Silicon dioxide

Silicon dioxide, also known as silica, is a chemical compound that is an oxide of silicon with the chemical formula SiO₂. It has been known since ancient times. Silica is most commonly found in nature as quartz, as well as in various living organisms. In many parts of the world, silica is the major constituent of sand.

Chemical Structure

Silicon dioxide is formed of two oxygen atoms covalently bonded to a central silicon atom. It is a giant covalent structure, similar to that of diamond. This structure gives silicon dioxide its high melting and boiling points.

Occurrence

Silicon dioxide is most commonly found in nature as quartz, which comprises more than 10% by mass of the earth's crust. Quartz is the only polymorph of silica stable at the Earth's surface. Other forms of silica include coesite, tridymite, and cristobalite, but these are much less common and are only found in certain types of metamorphic rock.

Uses

Silicon dioxide is used in a variety of applications. It is a primary raw material for many ceramics such as earthenware, stoneware, and porcelain. Silica is also used in the production of glass for windows, drinking glasses, beverage bottles, and many other uses. In addition, it is used as a filler in the production of rubber and plastic products, and in the manufacture of cement.

Health Effects

Inhaling fine particles of silica can lead to silicosis, a serious and irreversible lung disease. Silica can also cause lung cancer and has been linked to other diseases, such as tuberculosis, chronic obstructive pulmonary disease, and kidney disease.

See Also

• Silicon
• Quartz
• Silicosis

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