3. Introduction
Silicates are derivatives of silicic acid
(H4SiO4). They contain tetrahedral
(SiO 4) 4-
anion. In all silicates silicon undergoes
sp3 hybridisation.These involve two
Types of silicoin oxygen bond one is
Terminal –Si-O bond and other is
Bridging –Si-O-Si bond.Silicon will have
four coordination number in silicates
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6. Ortho Silicates
These are simple silicates which contain discrete( SiO 4) 4-
Unit. These are also called silicon tetraoxide anion.
Oxygen atom form coordinate bonds
With associated cations .
For example phenacite (Be2SiO4),
Zircon (ZrSiO4) etc.
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7. Pyrosilicates
PyroSilicates are formed when two tetrahedral( SiO 4) 4-
Unit share a common oxygen.These are either an ionic
Compound that contain( Si 2O 7) 6-
Anion or hexavalent O3Si-O-SiO3.
Group. Pyro Silicates also known as
Disilicates .PyroSilicates occur widely in
Nature as a class of silicate minerals which is known
As sorosilicates .
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8. Thortveitite (Sc2Si2O7).this is primary
Source of Sc.
Other example is hemimorphite
(Zn4(OH)4Si2O7)
hemimorphite
Examples of PyroSilicates
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9. Cyclic Silicates
When two oxygens of each (SiO4)4- unit are share each
Other cyclic or ring silicates are obtained.The primary
Unit cyclic Silicates is(SiO3)3- .There are two types of
cyclic ion (Si3O9)6- ,(Si6O18)12- .
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11. Chain Silicates
These are formed by Sharing of two oxygen atoms of each of
(SiO4)4- units such that a linear chain is formed.
There are two types of chain Silicates.
1.Single chain Silicates They contain (SiO3)n2- chain
Chain And known as pyroxene. Common
Example are spodumene LiAl(SiO3)2.
2. Double chain silicates They contain
(Si 4O11) unit . Double chain formed when two single chain are
linked by sharing of oxygen .these are called amphiboles which
always contain a hydroxy group attached to the metal ion. For
example Tremolite Ca 2Mg5(Si 4O11)2 (OH)2 .
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13. Sheet Silicates
These are formed by sharing
of three oxygen atoms of
Each (SiO 4)4- units .this
Sharing gives an infinite two
Dimensional sheets.sheet
Silicates contain (Si 2O5)n 2n-
Type anion .
-
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14. Examples of sheet silicates
Talc (Mg 3(OH) 3Si 4O10)
Kaolinite (Al 2(OH)4 Si 2O5 ).
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15. Three Dimensional Silicates quartz
When all the four oxygens of (SiO 4)4- units are shared
An infinite three dimensional network is obtained.Since
All the oxygens are shared the silicate is neutral
They have general formula (SiO 2) n .
For example quartz,tridymite
But in some cases Si4+ is replaced
By Al3+ in tetrahedral position in
SiO 2 lattice.for example
Feldpar (KAl Si3O8).
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16. Uses of silicates
1.Silicates are perfect material used to make microchips to
watches .
2. used to make glass and ceramic.
3.Frequently used material in dentistry.
4. Used for tribochemical silication of different surfaces such
as ceramics or alloys
5.Sodium silicates used in silica gel ,textile ,passive Fire
protection.
6. used in soaps and detergents.
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17. Conclusion
Silicates Are most occurring minerals on earth .It is
Very important for technology and everyday life.Silicates
More than any other group of chemical compounds with
Exception of carbon compound exhibit an enormous chemical
And structural variability.
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18. References
1.Modern Approach To Inogranic Chemistry By
Dr. S .P .Jauhar.
2. htpps// en .m. Wikipedia .org
3. https // chem. Liber texts .org
4. https // www. Tulune .edu
5. https//www. Visionlearning .com
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