Metals as conductors — AQA GCSE Chemistry
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Metals as conductors explained
Metals as conductors covers 2 specification points, including Metals are good conductors of electricity… and Metals are good conductors of thermal energy….
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Open a point below for its explanation and revision guidance.
Metals are good conductors of electricity because the delocalised electrons in the metal carry electrical charge through the metal.
Metallic bonding produces a giant lattice of positive metal ions surrounded by delocalised electrons. These delocalised electrons are not attached to any particular ion and are free to move throughout the structure. When a potential difference is applied across a metal, for example by connecting it to a battery in a circuit, the delocalised electrons drift towards the positive terminal. Because electrons carry negative charge, this movement of charge is an electric current. The more freely the electrons can move, the better the metal conducts. This explains why metals such as copper are used for electrical wiring, while materials without delocalised electrons, such as plastics, do not conduct. The same model also helps explain why metals conduct thermal energy.
Metals are good conductors of thermal energy because energy is transferred by the delocalised electrons.
In a metal, the giant lattice contains positive metal ions and delocalised electrons. The delocalised electrons are free to move throughout the structure. When one part of a metal is heated, the electrons in that region gain kinetic energy. Because they are mobile, these electrons move quickly through the metal and transfer energy to other parts of the lattice by collisions and interactions with ions and other electrons. This allows thermal energy to pass rapidly through the metal. The same delocalised electrons are responsible for electrical conduction, which is why metals are good conductors of both electricity and thermal energy. For example, copper and aluminium are used in cooking pans and heat exchangers because they conduct thermal energy efficiently.
Your focus
- Identify delocalised electrons as the mobile charge carriers in metals.
- Explain how the movement of delocalised electrons produces an electric current.
- Relate the presence of delocalised electrons to the good electrical conductivity of metals.
Show all 6 objectives
- Identify delocalised electrons as the particles responsible for thermal conduction in metals.
- Explain how moving delocalised electrons transfer energy through a metal.
- Relate the mobility of delocalised electrons to the good thermal conductivity of metals.
Metals as conductors exam tips
Marking Points
- Metals contain delocalised electrons that are free to move through the giant metallic lattice.
- The delocalised electrons carry electrical charge through the metal.
- When a potential difference is applied, the electrons move and constitute an electric current.
- The presence of mobile charge carriers explains why metals are good conductors of electricity.
- A named example, such as copper used in electrical wiring, can illustrate the property.
- Metals contain delocalised electrons that are free to move through the lattice.
- When heated, the delocalised electrons gain kinetic energy.
- The moving electrons transfer energy through the metal to other regions.
- This transfer of energy by delocalised electrons makes metals good conductors of thermal energy.
- A named example, such as copper or aluminium used in cooking pans, can illustrate the property.
Examiner Tips
- 💡Name the charge carriers explicitly: delocalised electrons.
- 💡Explain that the electrons are free to move through the whole structure, not fixed to one ion.
- 💡Link the movement of electrons to the idea of charge being carried through the metal.
- 💡Refer to delocalised electrons gaining kinetic energy when the metal is heated.
- 💡Explain that the electrons move through the metal and transfer energy to other parts.
- 💡Keep the explanation focused on thermal energy transfer, even though the same electrons also carry electrical charge.
Common Mistakes
- Saying that the positive metal ions carry the current; in metallic conduction it is the delocalised electrons that move and carry charge.
- Stating that electrons are transferred from atom to atom as whole atoms move; the electrons are delocalised and move through the lattice.
- Confusing electrical conduction with thermal conduction; both involve delocalised electrons, but the statement here is specifically about carrying electrical charge.
- Saying that thermal energy is carried only by the metal ions vibrating in place; the delocalised electrons are the key mobile energy carriers.
- Confusing thermal conduction with electrical conduction and describing current flow when the question asks about heating.
- Stating that electrons carry heat as a substance; they transfer energy, not matter.