Electrical conductivity trends in Period 3 metals Steps: - Identify Period 3 elements: Na, Mg, Al (metals with high conductivity), Si (semiconductor, low), P, S, Cl, Ar (non-metals, very low or zero). - Recall conductivity depends on delocalized electrons in metals; more valence electrons increase charge carriers. - Order for metals: Al (3 valence e⁻) > Mg (2) > Na (1), based on measured conductivities (Al ≈ 3.5 × 10⁷ S/m, Mg ≈ 2.3 × 10⁷, Na ≈ 2.1 × 10⁷). - Compare options: Select the one matching this metallic trend without including non-conductors. Why B is correct: - B shows Al > Mg > Na, aligning with the trend of increasing delocalized electrons from group 1 to 3 per metallic bonding theory. Why the others are wrong: - A reverses the order (Na > Mg > Al), ignoring higher electron density in Al. - C includes Si as comparable to metals, but Si has low conductivity as a semiconductor. - D assigns high conductivity to non-metals like P > S > Cl, violating insulator properties of non-metals. Final answer: …