Question

The organic solvent acetone has the molecular formula \[{{(\text{C}{{\text{H}}_{3}}\text{)}}_{2}}\text{CO}\]. The silicon analogue, a thermally stable lubricant, is a polymer, \[{{\left( {{(\text{C}{{\text{H}}_{3}}\text{)}}_{2}}\text{SiO} \right)}_{\text{n}}}\]. Account for the difference in structure.

Answer 1

Hint: Those elements which are present in the similar chemical properties as the outermost valence electron is the same in all the elements of the same group. Also, elements of the same group have similar physical properties and have the same bonding but the position of an atom is different.

Complete step by step Answer:
-In the given question, we have to tell why there is a difference in the structure of the acetone and silicon.
-As we know that elements which are present in the same group have the same number of valence electrons due to which they have the same chemical and physical properties.
-The carbon and silicon both are present in group 14 and have electronic configuration of \[\text{1}{{\text{s}}^{2}}\text{ 2}{{\text{s}}^{2}}\text{ 2}{{\text{p}}^{2}}\text{ and 1}{{\text{s}}^{2}}\text{ 2}{{\text{s}}^{2}}\text{ 2}{{\text{p}}^{6}}\text{ 3}{{\text{s}}^{2}}\text{ 3}{{\text{p}}^{2}}\]
-Now, due to the presence of the same valence electrons, both carbon and silicon have the same ability to make 4 bond pairs.
-In acetone, carbon makes two bonds with oxygen and two bonds with the carbon similarly silicon makes two bonds with oxygen and two bonds with carbon.
-But when the silicon structure undergoes a polymerization reaction it forms polymethyl siloxane.
-So, according to the given structures the acetone is the single unit but the silicon forms a long chain by combining about 100 units.
-That's why there is a difference in the structure of both elements.


Note: Poly Methyl siloxane is a polymer which is made by the repetition of the monomer dimethyldichlorosilane. It is also known as an anti-foaming agent. PDMS or Poly Methyl siloxane is used as an emulsifier in the food.