Properties, Uses & Alloys of Metals (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award): Chemistry): Flashcards
Exam code: 0654 & 0973
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- FrontProperties of Metals
What are four general physical properties of metals?
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What are four general physical properties of metals?
General physical properties of metals include:
High electrical and thermal conductivity
Malleable
Ductile
High melting and boiling points.
Metals conduct electricity because they have ______ electrons that are free to move through the metal structure.
Metals conduct electricity because they have delocalised electrons that are free to move through the metal structure.
True or False?
Non-metals are generally malleable and ductile.
False.
Non-metals are generally brittle when solid. They are not malleable or ductile (graphite is an exception).
When a metal reacts with cold water, it forms a metal ______ and ______ gas.
When a metal reacts with cold water, it forms a metal hydroxide and hydrogen gas.
What are the products when a metal reacts with steam?
When a metal reacts with steam, the products are a metal oxide and hydrogen gas.
What is the correct test for hydrogen gas, and what result confirms its presence?
The correct test for hydrogen gas is to hold a lighted splint near the gas.
A squeaky pop confirms hydrogen is present.
What are the products when iron reacts with dilute hydrochloric acid?
Write a word equation.
Iron reacts with dilute hydrochloric acid to produce iron(II) chloride and hydrogen gas.
Iron + hydrochloric acid → iron(II) chloride + hydrogen
Why do metals have high melting and boiling points compared to most non-metals?
Metals have high melting and boiling points because of the strong electrostatic attraction between positive metal ions and delocalised electrons (metallic bonding). A large amount of energy is needed to break these bonds.
Why is aluminium used to make aircraft bodies?
Aluminium is used in aircraft bodies because it has a low density (is lightweight) combined with high strength, giving it a high strength-to-weight ratio.
Aluminium is used for overhead power cables because it has good ______ conductivity and a ______ density.
Aluminium is used for overhead power cables because it has good electrical conductivity and a low density.
True or False?
Aluminium is resistant to corrosion because it is an unreactive metal.
False.
Aluminium is actually a reactive metal. It is resistant to corrosion because it reacts with oxygen to form a thin, protective layer of aluminium oxide on its surface, which prevents further reaction.
Why is copper used for electrical wiring?
Copper is used for electrical wiring because it is an excellent conductor of electricity and is ductile, meaning it can be drawn into thin wires.
Copper is used for water pipes because it is ______, non-toxic and does not react with ______.
Copper is used for water pipes because it is malleable, non-toxic and does not react with water.
State two properties of aluminium that make it suitable for use in food cans.
Aluminium is suitable for food cans because it is resistant to corrosion (including from acidic foods) and is non-toxic.
What is an alloy?
An alloy is a mixture of a metal with one or more other elements. Most alloys contain more than one metal, but some contain non-metals (for example, steel contains carbon).
Brass is an alloy of ______ and ______. It is harder and stronger than either pure metal.
Brass is an alloy of copper and zinc. It is harder and stronger than either pure metal.
True or False?
Stainless steel is a compound of iron and chromium.
False.
Stainless steel is an alloy (a mixture), not a compound. It is a mixture of iron with other elements such as chromium, nickel and carbon. Since it is a mixture, the components are not chemically combined.
Why is stainless steel used to make cutlery?
Stainless steel is used for cutlery because of its hardness and resistance to rusting (corrosion).
Explain, in terms of structure, why alloys are generally harder than the pure metals they contain.
Alloys contain atoms of different sizes, which distorts the regular arrangement of atoms. This distortion makes it more difficult for the layers to slide over each other, so alloys are harder and stronger than pure metals.
In an alloy, atoms of ______ sizes distort the layers, preventing them from ______ over each other.
In an alloy, atoms of different sizes distort the layers, preventing them from sliding over each other.
How would you identify a diagram representing an alloy rather than a pure metal?
A diagram of an alloy shows particles (atoms) of unequal sizes arranged in distorted or irregular layers. A pure metal shows particles of equal size in a regular, ordered arrangement.
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