CONDUCTIONCONDUCTIONConductors And Insulators

From the list of materials listed, which is the best

insulator and which is the worst insulator? And Why?

1.Air2.Vacuum

3.Glass

24th. Nov. 09

Learning ObjectivesLearning Objectives

1. To know why some 1. To know why some materials are good materials are good

insulators and others are insulators and others are not.not.

2. To know that metals 2. To know that metals are good conductors and are good conductors and

non-metals are poor non-metals are poor conductorsconductors

Key wordsKey wordsConductors, InsulatorsConductors, Insulators

Kinetic EnergyKinetic EnergyElectrons, AtomsElectrons, Atoms

BondsBonds

Investigating Investigating Conductivity Using Conductivity Using different Materials different Materials

(Metals and Non-metals) (Metals and Non-metals) page 232page 232

Bunsen Flame (Teacher Demonstration)

Recap States Recap States of Matterof Matter

Liquid-Solid and GasesDraw the particle arrangement in

each state of matter (S-L-G)Using your diagram explain why

gases are not good conductors of heat.

Particle Particle arrangement in S-L-arrangement in S-L-

GG

Solid Liquid Gas

What is the What is the difference in difference in

particle particle arrangement in arrangement in metals and non-metals and non-

metals?metals?

ConductionConduction

As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on

and so on, the vibrations are passed along the metal and so is the heat. We call this... Conduction

Particle Particle arrangement in arrangement in

Non-metalsNon-metals

Particles Particles arrangement in arrangement in

MetalsMetals

Metals are differentMetals are different

The outer _______ for metal atoms drift, and are free to move.

When the metal is heated, this ‘Sea of electrons’ gain _____ energy and transfer it throughout the metal.Insulators, such as ___ and ____, do

not have this ‘Sea of electrons’ which is why they do not conduct heat as well as metals.

electrons

kinetic

woodplastic

Conduction in Conduction in MetalsMetals

All metals are good conductors of electricity. For a similar reason, they are also good conductors of heat.

In metals, not only do the atoms vibrate more when heated, but the free electrons charge around more as well. These transfer the energy much faster than just vibrations in bonds.

Conduction in Non-MetalsConduction in Non-Metals

Every atom is physically bonded to each other in some way. If heat energy is supplied to one part of a solid, the atoms vibrate faster.

As they vibrate more, the bonds between atoms are shaken more. This passes vibrations on to the next atom, and so on:

Eventually the energy spreads throughout the solid. The overall temperature has increased.

Insulator are the Insulator are the opposite of opposite of

conductors. True conductors. True or False? Why?or False? Why?

(use traffic light to assess)(use traffic light to assess)

INSULATORS

Particle arrangement in Particle arrangement in Metals and Non-metalsMetals and Non-metals

Ask a volunteer to read Conduction in Metals

On page 233

Copy key point and answer Q1, Q2 and 3

Testing sheets of Testing sheets of materials as insulators materials as insulators

page 233page 2331. Use different materials to insulate identical

cans (or beakers) of hot water.2. The volume of water and its temperature at

the start should be the same.3. Use a thermometer to measure the water

temperature after the same time.

The result should tell you which insulator was best.

ResultsResultsMaterials Starting

temperature (degree Celsius).

Temperature after 300 s (degree Celsius)

Paper 40 32Felt 40 361. Which material was the best thermal insulator?2. Which variable shown in the table was controlled to make this a fair test.

PlenaryPlenaryWhat happen when you touch a metal?

And why.