Silicon is present in the sun and stars and is a principal component of a class of meteorites known as aerolites. Silicon makes up 25.7% of the earth's crust by weight, and is the second most abundant element, exceeded only by oxygen. It is found largely as silicon oxides such as sand (silica), quartz, rock crystal, amethyst, agate, flint, jasper and opal. Silicon is found also in minerals such as asbestos, feldspar, clay and mica.
Silicon is important in plant and animal life. Diatoms in both fresh and salt water extract silica from the water to use as a component of their cell walls. Silicon is an important ingredient in steel. Silicon carbide is one of the most important abrasives. Workers in environments where silicaceous dust is breathed may develop a serious lung disease known as silicosis.
Hydrolysis and condensation of substituted chlorosilanes can be used to produce a very great number of polymeric products, or silicones. These range from liquids to hard, glasslike solids with many useful properties.
Elemental silicon transmits more than 95% of all wavelengths of infrared and and has been used in lasers to produce coherent light at 456 nm.
Discoveror: Jöaut;ns Jacob Berzelius
Date discovered: 1824
Discovered at: Sweden
Meaning of name: From the Latin word "silicis" meaning "flint"
Standard state: solid at 298 K
Colour: dark grey with a bluish tinge
Density of solid at ambient temperature/kg m-3: 2330
Molar volume/cm3: 12.06
Covalent (single bond):
Pauling radius for the ion [Si]-: 384
Valence shell orbital radius maxima (Rmax)
|radius||95.1||115.1||no data||no data|
Both values are quoted on the Pauling scale.
Allred Rochow: 1.74
The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.
melting point: 1687
boiling point: 3173
Enthalpies /kJ mol-1
single bond enthalpies:
Ionization enthalpies /kJ mol-1
This section gives some data for naturally occurring isotopes.
||% natural abundance
|28Si||27.9769271 (7)||92.23 (1)|
|29Si||28.9764949 (7)||4.67 (1)|
|30Si||29.9737707 (7)||3.10 (1)|