Difficulty: Easy
Correct Answer: conductors
Explanation:
Introduction / Context:
Electrical classification of materials correlates strongly with valence electron count. Metals with few valence electrons have partially filled bands, allowing electrons to move freely and conduct electricity well.
Given Data / Assumptions:
Concept / Approach:
In metals, the conduction band overlaps the valence band or is partially filled, so electrons require minimal energy to contribute to conduction. This arises naturally when few electrons occupy a broad band. Hence, elements with 1–3 valence electrons (e.g., Na, Mg, Al) are typically good conductors.
Step-by-Step Solution:
Identify valence groups: 1–3 → metallic behavior.Band perspective: partially filled conduction band enables free carriers.Empirical evidence: aluminum wires, magnesium alloys, alkali metals conduct well.Conclusion: such elements are generally conductors.
Verification / Alternative check:
Resistivity tables show low resistivity for these metals compared to semiconductors and insulators.
Why Other Options Are Wrong:
Semiconductors: commonly group IV or compounds with effective four-bond networks.Insulators: typically have filled valence bands and large bandgaps.Neutral: not a material category for conduction.
Common Pitfalls:
Equating valence count alone with behavior without considering crystal structure; however, as a rule of thumb, 1–3 valence electrons correlate with metals.
Final Answer:
conductors
Discussion & Comments