Question

Write a short note on:
$(i)$ Zeolite
$(ii)$ Silicates
$(iii)$ Silicones

Answer 1

Zeolite, silicones and silicates are compounds of the silicon atom. The element could be traced universally in our world but is not found individually in our environment. Silica and silicates are the most abundant compounds on the earth’s crust.

Complete answer:
$(i)$ Zeolite: Zeolites are microporous, aluminum silicate minerals commonly used as commercial adsorbents and catalysts. Zeolites have small openings of fixed size in them which allows molecules to pass through them easily but larger molecules cannot pass through them; that is why they are called as molecular sieve. Some examples of zeolites are:
$N{a_2}{K_2}CaMg{(Al{O_2})_2}{(Si{O_2})_2}.6{H_2}O$ (Erionite)
$N{a_2}Ca{(Al{O_2})_2}{(Si{O_2})_4}.6{H_2}O$ (Gemelinite)
$(ii)$ Silicates: Silicates is any member of a family of tetrahedral shaped anion consisting of silicon and oxygen, usually with the general formula $[Si{O_{4 - x}}^{(4 - 2x)}]$. It formed about one-quarter of the crust of the Earth. The $Si{O_4}$ tetrahedral units can share oxygen atoms and be linked in a variety of ways, which result in different structures. Examples- nesosilicates are minerals whose structure is made up of silicate tetrahedra. Sorosilicates are minerals consisting of double tetrahedral groups in which one oxygen atom is shared by two tetrahedra.
$(iii)$ Silicones: Silicones are polymers also known as polysiloxanes, are polymers that include any synthetic compound made up of copying units of siloxanes, which is a chain of alternating silicon atoms and oxygen atoms, combined with hydrogen, carbon and sometimes other elements. A general formula for silicones is ${({R_2}SiO)_x}$. Examples of silicones are- poly-dimethylsiloxane.

Note:
Natural zeolites are mostly found in volcanic and sedimentary rocks like Faujasite $(N{a_{56}}{(Al{O_2})_{56}}(Si{O_2})136.250{H_2}O)$ and synthesized zeolites are manufactured by energy-consuming process like Lindea $({[N{a_{12}}{(Al{O_2})_{12}}{(Si{O_2})_{12}}.27{H_2}O]_8})$. Silicones have good thermal stability. Siloxane molecule rotates freely around the silicon-oxygen bond, so even with vinyl, methyl or phenyl groups attached to silicon atoms, the molecule is highly flexible.