Chemistry · Ch 9 — Elements of Group 13, 14 and 15
Silicon dioxide (SiO2)
Silicon dioxide (SiO2)
Silicon dioxide, commonly called silica, is a covalent, three-dimensional network solid rather than a discrete molecule: every silicon atom is covalently bonded, in a tetrahedral arrangement, to four oxygen atoms, and each of those oxygen atoms in turn bridges to a second silicon atom, so the whole crystal is one continuous covalent framework built from linked SiO4 tetrahedra, with the crystal lattice containing eight-membered rings of alternating silicon and oxygen atoms (see the SiO2-structure figure note). Silica occurs in several interconvertible crystalline forms — quartz, cristobalite and tridymite are the most familiar …
What this figure shows. Silicon dioxide is drawn as an extended three-dimensional covalent network rather than a discrete molecule: each silicon atom sits at the centre of a tetrahedron of four oxygen atoms, and each oxygen atom is shared between (bridges) two silicon tetrahedra, so the whole diagram is a repeating lattice of corner-sharing SiO4 tetrahedra. The diagram highlights eight-membered rings within this lattice, made of alternating silicon and oxygen atoms, the specific ring motif the running text calls …