Semiconductor basics: how many valence electrons does a typical group IV semiconductor atom (e.g., Si or Ge) possess?

Introduction / Context:
Valence electrons determine bonding and electrical properties. Group IV elements like silicon and germanium form the backbone of modern semiconductor devices and integrated circuits.

Given Data / Assumptions:

• Focus on elemental semiconductors Si and Ge (group IV of the periodic table).
• Valence shell electrons define covalent bonding in the crystal lattice.
• Standard crystalline state at room temperature.

Concept / Approach:
Group number approximates valence electrons for main group elements: group IV → four valence electrons. In a diamond-cubic lattice, each atom forms four covalent bonds, sharing its four valence electrons with neighbors.

Step-by-Step Solution:
Identify group: Si, Ge in group IV.Valence count: 4 per atom.Implication: intrinsic semiconductors have filled valence bands and empty conduction bands at 0 K; conductivity arises via thermal excitation or doping.

Verification / Alternative check:
Periodic table cross-check: carbon, silicon, germanium, tin (in relevant allotropes) have four valence electrons.

Why Other Options Are Wrong:
2: typical of group II metals; 8: a full valence shell is not the valence count here; 16: refers to total electrons in multiple shells, not valence.

Common Pitfalls:
Confusing valence electrons with total electrons; mixing compound semiconductors (III–V or II–VI) where valence counts per atom differ.

Final Answer:
4