PART - 1 CH - 4 Carbon and Its Compounds — Science STD 10 — Question
Gujarat BoardEnglish MediumSTD 10SciencePART - 1 CH - 4 Carbon and Its Compounds4 Marks
Question
Explain the tetravalency of carbon.
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Answer
The atomic number of carbon is 6. $\rightarrow$ Hence, the electronic configuration of carbon is written as : $\begin{array}{rr}{ }_6\text {C} :\text {K} &\text {L} \\ 2 & 4\end{array}$ $\rightarrow$ Thus, carbon has four electrons in its outermost shell. $\rightarrow$ The reactivity of any element depends upon its tendency to attain a completely filled outermost shell, that is, to attain noble gas configuration. $\rightarrow$ Elements forming ionic compounds achieve this by either gaining or losing electrons from their outermost shell. $\rightarrow$ Carbon atom needs to gain or lose four electrons to attain noble gas configuration (complete octet). $\rightarrow$ If carbon atom has to gain or lose electrons, then, - (1) It could gain four electrons forming $\text C ^{4-}$ anion. But, it would be difficult for the nucleus with six protons to hold on ten electrons, that is, four extra electrons, which is unstable. (2) It could lose four electrons forming $\text C ^{4+}$ cation. But it would require a large amount of energy to remove four electrons leaving behind a carbon cation with six protons in its nucleus holding on just two electrons which is unstable. $\rightarrow$ In short, carbon atom cannot combine by forming electrovalent or ionic bond. $\rightarrow$ Hence, carbon, by sharing its valence electrons with other atoms of carbon or with atoms of other elements forms a molecule. $\rightarrow$ A bond formed by sharing of electrons of outermost shell (valence electrons) of two atoms is called covalent bond. $\rightarrow$ The shared electrons belong to the outermost shells of both the atoms and lead to both atoms attaining the noble gas configuration.
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