Silicon crystal structure — atoms in a crystalline silicon lattice are held together by which specific type of atomic bond that shares valence electrons between neighboring atoms?

Introduction / Context:
Understanding the atomic bonding in semiconductors is essential for grasping how pn junctions, doping, and carrier transport work. Silicon forms a tetrahedral crystal lattice where each atom shares electrons with its neighbors. This question asks you to identify the specific bond type responsible for the structure and electrical behavior of silicon.

Given Data / Assumptions:

• Pure crystalline silicon (intrinsic Si) at room temperature.
• Each silicon atom has four valence electrons.
• We are concerned with the fundamental bonding mechanism in the lattice.

Concept / Approach:
Silicon atoms share pairs of valence electrons with adjacent atoms, forming covalent bonds. In an ideal lattice, each silicon atom makes four covalent bonds in a tetrahedral geometry. These bonds hold the crystal together and set the stage for semiconductor behavior: thermal energy can promote electrons from the valence band to the conduction band, leaving holes in the valence band.

Step-by-Step Solution:

Verification / Alternative check:
Basic semiconductor physics texts depict the silicon diamond-cubic lattice and label each interatomic connection as a covalent bond.

Why Other Options Are Wrong:

• Electrostatic (ionic) bond: Dominant in salts like NaCl, not elemental silicon.
• Metallic bond: Applies to metals with delocalized electrons, not silicon’s directional bonds.
• Hydrogen bond: Relevant to molecular systems like water or polymers, not crystal silicon.

Common Pitfalls:
Confusing ionic or metallic bonding with covalent bonding because all involve electrons—only covalent accurately describes silicon’s lattice.

Final Answer:
covalent bond