IDENTIFICATION OF METALS

Subject : BASIC TECHNOLOGY

 

Term : FIRST TERM

 

Week: Week 6

 

Class : JSS1

 

 

Previous lesson : 

The pupils have previous knowledge of  MATERIALS AND PROCESSING – IDENTIFICATION OF WOOD

 

Topic :

IDENTIFICATION OF METALS

Behavioural objectives :

At the end of the lesson,  pupils would have learnt

  • different types of metals
  • Definition and Properties of Metal
  • Classes of Metal
  • Processing of Metal
  • Uses of Metal

Instructional Materials :

  • Wall charts
  • Pictures
  • Related Online Video
  • Flash Cards

Methods of Teaching :

  • Class Discussion
  • Group Discussion
  • Asking Questions
  • Explanation
  • Role Modelling
  • Role Delegation

 

Reference Materials :

  • Scheme of Work
  • Online Information
  • Textbooks
  • Workbooks
  • 9 Year Basic Education Curriculum
  • Workbooks

TOPIC: IDENTIFICATION OF METALS

CONTENT

  • Definition and Properties of Metal
  • Classes of Metal
  • Processing of Metal
  • Uses of Metal

DEFINITION OF METAL

METAL is a type of solid mineral substance that is usually hard and shiny. It conducts heat and electricity can travel through it.

Metals have characteristics which are different from those of the non-metals such as wood, plastics ceramics, rubber etc

PROPERTIES OF METAL

Metals can be identified by the following physical properties:

  1. Conductivity: Some metals have the ability to conduct heat and electricity.
  2. Fusibility: Some metals have the ability to be melted and cast into shapes.
  3. Magnetic: Some metals have the ability to attract iron.
  4. Ductility: Some metals have the ability to be drawn or stretched out into wires without breaking.
  5. Brittleness: Some metals have the ability to break or crack , when hit on the ground
  6. Malleability: Some metals have the ability to be hammered or beaten into shape without cracking.
  7. Toughness: Some metals have the ability to withstand (resist) bending, breaking, cracking or stretching.
  8. Density: Some metals have weight and volume.
  9. Colour (lustre): Some metals have the ability of having a shining appearance when polished.

CLASSES OF METAL

The metals used in engineering can be classified into categories

  1. Ferrous metals and their alloys
  2. Non-ferrous metals and their alloys

FERROUS METALS AND THEIR ALLOYS

This group of metals contains iron. The metals are, therefore, magnetic. Examples include wrought iron, cast iron and various grades of steel.

NON-FERROUS METALS AND THEIR ALLOYS

This group of metals have no iron . These metals are therefore not magnetic. Examples are aluminum, copper, brass etc.

EVALUATION

    1. State five properties of metal.
    2. Differentiate between ferrous and non-ferrous metal.

PROCESSING METALS

Most metals do not occur in a pure state. They are usually combined with other metals and earthly impurities to form what is called mineral ore. The ore is then mined and processed to extract the metal of interest. The extraction process differs from metal to metal.

  1. Casting:

Casting is the process of melting and pouring molten metal into the mould to take the shape of the mould when it cools down or solidifies.

  1. Smelting:

Smelting is the process of extracting metals from iron-ore dug from the ground .

  1. Annealing:

Annealing is the process by which metals can be softened.

USES OF METAL

Alloy metal composition Properties
Brass 65%copper and 35%zinc Soft material
Gilding metal 80% copper and 20 % zinc Polishes well and no corrosion
Bell metal 78% copper and 22% zinc Louder in sound than other metals

 

Ferrous metals Uses
Cast iron Cast iron in the manufacturing of machine parts , pipes, radiators, stoves, engine blocks
Carbon steel Carbon steels are used in the manufacturing of the automobile bodies gears, hacksaws ,hammers ,drill, knives
Alloy steels Alloy steels are used in the manufacturing of cables, steels, rail, wires , springs , shoves, ball-bearing, chisels etc.
Wrought Iron The wrought iron is used in the manufacturing of nails ,horse shoes, pipe ,wires, roofing sheets
Non-ferrous metal Uses
Aluminium Aluminium is used for manufacturing aircraft, cooking pots for its lightness.
Copper Copper is used for making telephone wires, water heater, pipes ,electric cables.
Zinc Zinc is used for the coating of iron and steel as a protection against rusting .It is used for wire-fence ,water tank reservoir ,bucket.
Brass Brass is for making musical instrument screws clocks.
Silver Silver is for ornament work ,mirror .
Nickel Nickel is used for plating iron and materials to give a shining slivering appearance . It is also used for making cooking pots and sauce pan.
Lead Lead is used for making lead pipes , storage batteries , chemicals and cover electric cables.
Tin Tin is used for making engine bearing, ball-bearing medals, coins , statues and collapsible tubes.

EVALUATION

  1. Explain the following methods of processing of metal (i) annealing (ii) smelting (iii) casting.
  2. State the uses of the following metals (i) alloy metals (ii) ferrous metals (iii) non-ferrous metals.

READING ASSIGNMENT

Read on Identification of Ceramics, Plastics and Rubber from Introductory Technology (JSS1) by Evans. Pages 32-35

WEEKEND ASSIGNMENT

  1. _____ is a type of solid mineral substance that is usually hard and shiny and that heat and electricity can travel through (a) Plastic (b) Rubber (c) Metal (d) Ceramics
  2. Some metals have the ability to be hammered or beaten into shape without cracking .This quality is known as (a) malleability (b) ductility (c) toughness (d) fusibility
  3. The group of metals that contains iron is known as (a) ferrous metals (b) non-ferrous metals (c) alloys. (d) terrazzo
  4. The group of metals that has no iron is not magnetic. Examples are as follow except

(a) aluminium (b) copper (c) steel (d) brass

  1. ______ is the process by the which metals can be softened.(a) Casting (b) Smelting (c) Annealing (d) Riveting

THOERY

  1. Define and state the properties of metals.
  2. State the classes of metals with examples.
  3. Explain the following methods of processing of metals (i) annealing (ii) smelting (iii) casting.
  4. State the uses of the following metals (i) alloy metals (ii) ferrous metals (iii) non-ferrous metals

Presentation

 

The topic is presented step by step

 

Step 1:

The class teacher revises the previous topics

 

Step 2.

He introduces the new topic

 

Step 3:

The class teacher allows the pupils to give their own examples and he corrects them when the needs arise

 

 

Conclusion

The lesson is concluded when the class teacher wraps up the lesson by giving the pupils some notes.

The class teacher also goes round to make sure that the notes are well copied or well written by the pupils.

He or she does the necessary corrections when and where  the needs arise.

 

 

Assignment

Prepare for the next lesson by reading about Properties of materials  – Metals

 

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