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Structure of Metals and Alloys

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A metal is a lattice of cations bathed in a sea of delocalized electrons shared by all of them. The electrons are not tied to any one atom; they move freely. That single picture explains why metals conduct electricity and heat, why they are malleable and ductile, and why they are lustrous. Alloys mix in other atoms and change these properties.

UNIT 2 TOPIC 2.4 • STRUCTURE OF METALS AND ALLOYS SEA OF ELECTRONS A metal is a lattice of positive cations immersed in a shared “sea” of mobile, delocalized valence electrons. METALLIC BONDING lattice of cations in an electron sea + + + + + + + + + + + + + metal cation (fixed lattice site) delocalized e⁻ (mobile, shared) Cations bond by mutual attraction to the same sea. Mobile e⁻ → electrical & thermal CONDUCTIVITY MALLEABLE & DUCTILE why metals deform without shattering + + + + + + + + + + + + force Cation layers SLIDE past one another when a force is applied. The electron sea flows with them and keeps the metal bonded — no like-charge repulsion as in brittle ionic solids. MALLEABLE hammered into sheets DUCTILE drawn into wires ALLOYS a metal blended with other elements — new atoms disrupt the lattice, changing hardness & properties SUBSTITUTIONAL Host atoms are replaced by atoms of SIMILAR size. e.g. brass (Cu + Zn), bronze (Cu + Sn) INTERSTITIAL SMALLER atoms fit into the spaces BETWEEN host atoms. e.g. steel (Fe + C) carbon locks layers → harder CED ANCHOR 2.4.A Metallic bonding is modeled as cations in a sea of delocalized electrons; this explains conductivity, malleability, and ductility. Alloys are substitutional or interstitial mixtures of a metal with other elements. Al 13 Fe 26 Cu 29 Au 79 four familiar metals: Al, Fe, Cu, Au AP Chemistry · Unit 2 · Compound Structure & Properties
Metallic bonding: fixed cations in a sea of delocalized electrons. Because the electrons are mobile and shared by all the cations, metals conduct, and because the cations can slide past one another without breaking the bond, metals are malleable and ductile.
Sea of Electrons · Open the sandbox →

The traps invert the model: reading malleability as a sign of weak bonding (the bonding is strong; the cations just slide without snapping it), imagining the electrons are localized on individual atoms, and treating alloying as an inert physical mix rather than something that genuinely alters strength and hardness. The delocalized sea is what ties every property together.

The work

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Lesson
Metallic Bonding ›

The electron-sea model explains conductivity, malleability, and luster in one picture, and shows why alloys behave differently. The lesson reasons each property from delocalization, then closes with a ten-scenario check.

Skill check · 10 scenarios
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Diagnostic
10-item topic check ›

Ten items spanning the three Topic 2.4 misconceptions: malleability read as weak bonding, metal electrons imagined as localized, and alloying treated as an inert physical mixture.

Not started · 10 items · ~15 min
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Targeted Practice
Drill a single misconception ›

Pick one of the failure modes you missed and drill it on its own. The round is adaptive: two correct in a row clears the misconception and moves you to the next.

Take the diagnostic to identify your misconceptions
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