The spatial structure of silicon dioxideWhy is the smallest ring in silicon dioxide the 12 membered ring made up of 6 Si atoms and 6 O atoms?
Si is a tetrahedron mesh structure, that is, each silicon atom forms a regular tetrahedron with four oxygen atoms around it.O is inserted in the center of the Si-Si bond
Its structure can be thought of as 4 oxygen atoms on a triangular, polyhedral foot. The center of the polyhedron is a silicon atom. In this way, each of the 4 oxygen atoms covalently bonded to the silicon atom approximation, satisfy the valence shell of silicon. If each oxygen atom is part of the two polyhedron, then the valence of oxygen was satisfied, the result became known as the quartz crystal structure of the rules. In fused silica, some oxygen atoms are bridged by oxygen atoms and bonded to two silicon atoms. Some oxygen atoms do not have oxygen bridges and are bonded only to one silicon atom. It can be argued that thermally grown silica is mainly composed of a polyhedral network of oriented individuals. Compared with the oxygen free bridge, the larger the oxygen bridge, the greater the adhesive force of the oxide layer, and the smaller the tendency to damage. The ratio of aerobic bridge to oxygen free bridge is much larger than that of wet oxide. Therefore, SiO2 can be considered as an atomic crystal rather than an ionic crystal. Transition from valence bond between oxygen atom and silicon atom to ionic bond.
The spatial structure of silicon is similar to that of diamond. The crystal structure of silicon dioxide is equivalent to inserting a O atom between each Si-Si bond. The formation of C diamond minimum is a hexagon, so Si is, because the space structure of silica is equivalent to the insertion of a O atom in each of the Si-Si bonds, so the small silica is twelve membered ring composed of 6 oxygen atoms and 6 silicon atoms
