Metallic solids are solids made of metal cations held together by a "sea" of delocalized valence electrons, giving them high electrical and thermal conductivity, malleability, ductility, and generally high melting points (AP Chem Topic 3.2).
A metallic solid is one of the four solid types AP Chem cares about (ionic, covalent network, molecular, metallic). Picture a lattice of positive metal cations sitting in a shared pool of valence electrons that don't belong to any one atom. That's the electron-sea model, and it explains basically every property the exam asks about.
Because the electrons are delocalized (free to move through the whole solid), metallic solids conduct electricity and heat well in the solid state. Because the bonding is nondirectional, layers of cations can slide past each other without shattering the structure, which makes metals malleable (hammerable into sheets) and ductile (drawable into wires). The strength of the metallic bonding also gives most metals high melting points, though the exact value varies a lot from metal to metal.
Metallic solids live in Unit 3, Topic 3.2 (Properties of Solids) and are a textbook case of learning objective 3.2.A, which asks you to explain macroscopic properties using particulate-level structure and the interactions between particles. That's the whole game here. You see a property like conductivity or malleability, and you have to trace it back to delocalized electrons and nondirectional bonding. Per essential knowledge 3.2.A.2, particulate diagrams (cations in an electron sea) are exactly how the exam expects you to communicate this. If you can sketch and explain that model, you can handle nearly any metallic-solid question Unit 3 throws at you.
Keep studying AP Chemistry Unit 3
Ionic Solids (Unit 3)
Both have charged particles in a lattice and high melting points, but ionic solids only conduct when melted or dissolved because their charge carriers (the ions) are locked in place. In a metal, the charge carriers are electrons, and they're always free to move.
Covalent Network Solids (Unit 3)
Network solids like diamond also have strong bonds throughout the whole structure, but those bonds are directional and electrons are localized. That's why diamond is hard and brittle and doesn't conduct, while a metal bends and conducts.
Substitutional Alloy (Unit 2)
Alloys are metallic solids with mixed atoms. In a substitutional alloy like brass, similar-sized atoms swap into lattice positions. The electron sea sticks around, so alloys still conduct, but the foreign atoms disrupt the sliding layers and often make the alloy harder than the pure metal.
Graphite (Unit 3)
Graphite is the classic trap answer. It conducts electricity because of delocalized electrons, but it's a covalent network solid, not a metal. The lesson is that conductivity comes from mobile charge carriers, not from being metallic.
Metallic solids show up almost entirely as "explain the property" questions. Practice and exam questions repeatedly ask why metallic solids conduct electricity (delocalized electrons carry charge) and why they're malleable (nondirectional bonding lets cation layers slide without breaking the structure). Multiple-choice stems often hand you a mystery solid's properties, like "conducts as a solid, malleable, high melting point," and ask you to classify it among ionic, molecular, network, and metallic. On free-response questions, a one-word answer like "metallic bonds" won't earn the point. You need the full causal chain, naming the delocalized electrons or sliding cation layers and connecting them to the observed property. Drawing or interpreting a particulate diagram of cations in an electron sea is also fair game under 3.2.A.2.
Both are lattices of charged particles with high melting points, so the structures feel similar. The difference is who can move. Metallic solids have mobile delocalized electrons, so they conduct in the solid state and deform without shattering. Ionic solids have fixed ions, so they only conduct when molten or dissolved, and shifting the lattice lines up like charges, which makes them brittle. If a question says "conducts as a solid and is malleable," it's metallic. If it says "conducts only when melted and shatters when struck," it's ionic.
Metallic solids are metal cations held in a lattice by a sea of delocalized valence electrons.
Delocalized electrons are the reason metals conduct electricity and heat in the solid state, since the electrons are free to move and carry charge.
Metallic bonding is nondirectional, so layers of cations can slide past each other, making metals malleable and ductile instead of brittle.
Metals conduct as solids while ionic compounds only conduct when molten or dissolved, because metals have mobile electrons and ionic solids have locked-in ions.
Alloys are metallic solids made of more than one element, and mixing atom sizes disrupts layer sliding, which often makes alloys harder than pure metals.
On the exam, always explain metallic properties with the particulate-level cause (delocalized electrons, sliding cation layers), not just the phrase "metallic bonds."
A metallic solid is a solid made of metal cations arranged in a lattice and held together by delocalized valence electrons (the electron-sea model). This structure gives metals high conductivity, malleability, ductility, and generally high melting points.
Their valence electrons are delocalized, meaning they aren't attached to any single atom and can flow freely through the solid. Moving charge is exactly what an electric current is, so metals conduct even in the solid state.
No, not all of them. Melting points correlate with bonding strength but vary widely, and mercury is famously liquid at room temperature. The CED itself (3.2.A.1) notes melting point trends are more subtle than boiling point trends, so say "generally high" rather than "always high."
A metallic solid has mobile delocalized electrons, so it conducts as a solid and bends when struck. An ionic solid's ions are fixed in the lattice, so it only conducts when molten or dissolved and shatters when deformed because like charges get pushed next to each other.
No. Graphite is a covalent network solid that happens to have delocalized electrons within its layers, which is why it conducts. The exam loves this distinction because it tests whether you tie conductivity to mobile electrons rather than to the metallic label.