302by four oxygen atoms that bridge to other silicon atoms to form a three dimensional
lattice. Silica is soluble in water at high temperatures forming a range of
compounds called monosilicic acid, Si(OH) 4.
Under the right conditions monosilicic acid readily polymerizes to form more
complex silicic acids, ranging from the simplest condensate, disilicic acid (H 6 Si 2 O 7 )
to linear, ribbon, layer and lattice structures which form the basis of the many
silicate minerals and are called polysilicic acids {Six(OH)4–2x}n.
With oxides of other elements the high temperature reaction of silicon dioxide can
give a wide range of glasses with various properties. Examples include soda lime
glass, borosilicate glass and lead crystal glass.
Silicon sulfide, SiS 2 is a polymeric solid (unlike its carbon analogue the liquid CS 2 ).
Silicon forms a nitride, Si 3 N 4 which is a ceramic. Silatranes, a group of tricyclic
compounds containing five-coordinate silicon, may have physiological properties.
Many transition metal complexes containing a metal-silicon bond are now known,
which include complexes containing SiHnX3−n ligands, SiX 3 ligands, and Si(OR) 3
ligands.
Silicones are large group of polymeric compounds with an (Si-O-Si) backbone. An
example is the silicone oil PDMS (polydimethylsiloxane). These polymers can be
crosslinked to produce resins and elastomers.
Many organosilicon compounds are known which contain a silicon-carbon single
bond. Many of these are based on a central tetrahedral silicon atom, and some are
optically active when central chirality exists. Long chain polymers containing a
silicon backbone are known, such as polydimethysilylene (SiMe 2 )n.
Polycarbosilane, [(SiMe 2 ) 2 CH 2 ]n with a backbone containing a repeating -Si-Si-C
unit, is a precursor in the production of silicon carbide fibers.History
Attention was first drawn to quartz as the possible oxide of a fundamental chemical
element by Antoine Lavoisier, in 1787. In 1811, Gay-Lussac and Thénard are thought to
have prepared impure amorphous silicon, through the heating of recently isolated
potassium metal with silicon tetrafluoride, but they did not purify and characterize the
product, nor identify it as a new element.
In 1824, Berzelius prepared amorphous silicon using approximately the same method as
Gay-Lussac (potassium metal and potassium fluorosilicate), but purifying the product to a
brown powder by repeatedly washing it. He named the product silicium from the Latin
silex, silicis for flint, flints, and adding the "-ium" ending because he believed it was a
metal.
As a result, he is usually given credit for the element's discovery. Silicon was given its
present name in 1831 by Scottish chemist Thomas Thomson. He retained part of
Berzelius's name but added "-on" because he believed silicon a nonmetal more similar to
boron and carbon.
Silicon in its more common crystalline form was not prepared until 31 years later, by
Deville. By electrolyzing impure sodium-aluminum chloride containing approximately 10%
silicon, he was able to obtain a slightly impure allotrope of silicon in 1854. Later, more
cost-effective methods have been developed to isolate silicon in several allotrope forms,
the most recent being silicene.