C, Si and Ge have same no. of valence electrons. C is an...

C, Si and Ge have same no. of valence electrons. $C$ is an insulator because energy required to take one electron out from
(A) Si is more
(B) $\mathrm{C}$ is more
(C) Ge is more
(D) $\mathrm{C}$ is less

Key Concepts

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom and determine the chemical bonding and physical properties of an element. Even though C, Si, and Ge all have the same number of valence electrons, the way these electrons are held and participate in bonds differ across these elements, affecting their electronic behavior in solids.

Ionization Energy

Ionization energy is the energy required to remove an electron from an atom. In the context of the question, carbon has a higher ionization energy compared to silicon and germanium, meaning it takes more energy to free an electron. This contributes to the insulating nature of carbon, as the electrons are more tightly bound to the nucleus.

Band Theory and Energy Gaps

Band theory explains the allowed and forbidden energy levels in solids. Insulators have a wide energy gap between the valence band and conduction band, meaning that electrons require significant energy input to jump to the conduction band and conduct electricity. The strong covalent bonds in carbon, particularly in diamond, result in a large band gap making it an effective insulator.

Covalent Bonding in Crystalline Solids

In crystalline solids like diamond, atoms are bonded together through covalent bonds, forming a rigid lattice. The nature and strength of these bonds influence the overall electronic properties of the material. In carbon, the strong directional covalent bonds create a structure with a substantial energy barrier for electron excitation, which is key to its insulating behavior.

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