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:
- Conductivity: Some metals have the ability to conduct heat and electricity.
- Fusibility: Some metals have the ability to be melted and cast into shapes.
- Magnetic: Some metals have the ability to attract iron.
- Ductility: Some metals have the ability to be drawn or stretched out into wires without breaking.
- Brittleness: Some metals have the ability to break or crack , when hit on the ground
- Malleability: Some metals have the ability to be hammered or beaten into shape without cracking.
- Toughness: Some metals have the ability to withstand (resist) bending, breaking, cracking or stretching.
- Density: Some metals have weight and volume.
- 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
- Ferrous metals and their alloys
- 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
-
- State five properties of metal.
- 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.
- 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.
- Smelting:
Smelting is the process of extracting metals from iron-ore dug from the ground .
- 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
- Explain the following methods of processing of metal (i) annealing (ii) smelting (iii) casting.
- 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
- _____ 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
- 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
- The group of metals that contains iron is known as (a) ferrous metals (b) non-ferrous metals (c) alloys. (d) terrazzo
- The group of metals that has no iron is not magnetic. Examples are as follow except
(a) aluminium (b) copper (c) steel (d) brass
- ______ is the process by the which metals can be softened.(a) Casting (b) Smelting (c) Annealing (d) Riveting
THOERY
- Define and state the properties of metals.
- State the classes of metals with examples.
- Explain the following methods of processing of metals (i) annealing (ii) smelting (iii) casting.
- 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
