Structure and Strength of Ice

Ice has a special place among the solids that surround a human. The oceans cover 70% of the earth surface, and the sea ice covers about 10% of the ocean surface either seasonally or eternally. 10% of the land mass is covered with ice to depth of up to several kilometers. Ice is a factor of the global climate. It plays the leading role in polar marine transport activities. Icing occurs at airplanes and electrical transmission lines. Scientists of different specialties investigate the nature, distribution, and properties of ice. 

Ice can crystallize forming 12 different structures. At atmospheric pressure the freezing water transforms into ice termed Ih that has a hexagonal crystal lattice. The Ic ice with the cubic crystal lattice is formed at low temperatures, that is at 143 K (-130 ° C). Phases of ice other than the Ih phases are produced by the application of high pressures. 

Each H2O molecule has four nearest neighbors arranged near the vertices of a regular tetrahedron centered about the molecule of interest. The oxygen atom of each molecule is strongly covalently bonded to two hydrogen atoms, while the 

When projected onto the plane perpendicular to the c-axis, the molecular stacking sequence is. .. ABBAABBA... 

The crystal lattice parameters of ice depend on temperature. At 253 K (-20°C) parameter a = 0.4519nm and h = 0.7357 nm. The ratio c/a = 1.628 is sufficiently close to the characteristic quantity of the hexagonal unit cell. For ice it is almost independent of temperature. 

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Chapter 15 is devoted to the bonding nature in molecular and ionic crystals. We recall the dipole-dipole, dipole-induced and dispersion intermolecular forces. The van der Waals and hydrogen bonds are considered. We discuss intermolecular structure and strength of ice and the solid noble gases. The description of organic molecular crystals is presented. In conclusion we consider ionic crystals and calculate their interatomic bonding. 

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