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Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO 2, commonly found in nature as quartz. [ 5 ] [ 6 ] In many parts of the world, silica is the major constituent of sand .
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide).The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2.
In mineralogy, silica (silicon dioxide, SiO 2) is usually considered a silicate mineral rather than an oxide mineral. Silica is found in nature as the mineral quartz , and its polymorphs . On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working ...
It has the diamond structure but with linked tetrahedra of silicon and oxygen where the carbon atoms are in diamond. A chiral tetragonal form called α-cristobalite (space group either P4 1 2 1 2, No. 92, [ 9 ] or P4 3 2 1 2, No. 96, at random) occurs on cooling below about 250 °C at ambient pressure and is related to the cubic form by static ...
Oxidation of organosilicon compounds, including siloxanes, gives silicon dioxide. This conversion is illustrated by the combustion of hexamethylcyclotrisiloxane: ((CH 3) 2 SiO) 3 + 12 O 2 → 3 SiO 2 + 6 CO 2 + 9 H 2 O. Strong base degrades siloxane group, often affording siloxide salts: ((CH 3) 3 Si) 2 O + 2 NaOH → 2 (CH 3) 3 SiONa + H 2 O
Silicon dioxide (SiO 2) is a common fundamental constituent of glass. Fused quartz is a glass made from chemically pure silica. [ 68 ] It has very low thermal expansion and excellent resistance to thermal shock , being able to survive immersion in water while red hot, resists high temperatures (1000–1500 °C) and chemical weathering, and is ...
Structure of the orthosilicate anion SiO 4− 4. A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula [SiO (4-2x)− 4−x] n, where 0 ≤ x < 2. The family includes orthosilicate SiO 4− 4 (x = 0), metasilicate SiO 2− 3 (x = 1), and pyrosilicate Si 2 O 6− 7 (x = 0.5 ...
Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas or vacuum.