3.2Chapter 3: Metals and Non-Metals

Comparing conductors — Alhussan Chemistry - Stage 7 Revision Notes & Topical Questions

5 min read 9 parts Lesson 2 of 7 3 quizzes

📚 Alhussan Chemistry - Stage 7 Hub / Topical Revision

0%read

Lesson summary

3.2 Comparing conductors — Thermal and Electrical Conductivity — Alhussan International Academy — Chemistry (Stages 7–9) notes: Plan and evaluate a fair-test investigation to compare how well metals conduct thermal energy and electricity.Conductor = a material that allows energy …

Explanation
Scientific question
Controlling variables
Prediction
Accurate data
Reliable data

Section 1 of 9Conductors and insulators

Conductor

Conductor a material that allows energy or charge to move through it easily.

Thermal conductors transfer thermal energy well and electrical conductors let an electric current flow.

Insulator

Insulator a material that does not conduct well.

Pattern

Pattern most metals are good thermal and electrical conductors and most non-metals are poor conductors.
Graphite, a form of carbon, is a non-metal that conducts electricity.
Silver is the best conductor, followed by copper, which is why copper is used in electrical wires.

Explanation

Explanation metals contain delocalised (free) electrons that carry charge and pass on energy quickly.

Section 2 of 9Why heat sinks matter

Heat sink

Heat sink a metal part in a computer that transfers thermal energy away from the processor and stops it getting too hot.

Question

Question some computers have aluminium heat sinks and others copper, so which metal is better, and why are iron and zinc not used?

Section 3 of 9Asking a scientific question and planning

Scientific question

Scientific question a question that can be answered using evidence.

"Which heat sink is better?" is not scientific, but "Which conducts thermal energy quickest — aluminium, copper, iron or zinc?" is.

Apparatus

Apparatus four metal strips with a drawing pin attached to each by wax, heated at the same end by one candle.
As thermal energy travels along the strip the wax melts and the pin drops off.
The time from lighting the candle to each pin falling is measured.

Fair test

Fair test only one variable changes.

Type of variable	Meaning	In this investigation
Independent	The quantity changed	Type of metal
Dependent	The quantity that changes in response	Time for pin to fall off
Control	Variables kept the same	Size of metal strip, amount of wax, amount of heat

Controlling variables

Controlling variables measure the strips to check their size and weigh the same mass of wax.
The same candle heats all four metals at once, so the thermal energy supplied is equal.

Safety

Safety take care when lighting the candle and let hot metals cool before touching them.

Section 4 of 9Prediction, accuracy and reliability

Prediction

Prediction data books show that copper conducts best, followed by aluminium,
- then zinc, with iron the lowest,
- so the pin on the copper strip should drop first.

Accurate data

Accurate data data close to the true value, helped by starting the timer when the candle is lit and noting the time each pin falls.

Reliable data

Reliable data data obtained by making enough measurements, so repeat the whole experiment three times and calculate means.

Conclusion

Conclusion a bar chart shows the pin drops off copper first,
so copper conducts thermal energy best,
which explains why heat sinks are made of copper or aluminium and not iron or zinc.

Section 5 of 9Investigating electrical conductivity

Investigating electrical conductivity

Build a simple circuit with a cell, a lamp or ammeter and a gap where materials can be connected.

Connect copper, iron, aluminium, graphite, plastic and wood in turn.

A brighter lamp or larger current shows a better conductor.

Results
- metals and graphite complete the circuit, while plastic and wood do not.

Section 6 of 9Analysing results

Present results in a table and plot a bar chart, because the metals are categories.

Errors

Errors uneven heating, rods of different thickness and drawing pins of different mass.

Conclusion

Conclusion state the best conductor, quote the data and explain using free electrons.

Material	Thermal	Electrical
Copper	Very good	Very good
Iron	Good	Good
Plastic	Poor	Poor
Graphite	Moderate	Good

Section 7 of 9Applications of conductors

Copper

Copper it is used in electrical wires and cooking pans because it conducts heat and electricity well and is ductile.

Aluminium

Aluminium it is used in overhead power cables because it conducts well and has a low density.

Plastic

Plastic it coats wires as a safe insulator.

Polystyrene and wool

Polystyrene and wool they trap air and reduce heat loss.

Justifying a choice

Justifying a choice state the property, say why it matters for the use and give the material.

Section 8 of 9Key terms

Term	Meaning
Conductor	A material that lets energy or charge pass through easily.
Insulator	A material that does not let energy or charge pass easily.
Scientific question	A question that can be answered using evidence.
Independent variable	The quantity the investigator changes.
Dependent variable	The quantity measured as it changes.
Control variable	A variable kept the same in a fair test.

Section 9 of 9Exam technique

Saying all metals conduct equally well.

Saying all non-metals are insulators — graphite conducts electricity.

Not controlling variables so the test is unfair.

Describing electrons as used up when they move round a circuit.

Last updated: 18 October 2026