AlloysOxford AQA IGCSE Chemistry: Flashcards
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Question
Define an alloy.
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- Define an alloy.
- A mixture of at least two elements, at least one of which is a metal.
- Are alloys compounds or mixtures?
- Mixtures - the elements are not chemically combined in a fixed ratio.
- What are steels made from?
- Iron mixed with carbon, and sometimes other metals.
- Why are alloys often more useful than pure metals?
- Alloys often have properties different from the metals they contain, typically being harder or stronger.
- Why does alloying tend to make a metal harder?
- Atoms of a different size distort the regular layers of metal atoms, making it harder for the layers to slide over each other.
- How do the layers of atoms in a pure metal compare to those in an alloy?
- A pure metal has regular, uniform layers that slide easily; an alloy has distorted layers due to differently sized atoms, which resist sliding.
- Give an example of a family of alloys and what they are made from.
- Steels, made from iron mixed with carbon (and sometimes other metals).
- Can the composition of steel vary?
- Yes, and different compositions give different properties suited to different uses.
- What is a common mistake to avoid when describing an alloy?
- Describing it as a compound - an alloy is a mixture, not a compound.