Lesson focus: conductionHow heat passes through a solid, as particles vibrate and pass energy on to their neighbours. transfers energy through particle interactions, with mobile electrons making metals especially effective conductors.
Use particle models to explain conduction and compare materials from evidence.
Build on earlier learning
Melting and freezingThe particle model now explains how energy transfers through solids.
Practical
Comparing conductors
- Fix a drawing pin with wax along rods of different metals.
- Heat the end of each rod equally.
- Time how long each pin takes to fall.
Record: A table ranking the metals as conductors.
Safety: Use a heatproof mat and let the rods cool before touching.
Comparing conductors
Each rod is heated at one end. A wax-fixed pin drops when heat reaches it. Move the time slider.
Illustrative times. The better the conductor, the sooner the pin drops.
You will be successful when you can…
- Describe conduction.
- Explain lattice vibration.
- Explain metal conduction.
- Interpret cooling or conduction evidence.
Words that carry the science
- conduction
- Energy transfer through particle interactions without bulk movement of the material.
- thermal conductor
- A material through which energy transfers readily by conduction.
- thermal insulator
- A material that reduces the rate of energy transfer by conduction.
- lattice
- A regular arrangement of particles in a solid.
- free electron
- An electron able to move through a metal structure.
Neighbouring particles transfer energy
01Neighbouring particles transfer energy
In a solid, particles vibrate about fixed positions. Near a hot region they have greater average kinetic energy and interact with neighbouring particles, transferring energy through the latticeA regular repeating pattern of particles in a solid, like oranges stacked in a box..
The particles do not travel from the hot end to the cold end. Energy transfers through their interactions.
02Metals have an additional mechanism
Metals contain mobile free electronAn electron that can move freely through a metal, carrying heat and electricity.. They gain energy in hotter regions, move through the structure and transfer energy in collisions.
This electronic contribution usually makes metals better thermal conductorA material that lets heat pass through it easily, like metal. than wood, plastic or trapped air.
03Insulators slow the rate
Insulators do not stop all transfer. They reduce its rate, often by lacking mobile electrons or by trapping air in small pockets that limit conduction and convection.
A fair conductivity comparison controls material length, thickness, starting temperature and contact with the energy source.
Choose a saucepan design
Select materials for the pan base and handle.
- The base should transfer energy rapidly into food.
- A metal base provides strong conduction through electrons and lattice interactions.
- The handle should reduce transfer to the hand.
- Use a low-conductivity material and sufficient length, while accounting for safe temperature limits.
How to make the reasoning visible: Different parts use different materials because their intended energy-transfer rates differ.
Conduction
The times show how quickly wax melts at equal distances along equal rods.
| Material | Time / s | Rod dimensions | Inference |
|---|---|---|---|
| copper | 18 | same | very good conductor |
| aluminium | 25 | same | good conductor |
| steel | 74 | same | slower conductor |
| glass | >180 | same | poor conductor |
Rank the materials by conduction rate.
Why must rod dimensions be equal?
Check your understanding
Answer from memory, then check against the suggested answer.
What is conduction?
Why do metals conduct well?
Do insulators stop transfer?
Why does a metal bench feel colder than wood at the same temperature?
Why does trapped air insulate better than a large moving air space?
Exam Question Practice
Exam Question Practice
Mark points shown after marking
One end of a metal spoon is put in hot water. The handle gets hot.
Explain how energy is transferred along the spoon by conduction.
(4)Does the metal itself move along the spoon?
(1)Total for this question: 5 marks
Command word: For explainA command word: say how or why something happens, giving reasons with words like "because" or "so"., name both conduction mechanisms in a metal and state the transfer direction.