Starter quiz
- Transition metals like copper and zinc are used in electrical applications because they are excellent ______ of electricity.
- 'conductors' ✓
- When a metal reacts with oxygen, it often forms a ______.
- 'metal oxide' ✓
- A ______ is formed when two or more elements are chemically bonded together.
- 'compound' ✓
- Arrange the following metals in order of reactivity with oxygen (most reactive at the top, least reactive at the bottom).
- 1⇔potassium
- 2⇔zinc
- 3⇔iron
- 4⇔silver
- 5⇔gold
- The ability of a metal to be hammered into thin sheets without breaking is called...
- malleability ✓
- conductivity
- ductility
- flexibility
-
- The resistance of a metal to being scratched or dented is called ______.
- 'hardness' ✓
Exit quiz
- What is sacrificial protection?
- Painting a metal to prevent corrosion.
- Using a more reactive metal to corrode preferentially and protect another metal. ✓
- Covering a metal with plastic to prevent air exposure.
- Cleaning a metal regularly to prevent tarnishing.
-
- Which metal is often used to galvanise iron?
- copper
- zinc ✓
- silver
- gold
-
- Which process involves the use of electricity to prevent corrosion and improve appearance?
- galvanising
- electroplating ✓
- anodising
- alloying
-
- What is the purpose of using a more reactive metal in sacrificial protection?
- To increase the metal's strength.
- To corrode preferentially and protect the less reactive metal. ✓
- To enhance the metal's colour.
- To make the metal more flexible.
-
- Rusting is a specific type of corrosion affecting ______ in the presence of water and oxygen.
- 'iron' ✓
- Complete the word equation for the rusting of iron. iron + ______ → (hydrated) iron(Ⅲ) oxide
- 'oxygen + water' ✓
Worksheet
Presentation
Video
Lesson Details
Key learning points
- Corrosion is a general process of degradation of metals through various causes.
- Rusting is a specific type of corrosion, affecting iron in the presence of air and moisture.
- A metal oxide layer can protect the underlying metal if the oxide forms a physical barrier.
- Some coatings are reactive and contain a more reactive metal to provide sacrificial protection, e.g. zinc to galvanise.
- Electroplating can be used to improve the appearance and/or the resistance to corrosion of metal objects.
Common misconception
Students often believe rusting refers to the oxidation of any metal, and that corrosion is linked to the hazard 'corrosive'.
Highlight the conditions required for rusting, and the general description of corrosion.
Keywords
Rusting - The corrosion of iron or steel, in the presence of water and oxygen.
Corrosion - The gradual deterioration of a substance when it reacts with substances in the environment, for example when a metal oxidises in air.
Sacrificial protection - Using a more reactive metal to corrode preferentially, to protect another metal from corrosion.
Tarnishing - The process by which a thin, discoloured layer forms on the surface of a metal due to reactions with the environment, e.g. oxidation.
Electroplating - A process that uses electricity to deposit a thin layer of metal onto the surface of another conductive object.