Metals and Non-metals
≈ 18 minMetals and non-metals differ in ways you can test in a classroom:
| Property | Most metals | Most non-metals |
|---|---|---|
| appearance | shiny when polished | dull |
| heat | good conductors | poor conductors |
| electricity | good conductors | poor conductors (carbon is the famous exception) |
| hammering | malleable — flatten into sheets | brittle — shatter |
| drawing out | ductile — pull into wire | cannot be drawn into wire |
| state at room temperature | solid (mercury is the exception) | many are gases |
Worked example — reading the properties off a roof. Corrugated iron roof sheets are metal: rolled flat into sheets (malleable), strong, and cheap. The same roof gets painted, because iron rusts. The electric cable running into the house is copper (excellent electrical conductor) wrapped in plastic (a non-metal, and a very good electrical insulator). The overhead lines strung between pylons are usually aluminium, not copper — it conducts almost as well and is far lighter, so the pylons can stand further apart.
Every one of these decisions is a property being matched to a job.
Which set of properties describes most metals?
What word describes a material that can be hammered or rolled into a flat sheet without breaking?
A learner tests 10 material samples by placing each one in a simple circuit with a torch bulb. The bulb lights for 6 of the samples. Assuming every conductor lit the bulb, how many samples did not conduct electricity?
A learner holds a magnet against an aluminium ladder and nothing sticks. He concludes that aluminium is not a metal. What is wrong with his reasoning?