Grade 7 Pre-technical MATERIALS FOR PRODUCTION – Metallic materials Notes

What are metallic materials?

Metallic materials (metals) are shiny, hard materials that can usually conduct electricity and heat. They can be shaped by hammering, heating or stretching. Metals are used to make many everyday things like pans, nails, wire, and roofs.

Common metals you meet in Kenya

Important properties (simple)

• Shiny — many metals look shiny when polished.
• Strong — metals can carry heavy weights (used in buildings).
• Malleable — you can bend or hammer them into shapes.
• Ductile — some can be pulled into thin wires (like copper).
• Conductive — they let electricity and heat pass through.
• Some rust — iron and steel can get reddish rust when wet.

Alloys — mixed metals

An alloy is a mix of two or more metals. Mixing makes new useful materials:

• Steel = iron + carbon (stronger than pure iron).
• Stainless steel = steel + chromium (does not rust easily; used for cutlery and kitchen sinks).
• Brass = copper + zinc (used for locks and decorations).
• Bronze = copper + tin (used for coins, statues).

How to test metals at home (safe & simple)

1. Magnet test: Use a small magnet. Iron and many steels stick to the magnet. Aluminium and copper do not.
2. Look and feel: Check colour and shine. Copper looks reddish-brown; aluminium is light grey and light weight.
3. Scratch test: Try to scratch the metal gently with a coin. Softer metals scratch more easily. Do this with care and under supervision.

Uses of metals in Kenya (everyday examples)

• Corrugated iron sheets for roofs (houses and shops).
• Cooking pots and stainless steel plates used in homes and hotels.
• Nails, hinges and locks for doors and furniture.
• Electric wires made of copper in houses and street lights.
• Matatu and car body repairs use steel and aluminium parts.
• Recycling centres buy old metal to remelt and make new items.

Care and safety

• Keep metals dry when possible to stop rust (iron + water = rust).
• Wear gloves when handling sharp metal pieces to avoid cuts.
• Do not put sharp metal in fires or play near cutting tools — ask an adult for help.
• Recycle metal scraps — it helps the environment and can earn money.

Quick summary

Metals are strong, shiny materials used for buildings, tools, wires and cooking. Some rust, some are light, and mixing metals makes useful alloys like steel and brass. You can test metals with a magnet and by looking at them. Always be safe and recycle when you can.

Mini quiz (answer with a friend or teacher)

1. Which metal is light and used for drink cans?
2. What test can tell you if a metal is iron or not?
3. Name one alloy and one use for that alloy.