Which of the following anions is present in the chain structure of silicates?
Which of the following anions is present in the chain structure of silicates?
$\left(\mathrm{Si}_2 \mathrm{O}_5^{2-}\right)_n$
$\left(\mathrm{SiO}_3^{2-}\right)_n$
$\mathrm{SiO}_4^{4-}$
$\mathrm{Si}_2 \mathrm{O}_7^{6-}$
Solution
In silicates, two oxygen atoms per $\mathrm{SiO}_4$ tetrahedron are shared giving polymeric anion chains.
When each tetetrahedron \(\left(\mathrm{SiO}_4^{4-}\right)\) shares two O atoms, infinite chains are formed. The formula of these extended anions approximates to \(\left(\mathrm{SiO}_3\right)_n^{2 n-}\) or \(\left(\mathrm{SiO}_3^{2-}\right)_n . \mathrm{SiO}_4^{4-}\) anion is present in orthosilicates. \(\mathrm{Si}_2 \mathrm{O}_7^{6-}\) anion is present in pyrosilicates, while \(\left(\mathrm{Si}_2 \mathrm{O}_5^{2-}\right)_n\) anion is present in double-chain silicates as well as in sheet silicates.
Structure of silicate:
