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Summaries · Grade 7 Natural Sciences › Properties of materials
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Properties of materials

The properties of materials, and how boiling point and melting point help identify a substance. Read one part at a time and tap “I know this”. Then test yourself in the quiz.

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Properties

PropertyMeaningUse
MalleableCan be hammered flatGold leaf, aluminium cans
DuctileCan be drawn into wireCopper wire
ElasticStretches and returnsTrampoline mat
Stiff (rigid)Does not bendBricks for walls
StrongHard to break or tearSteel beams in bridges
TransparentLight passes throughGlass windows
High thermal conductivityConducts heat wellStainless steel pots
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Choose the right material

  • Pots of stainless steel: conduct heat and resist rust. Handles of plastic or wood: poor heat conductors.
  • Aluminium for cooldrink cans: light, malleable and does not rust.
  • Rubber is a very good electrical insulator; wires in a circuit must have high electrical conductivity.
Each material in its place: copper, plastic, steel and glass.
Each material in its place: copper, plastic, steel and glass.
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Boiling points identify substances

The boiling point is the temperature where a liquid becomes a gas. Measure it with a thermometer. If you measure an unknown liquid’s boiling point and look it up in a table, you can tell which substance it is. Ice-cream melts quickly on a hot day because it warms up to its melting point.

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Materials and the environment

Making and using materials always affects the environment.

  • Mining destroys habitats and can pollute water.
  • Burning coal for energy pollutes the air and causes acid rain.
  • Making paper means cutting down trees and using lots of water.
  • Plastic does not break down for many years and harms animals on land and in the sea.
  • We help when we reduce, reuse and recycle.
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Remember this and test yourself

Remember this: your summary
  • Brittle: breaks easily. Elastic: stretches and springs back. Flexible: bends without breaking. Stiff: does not bend.
  • Malleable: can be beaten flat (gold leaf). Ductile: can be drawn into wire.
  • Copper: conducts well and makes thin wires; the plastic around it is an insulator.
  • Water boils at 100 °C at sea level.
  • Each pure substance has its own boiling point and melting point: this helps to identify it.

Write these points in your book. Read them again the night before the test.

Memory trick

Malleable = you can mallet it flat. Ductile = you can duct it into a wire.

Flash cards · Tap to turn over

Important words

First say what the word means, then turn the card over.

Test yourself · Part 2

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