaline and alkali-earth metals mеtа- and orthosilicates

Using equations of model of effective ionic radii, metamorphosis of crystalline structures into cubic ones and enthalpies of a crystal lattice on the basis of X-ray and thermodynamic data of alkaline (Na, K), alkaline-earth (Ca, Sr, Ba) metasilicates and alkaline-earth (Ca, Sr, Ba) orthosilicates for the first time calculated standart energy of formation (SiO 2- 3, g), namely 715,65±0,07 kJ·mole -1. For Rb, Cs, Fr, Ra metasilicates and Ra orthosilicates it is estimated their enthalpies of interstructural interactions, enthalpies of crystal lattices and standart energy of formation.