CBSE · Class 10 · Science · Carbon and its CompoundsExplain the formation of covalent bonds in a molecule of nitrogen ($N2$). Also, explain why carbon forms covalent bonds instead of ionic bonds, discussing the electronic configuration of carbon.

Formation of Covalent Bonds in Nitrogen ($N_2$) Molecule

• Atomic Number and Configuration: The atomic number of nitrogen is 7, and its electronic configuration is 2, 5. It requires 3 more electrons to achieve a stable noble gas configuration (octet).
• Sharing of Electrons: To satisfy the octet rule, two nitrogen atoms share three pairs of electrons between them. This results in the formation of a triple covalent bond between the two nitrogen atoms, represented as $N \equiv N$.
• Stability: This sharing allows both atoms to attain a stable octet, forming a very strong and stable diatomic molecule.

Why Carbon Forms Covalent Bonds

• Electronic Configuration of Carbon: Carbon has an atomic number of 6. Its electronic configuration is 2, 4. It has 4 valence electrons in its outermost shell.
• Impracticability of Ionic Bond Formation ($C^{4-}$ or $C^{4+}$):
  • Gaining 4 electrons ($C^{4-}$) $\rightarrow$ If carbon were to gain 4 electrons to form $C^{4-}$, it would be difficult for a nucleus with 6 protons to hold onto 10 electrons, leading to severe electrostatic repulsion and instability.
  • Losing 4 electrons ($C^{4+}$) $\rightarrow$ If carbon were to lose 4 electrons to form $C^{4+}$, it would require a tremendous amount of energy to remove four tightly bound electrons, which is energetically unfavorable.
• Conclusion: To overcome these energy barriers, carbon achieves stability by sharing its four valence electrons with other carbon atoms or atoms of other elements (like hydrogen, oxygen, chlorine, nitrogen), thereby forming strong covalent bonds.