Task
Draw the particle arrangement for a solid, liquid and gas. Each diagram should have a maximum on 9 particles.
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solid liquid gas
Particles that are very close together can transfer heat energy as they vibrate. This type of heat transfer is called conduction.
What type of solids are the best conductors?
Conduction is the method of heat transfer in solids but not liquids and gases. Why?
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Element structure
Na23
Sodium
11Atomic Number – the number of protons and
electrons. (11p and 11e)
Mass Number – the number of protons and neutrons. (11p and 12n)
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Element structure
Na23
Sodium11
p n
The maximum number of electrons in each shell is 2, 8 and 8.
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Metals are good conductors of heat.
The outer electrons of metal atoms are not attached to any particular atom. They are free to move between the atoms – therefore are called FREE ELECTRONS
When a metal is heated, the ions vibrate more and the free electrons gain kinetic energy.
heat
This means that the free electrons move (diffuse) faster and transfer the energy through the metal through collisions with other free electrons and ions in the cooler region.
This makes heat transfer in metals very efficient.
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What about non-conductors?
These are called Insulators. Air is one of the best
Insulators (woolly jumpers)
Insulators have no FREE ELECTRONS.
They do not conduct heat as well as metals. Instead the atoms hold the electrons firmly in place.
Instead thermal energy is transferred through atom vibration instead (less effective).
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heat
ConclusionsMetals conduct heat better than non metals.
Copper is a better conductor than steel.
Wood conducts heat better than glass.
The transfer of heat is faster when the temperature difference is greater.
Remember: We know that metals are good conductors – think of a barbeque, you don’t touch the metal when it is hot!
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InvestigationUse different materials to insulate identical beakers of hot
water.
Control variables – amount of water, starting temperature, type of thermometer, same time period.
Try to explain what is happening in terms of type of heat transfer and particle theory.
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