Silicon Dioxide Silica Structure Revealed

Structure of silica | SiO4 anion unit | Silicon to oxygen ratio in silica 1 :2 | Silica SiO2 ; Silica (SiO2) is a compound with the chemical formula SiO2, based on SiO4 tetrahedra, where each silicon atom is bonded to four oxygen atoms in a tetrahedral arrangement. The central silicon atom in each SiO4 unit is sp3 hybridized, forming four equivalent Si-O bonds with a bond angle of 109.5°. Each oxygen atom is shared between two adjacent silicon atoms, forming a continuous three-dimensional network. This sharing of oxygen atoms results in a 1:2 ratio of silicon to oxygen in silica, resulting in the molecular formula SiO2. The repeating pattern of SiO4 tetrahedra linked by shared oxygen atoms creates a three-dimensional structure with 8-membered rings. Silica can exist in various crystalline forms, such as quartz, cristobalite, and tridymite, as well as in amorphous forms like opal and glass. The molecular formula is SiO2 because each oxygen atom is shared between two silicon atoms, effectively halving the number of oxygen atoms per silicon atom. Silica exhibits polymorphism, allowing it to exist in multiple crystalline forms with different structures and properties. The most common polymorphs of silica include quartz, cristobalite, and tridymite, each with distinct arrangements of silicon-oxygen tetrahedra.