12th Class Chemistry The p-block Elements-II / p-ब्लॉक तत्व-II Question Bank 11th CBSE Chemistry The P-Block Elements

  • question_answer
    Why does not silicon form an analogue of graphite? Or Why does elemental silicon not form graphite like structure as carbon does. Explain. Or No form of elemental silicon is comparable to graphite.

    Answer:

                    In graphite, carbon is \[s{{p}^{2}}\]-hybridized and each carbon is linked to three other carbon atoms by forming hexagonal rings. Each carbon is now left with one unhybridized p-orbital which undergoes sideways overlap to form three \[p\pi -p\pi \] double bonds. Thus, graphite has two-dimensional sheet like (layered) structure consisting of a number of benzene rings fused together. Silicon, on the other hand, does not form an analogue of carbon because of the following reason: Due to bigger size and smaller electro negativity of Si than C, it does not undergo \[s{{p}^{2}}\]-hybridization and hence it does not form \[p\pi -p\pi \] double bonds needed for graphite like structure. Instead, it prefers to undergo only \[s{{p}^{3}}\]-hybridization and hence silicon has diamond like three-dimensional network structure.


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