Brass is an alloy of which two metals?

copper and zinc. Bronze is copper and tin; brass is copper and zinc.

Why are alloys harder than pure metals?

Different-sized atoms stop the layers sliding. The regular layers are broken up.

Why is stainless steel used for cutlery?

It does not rust. It is also hard, so it keeps its shape and edge.

a mixture of a metal with other elements. The elements are mixed, not chemically joined.

Which of these is an alloy?

steel. Steel is iron mixed with carbon and other elements.

Alloys · Cambridge IGCSE Co-ordinated Sciences (9

In plain words

Pure metals are often too soft to be much use: you can bend a pure gold ring with your fingers. Melt a metal with a little of something else and you get an alloy, which is harder and stronger. Almost every "metal" object around you is really an alloy.

Three things to know

An alloy is a mixture of a metal with other elements. Brass is copper and zinc. Stainless steel is iron with chromium, nickel and carbon.
In a pure metal the layers of atoms slide easily. In an alloy the different-sized atoms break up the layers, so they can't slide: the alloy is harder and stronger.
Stainless steel is used for cutlery because it is hard and does not rust.

Tips and tricks

An alloy is a mixture, not a compound: the elements are not chemically joined.
"Different-sized atoms distort the layers, so they can't slide over each other" is the full explanation of hardness.

5 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Alloys: 5 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

Brass is an alloy of which two metals?
- iron and carbon
- copper and zinc (the answer)
- copper and tin
- aluminium and copper
Bronze is copper and tin; brass is copper and zinc.
Why are alloys harder than pure metals?
- They have stronger atoms.
- Different-sized atoms stop the layers sliding. (the answer)
- They are compounds.
- They are heavier.
The regular layers are broken up.
Why is stainless steel used for cutlery?
- It is soft.
- It does not rust. (the answer)
- It is cheap.
- It is a good insulator.
It is also hard, so it keeps its shape and edge.
What is an alloy?
- a compound of two metals
- a mixture of a metal with other elements (the answer)
- a pure metal
- a metal oxide
The elements are mixed, not chemically joined.
Which of these is an alloy?
- iron
- copper
- steel (the answer)
- aluminium
Steel is iron mixed with carbon and other elements.

5 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

3 questions, 6 marks. Write your answers on paper, then check them.

Alloys

Cambridge IGCSE Co-ordinated Sciences (9–1) 0973 · 6 marks · papermunch.org

Name ______________________________ Date ______________

State what is meant by an alloy.[1]
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A mixture of a metal with one or more other elements.
I got this one
Explain why an alloy is harder than the pure metal.[3]
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The atoms of the added element are a different size, so they distort the regular layers of metal atoms. The layers can no longer slide over each other easily.
I got this one
Name an alloy used to make cutlery and give two reasons why it is suitable.[2]
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Stainless steel: it is hard, and it resists rusting.
I got this one

Answers: Alloys

1. A mixture of a metal with one or more other elements.
2. The atoms of the added element are a different size, so they distort the regular layers of metal atoms. The layers can no longer slide over each other easily.
3. Stainless steel: it is hard, and it resists rusting.