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Carbon and its Compounds — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceCarbon and its Compounds5 Marks
Question
State the reason why carbon can neither form $\text{C}^{4+}$ cations nor $\text{C}^{4-}$ anions, but forms covalent compounds. Also state reasons to explain why covalent compounds:
  1. Are bad conductors of electricity?
  2. Have low melting and boiling points?
✓

Answer

Carbon atoms have 4 electrons in their outermost shell. So needs to gain or lose electrons to attain noble gas configuration.

  • It could gain four electrons forming $\text{C}^{4-}$ anion. But it would be difficult for the nucleus with six protons to hold on to ten electrons.
  • It could lose four electrons forming $\text{C}^{4+}$ cation. But it would require a large amount energy to remove four electrons from its outermost shell.

Because of these reasons, carbon shares its valence electrons to complete its octet with other atoms to from cavalent bonds.

  1. Covalent compounds are bad conductors of electricity because they do not contain ions.
  2. Covalent compounds have usually low melting and boiling points because they are made up of electronically neutral molecules of a covalent compound is very weak. Only a small amount of heat energy is required to break these weak molecular forces, due to which covalent compounds have low melting and boiling points.

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