大象传媒

Different materials

Different have different , but they may also have some properties in common. The table summarises some of the typical properties of glass and clay ceramics, and metals.

GlassClayMetals
AppearanceTransparentOpaqueShiny
Melting pointHighHighHigh
Malleable or brittleBrittleBrittleMalleable
Ability to conduct electricityPoorPoorGood
Ability to conduct heatPoorPoorGood
Appearance
GlassTransparent
ClayOpaque
MetalsShiny
Melting point
GlassHigh
ClayHigh
MetalsHigh
Malleable or brittle
GlassBrittle
ClayBrittle
MetalsMalleable
Ability to conduct electricity
GlassPoor
ClayPoor
MetalsGood
Ability to conduct heat
GlassPoor
ClayPoor
MetalsGood

Glass ceramics

A shattered window
Figure caption,
Glass shatters when it is hit or dropped

Glass is made by melting sand with other substances (especially metal oxides), then allowing the liquid to cool and solidify. Glass is and , but it is .

Clay ceramics

Clay ceramics include brick, china and porcelain. They are made by heating clay to high temperatures, which causes to form and join together. Clay ceramics are often coated with a glaze, which hardens on heating to form a hard, smooth, and waterproof layer.

A brick wall
Image caption,
Brick is strong in compression 鈥 it resists being squashed

Metals

are and , so they can be bent into shape or made into wires without shattering. Unlike glass and clay ceramics, metals are good electrical .

Polymers

are poor conductors of electricity and heat, but their other properties vary depending upon the particular polymer. For example, they can be transparent or opaque. They are often tough and , but some are hard and brittle.