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Difficulty: MediumConductors, Insulators, and Semiconductors

How does the atomic structure of a semiconductor material, such as silicon, determine its electrical behavior compared to a metallic conductor like copper?

  1. Silicon has four valence electrons that form covalent bonds, resulting in moderate conductivity, whereas copper has one loosely held valence electron that easily moves as electrical current.Answer
  2. B
    Silicon has eight tightly bound valence electrons that completely block electron movement, whereas copper has four valence electrons that allow moderate current flow.
  3. C
    Silicon has one valence electron that moves freely across atoms, whereas copper contains five valence electrons that resist electrical potential.
  4. D
    Silicon has two valence electrons that create permanent positive charges, whereas copper has six valence electrons that prevent electron mobility.

Answer

Silicon has four valence electrons that form covalent bonds, resulting in moderate conductivity, whereas copper has one loosely held valence electron that easily moves as electrical current.
Electrical conductivity is determined by the number and binding strength of electrons in an atom's outermost (valence) shell. Metallic conductors like copper contain a single loosely bound valence electron that easily detaches to form electrical current under an electric field. Semiconductor elements like silicon contain four valence electrons that form covalent bonds with neighboring atoms in a crystal lattice, creating an intermediate resistance and conductivity between that of good conductors and non-conducting insulators.

Step-by-Step Solution

1
Analyze the valence electron configuration of conductors and semiconductors.
Good metallic conductors (such as copper, silver, and gold) have 1 to 3 valence electrons in their outermost shell, with copper having 1 loosely bound electron. Pure semiconductors (such as silicon and germanium) have exactly 4 valence electrons.
The number of electrons in the outermost shell dictates how readily electrons can detach and move in response to an electromotive force.
2
Examine how atomic bonding affects conductivity in each material class.
In copper, the single valence electron is loosely held and moves freely throughout the metallic lattice as free electron drift. In silicon, the four valence electrons form covalent bonds with adjacent atoms, creating an energy gap that gives it an intermediate conductivity.
Understanding the atomic mechanism explains why metals conduct readily while semiconductors require added energy or doping to increase charge carrier mobility.

Key Concept

Atomic Valence and Electrical Classification of Materials
Estimated Time:1m 0s
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Topics

Conductors, Insulators, and Semiconductors

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