This lesson completes the bonding sequence by introducing the Stage 5 metallic bonding model and then comparing metallic, ionic and covalent substances. The goal is not to memorise three separate lists, but to use bonding as evidence for real material decisions.
Use the PDF for classwork, homework or revision. It includes key ideas, activities, questions, an extend task and success-criteria proof.
Write your best idea before you read the lesson. Focus on what must be different inside the material.
Focus on what happens when layers of particles try to move past each other in metals versus ionic crystals.
Students should not treat metals as “just atoms packed together”. The key Stage 5 model is positive ions in a structure with delocalised electrons that can move.
In a metal, the outer electrons are not tied to one single atom in the same way as a simple covalent molecule. A useful Stage 5 model is a lattice of positive metal ions surrounded by delocalised electrons. The attraction between these positive ions and the moving electrons is called metallic bonding.
Because the delocalised electrons can move, metals can often conduct electricity as solids. Because layers of metal ions can shift while the bonding model still holds, metals are often malleable and ductile rather than brittle like many ionic crystals. Many metals also have relatively high melting points, though this can vary between different metals and alloys.
This is the main synthesis point of the bonding block. Students should now be able to compare three models and connect each one to observable material behaviour.
| Material type | Bonding model | Common properties | Use logic |
|---|---|---|---|
| Ionic | Oppositely charged ions attract in a lattice | Often high melting point, brittle, conducts when molten or dissolved | Useful where ionic solutions, heat resistance or specific salt properties matter |
| Covalent | Atoms share electrons, often forming molecules | Many simple molecular substances have low melting/boiling points and poor conductivity | Useful where molecular behaviour suits the task, such as gases, liquids or solvent use |
| Metallic | Positive ions attracted to delocalised electrons | Often conductive, malleable, ductile, often strong | Useful for wires, structures and tools where shaping and conductivity matter |
Suppose you need a material for electrical wiring. A metallic material is usually more suitable than an ionic crystal or a simple molecular substance because conductivity and ductility both matter. Suppose you need a gas in a fire extinguisher: a simple molecular substance such as carbon dioxide makes more sense than a metal. Suppose you need a dissolved substance that conducts in water: an ionic compound may be more suitable.
This is exactly what the Stage 5 materials outcome is asking students to do: assess uses of materials based on their physical and chemical properties, with structure giving deeper explanatory power.
Wrong: Metals conduct electricity because they have ions that can move.
Right: Metals conduct because they have delocalised electrons that can move through the structure, not because of moving ions.
Wrong: Metallic bonding is the same as ionic bonding but with metal atoms.
Right: Metallic bonding is a distinct model: positive metal ions surrounded by delocalised electrons. Ionic bonding is attraction between positive and negative ions from different elements.
Right: Not all metals are magnetic. Magnetic properties depend on the specific metal and its structure, not on metallic bonding itself.
Right: Many ionic substances are brittle, not malleable. If layers shift, like charges can line up and repel, causing the crystal to crack.
Drag each property into the correct bonding type: Ionic, Covalent or Metallic.
Metallic bonding is the attraction between positive metal ions and delocalised electrons in a metal.
Metals are often conductive, malleable and ductile because of their bonding and structure.
Ionic, covalent and metallic substances have different bonding models, so they often show different property patterns.
The best material choice is justified by linking bonding, properties and the needs of the job.
Match each description to ionic, covalent or metallic, then explain why.
a. Conducts electricity as a solid and can be drawn into wires
b. Conducts when molten but is brittle as a solid
c. Made of neutral molecules and often has a low boiling point
Choose the best material type for each task and justify it using structure and property language.
a. Electrical wiring
b. Carbonated drink gas
c. Dissolved substance for an electrolyte solution
Claim: State which material type is best for each task.
Evidence: Name one property that matches the task requirement.
Reasoning: Explain how the bonding model helps explain that property and why the material type is suitable.
1. Which statement best describes metallic bonding at Stage 5 level?
2. Why do many metals conduct electricity as solids?
3. Which material type is usually the best match for making electrical wires?
4. Which comparison is correct?
5. Which answer best shows proper Stage 5 materials reasoning?
Explain metallic bonding using the terms positive ions and delocalised electrons. 1 mark for mentioning positive metal ions. 1 mark for mentioning delocalised electrons. 1 mark for describing the attraction between them.
Why is a metallic material usually more suitable for electrical wiring than an ionic solid? 1 mark for stating metals conduct as solids. 1 mark for linking conductivity to delocalised electrons. 1 mark for stating ionic solids do not conduct. 1 mark for explaining that ions are fixed in ionic solids.
Compare one metallic property with one ionic or covalent property and explain how each affects material use. 1 mark for identifying one metallic property. 1 mark for linking it to use. 1 mark for identifying one ionic or covalent property. 1 mark for linking it to use.
Return to the opening question. Can you now explain why metals conduct as solids and how that differs from ionic and covalent substances?
1: B. Metallic bonding is the attraction between positive metal ions and delocalised electrons.
2: D. Mobile delocalised electrons help metals conduct electricity as solids.
3: A. Metallic materials are usually suitable for wires because they conduct and are ductile.
4: C. That comparison correctly matches metallic and ionic property patterns.
5: B. This answer links structure, property and use properly.
Sample answer: Metallic bonding is the attraction between positive metal ions and delocalised electrons. The structure contains a lattice of metal ions and electrons that can move through the structure. This helps explain common metallic properties such as conductivity.
1 mark for mentioning positive metal ions. 1 mark for mentioning delocalised electrons. 1 mark for describing the attraction between them.
Sample answer: A metallic material is better because it can conduct electricity as a solid and can often be drawn into wires. This links to metallic bonding because delocalised electrons can move and the structure is often ductile. An ionic solid is less suitable because its ions are fixed in place in the solid state and the solid is often brittle.
1 mark for stating metals conduct as solids. 1 mark for linking conductivity to delocalised electrons. 1 mark for stating ionic solids do not conduct. 1 mark for explaining that ions are fixed in ionic solids.
Sample answer: A metallic property is conductivity, which affects use by making metals useful for wiring. A comparison property could be the brittleness of many ionic solids, which affects use by making them less suitable where flexibility or shaping is needed. Good material choices depend on matching the property pattern to the job.
1 mark for identifying one metallic property. 1 mark for linking it to use. 1 mark for identifying one ionic or covalent property. 1 mark for linking it to use.
Metallic bonding uses a model of positive metal ions and delocalised electrons.
Conductivity, malleability and ductility can be explained using metallic structure.
Ionic, covalent and metallic substances differ because their bonding and structure differ.
Next is Checkpoint 2, covering the full bonding block from Lessons 06-10.
The Bond Baron controls ionic, covalent and metallic bonding! Answer L6–10 questions to break the bond — theirs, not yours.