New
New
Year 10
AQA
Higher

Metal alloys

I can evaluate the metallic structure model in terms of its ability to explain some physical properties of metals and metal alloys.

New
New
Year 10
AQA
Higher

Metal alloys

I can evaluate the metallic structure model in terms of its ability to explain some physical properties of metals and metal alloys.

Lesson details

Key learning points

  1. In pure metals, ions are arranged in a regular structure with delocalised electrons between them
  2. If a metal is stretched or forced out of shape, its ions are able to move position without the metallic bonds breaking
  3. An alloy is a mixture of different metal elements or of metals with non metal elements (i.e. carbon)
  4. Ions of different metal elements may be different sizes and have different electrical charges
  5. The structure of an alloy is not as regular as a pure metal and this affects its properties

Common misconception

The metallic structure model is a replication of reality. Therefore, metals contain seawater. The concept of electric current is challenging. Some may think that electrons jump from atom to atom.

Discuss why scientists use models with the pupils, explaining that a model is only as good as what it can explain, so it develops over time. Remind pupils how an electric circuit works before discussing why metals are good conductors.

Keywords

  • Alloy - An alloy is a mixture of two or more elements, where at least one element is a metal.

  • Physical properties - A physical property is a characteristic of a substance that can be observed or measured. For example, the temperature at which a substance melts.

  • Delocalised electron - Electrons are said to be delocalised when they are free to move through the structure of a metal and can carry an electrical current.

  • Molten - Molten is the term used to describe a liquid substance formed by heating solid metals, glass, or rocks.

Use a 3D physical model to help pupils visualise the giant metallic structure. A layer of plastic balls in a tray works well. To illustrate how this giant lattice is disrupted in an alloy, add a larger ball into one of the rows.
Teacher tip

Equipment

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Loading...

6 Questions

Q1.
Which of the following diagrams models the arrangement of particles in a metal?
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
Q2.
Which of the following are common physical properties of metals?
low melting point
Correct answer: ductile
Correct answer: malleable
brittle
Q3.
Match the following physical properties of metals with the corresponding reasons for each property.
Correct Answer:ductile and malleable,Ions are arranged in layers that can easily slide over each other.

Ions are arranged in layers that can easily slide over each other.

Correct Answer:good thermal and electrical conductors,Ions are surrounded by a 'sea' of delocalised electrons.

Ions are surrounded by a 'sea' of delocalised electrons.

Correct Answer:high melting points,Strong electrostatic attraction between ions (+) and electrons (–).

Strong electrostatic attraction between ions (+) and electrons (–).

Q4.
Metallic structures consist of surrounded by __________.
Correct answer: positive metal ions
Correct answer: a 'sea' of delocalised electrons
negative metal ions
metal atoms
Q5.
Which force of attraction binds together the particles in a giant metallic structure?
Correct Answer: electrostatic
Q6.
Metals are malleable because...
Correct answer: they can be hammered into shape without breaking.
they can be pulled into wire.
Correct answer: the layers of metal ions can easily slide over each other.
they contain delocalised electrons.

6 Questions

Q1.
Match the following key terms to their definitions.
Correct Answer:alloy,A mixture of two or more elements, at least one of which is a metal.

A mixture of two or more elements, at least one of which is a metal.

Correct Answer:delocalised electron,Negatively charged particle free to move through the metal structure.

Negatively charged particle free to move through the metal structure.

Correct Answer:molten,A liquid substance formed by heating solid metal, glass or rocks.

A liquid substance formed by heating solid metal, glass or rocks.

Correct Answer:physical poperty,A characteristic of a substance that can be observed or measured.

A characteristic of a substance that can be observed or measured.

Q2.
A metallic bond is a strong electrostatic force of attraction between the positively charged and the delocalised electrons in a metal.
Correct Answer: metal ions, ions, cations, metal cations
Q3.
True or false? Alloys have a disrupted or irregular lattice structure.
Correct answer: true
false
Q4.
Which of the following statements about pure metals and alloys are correct?
Most alloys are more ductile than pure metals.
Correct answer: Most alloys are less malleable than pure metals.
Correct answer: Alloys and pure metals are both good electrical conductors.
Most alloys are poor thermal conductors.
Q5.
Aluminium atoms form Al³⁺ ions and lithium atoms form Li⁺ ions. Which of the following statements about aluminium and lithium ions are correct?
Lithium atoms gain one electron to form lithium ions.
Aluminium ions and lithium ions are the same size.
Correct answer: Aluminium contains more delocalised electrons per ion than lithium.
Correct answer: Aluminium atoms lose three electrons to form aluminium ions.
Q6.
The melting point of a substance is an example of a property.
Correct Answer: physical