1. I will need an oven glove to hold which saucepan handle when the contents are hot?

2. Lesson Aims
To be able to explain conduction in terms of the particle model
To explain that in general metals are good conductors.
To describe how trapped air is a good insulator i.e. prevents conduction.

3. What is the particle model?
Lesson Aims:
Questions: What has happened to the kinetic energy of the particles in each model. If the liquid in the glass beaker is at a higher temperature than the beaker, what will happen to the beaker’s temperature? If you put two solids together (each having a different temperature) what will happen in each solid.

4. Conduction Lesson Aims:
If you heat one end of a solid bar, the thermal energy will travel through the solid from the hot region to the cold region.
This is called CONDUCTION

5. Transfer of heat energy along metal bars demonstration

6. Describe what would happen if…
Use these ideas in your answer:
Heat energy Conduction Vibrations Lattice ions Thermal conductivity
Free electrons Metals

7. Order the metals in terms of thermal conductivity (highest to lowest)

8. Conduction in metals Metals are good conductors of heat because:
Metals have atoms inside them and lots of free electrons.
The free electrons can move around and vibrate.
The heat energy is passed on by neighbouring electrons vibrating along the metal.

9. In which example will the yellow end of the metal bar get hot quickest?1 2 3

10. Conduction – compare a metal and a non-metal
If you touch a piece of wood and a piece of copper metal that are both at room temperature (e.g. both at 25°C), which material feels warmer?
The wood feels warmer because it is a poor conductor.
The wood cannot conduct heat away from your hand as quickly as the copper, which is a good conductor.

11. Conduction in non-metals
Non-metals are poor conductors of heat.
In a non-metal, heat energy is only passed on by neighbouring particles vibrating along the non-metal (no free electrons).
This allows a flow of energy from hot to cold.

12. Conduction in liquids 100°C 0°C
Metals are good conductors of heat and non-metals are poor conductors of heat (insulators).
Are liquids good at conducting heat?
Use some gauze to hold an ice cube at the bottom of a tube of water.
100°C
Carefully heat the water at the top of the tube only, until this water is boiling.
0°C
If the liquid is good at conducting, the ice should quickly melt – it doesn’t.
Liquids are poor conductors of heat (i.e. good insulators).

13. Conduction in gases
Liquids are poor conductors of heat (good insulators).
Are gases good at conducting heat?
Carefully hold a safety match 1 cm away from a Bunsen burner flame. (Do not put the match in the flame!)
If a gas is a good conductor, the air between the flame and the match should conduct heat and light the match – it doesn’t.
Gases are poor conductors of heat (i.e. good insulators).

14. Conduction Summary Lesson Aims:
Conduction happens when particles transfer thermal energy through contact.
Metals are GOOD conductors of thermal energy because they have free electrons.
Non-metals are POOR conductors of thermal energy they are called INSULATORS.
Liquids and gases are also poor conductors of thermal energy. Trapped air (gases) are very commonly used as an effective type of insulation.
A vacuum is a perfect insulator for heat transferred by conduction. Why?

15. Conduction Quesitions
Lesson Aims:
Conduction Quesitions
In this example a metal bar at 10oC is in contact with one at 50oC. Draw diagrams for the examples below and show the direction of heat flow.
10oC
50oC
Heat Flow
A in contact with B
A in contact with D
A in contact with C
C in contact with D
For the situation in A describe what happens to the particles in each bar after they have touched.
0oC A
-30oC B
80oC C
200oC D

16. Homework for Friday am
Lesson Aims:
Write a brief explanation (one or two sentences only) of Convection and Radiation. Use the internet to help you but you must use your own words and write down where you got your information.
Come to the next lesson prepared to explain these two examples of heat transfer to the class.
Remember to put the title and date at the start of your work.