Atomic structure of silicon – count of tightly bound (core) electrons In a neutral silicon atom (Z = 14), how many electrons are tightly bound in inner shells (i.e., non-valence/core electrons), as opposed to the 4 valence electrons used in bonding?

Introduction:
Understanding the electronic structure of semiconductors clarifies why specific elements act as donors or acceptors and how many electrons participate in bonding. Silicon is a group IV element with four valence electrons forming covalent bonds in the diamond lattice.

Given Data / Assumptions:

• Silicon atomic number Z = 14.
• Ground-state electron configuration of silicon is considered.
• Valence electrons are those in the outermost shell participating in bonding (4 for silicon).

Concept / Approach:

Silicon’s electron configuration is 1s^2 2s^2 2p^6 3s^2 3p^2. The valence shell is n = 3, with 3s^2 3p^2 totaling 4 valence electrons. The remaining electrons (1s^2 2s^2 2p^6) sum to 10 and are tightly bound core electrons that do not participate directly in bonding within the crystal under normal conditions.

Step-by-Step Solution:

Verification / Alternative check:

Periodic table position (group IV) corroborates 4 valence electrons; spectroscopic data confirm inner shells are fully occupied and tightly bound.

Why Other Options Are Wrong:

14 counts all electrons; 6 or 8 do not match the shell filling; 4 is the number of valence electrons, not core electrons.

Common Pitfalls:

Confusing valence with total electron count; overlooking that 2s and 2p electrons are core for silicon.

Final Answer:

10