Materials Chapter Notes | Science Olympiad for Class 3 PDF Download

What is Materials?

Material is anything that things can be made from. For example, wood is a material used to make tables and chairs, and cloth is a material used to make clothes.

Need for Classification

Every object has different properties and is made from various materials. It's hard to study them all one by one, so we group them to make it easier.

• Classification: Sorting objects into groups based on their texture, properties, or the material they are made of.
• Benefits of Classification:
  • Helps study similar objects together.
  • Helps find alternative materials when needed.
  • Allows us to understand the common properties of different materials.
  • Helps us choose the right material for a specific use.
• Example: A chair can be made from metal, wood, or fabric, but they each have different properties. Classification helps us understand these differences.

Classification of Materials

Can man-made materials be better than natural materials?

Yes, some man-made materials can be better than natural ones, but they can also harm nature because they do not break down easily. They also use a lot of energy and resources to be made.

Materials can be grouped into natural or man-made based on where they come from.

• Natural Materials: These come from nature. Examples: Wood, fibre.
• Man-made Materials: These are made by humans using raw materials. Examples: Paper, plastic.
• Materials from Plants: We get things like fruits, cereals, wood, fibres, and resins from plants.
• Materials from Animals: Animals give us things like meat, honey, wool, leather, and feathers.
• Materials from Earth: The Earth gives us rocks, minerals, and salts. Examples: Iron for rods, copper for wires, and gold for jewellery.
• Biotic Materials: Materials from living things like plants and animals.
• Abiotic Materials: Materials from non-living things like rocks and minerals.
• Man-made Materials: Humans create these materials from natural resources. Examples: Plastic, rubber, glass, paper.
• From Natural to Man-made: Some natural materials need small changes to be useful, while others need to be processed in factories.

Properties of Materials

1. Physical Appearance

Materials can be sorted by how they look and feel.

• Colour: Different materials have different colours.
• Hard or Soft: Some materials are hard like rocks, and some are soft like cotton.
• Hot or Cold: Some materials feel hot, while others feel cold.
• Elasticity: Some materials can stretch and bounce back, like rubber.
• Soft or Rough: Some materials are soft to touch, like silk, while others are rough, like sandpaper.
• Weight: Some materials are heavy like metal, while others are light like paper.

2. State of Material

• Materials can be solid, liquid, or gas.
• Example: A plastic water bottle is solid, hair oil is a liquid, and deodorant is a gas.

3. Temperature Tolerance

• Different materials behave differently at different temperatures. They have different boiling, melting, and freezing points.

4. Brittleness

• Some materials break easily, while others do not.
• Example: Chalk breaks easily, but iron does not. Diamond is the hardest material and cannot be broken even with a hammer.

5. Conductivity

• Some materials allow heat and electricity to pass through them, called conductors. Examples: Iron, copper, silver, and seawater.
• Materials that do not allow heat and electricity to pass through them are called insulators. Examples: Wood, plastic, and rubber.

6. Water Absorption

• Some materials soak water easily, like cotton, wool, and sponge.
• Others, like plastic, wood, and nylon, do not absorb water.

7. Magnetism

• Magnetism is the ability of a material to get attracted to a magnet.
• Examples: Iron, nickel, and cobalt are attracted to magnets, but plastic, wood, and rubber are not.

8. Ability to Pass Light

• Transparent Objects: These allow light to pass through them. Examples: Glass, water, and air.
• Opaque Objects: These do not allow light to pass through. Examples: Wood, rubber, and brick.
• Translucent Objects: These let some light pass through. Examples: Ground glass and butter paper.

9. Flammability

• Flammable materials catch fire easily at room temperature. Examples: Paper, dry twigs, and cotton.
• Some materials do not catch fire easily and are called inflammable. Examples: Steel, iron, and glass.

10. Toxicity

• Some materials contain chemicals that can be dangerous if touched or consumed.
• Examples: Acids, pesticides, and lead.

11. Corrosion

• Corrosion happens when materials, like metals, get damaged due to air, moisture, or chemical reactions.
• Examples: Iron and copper corrode easily, while plastic, glass, and aluminium do not.

Changes in the properties

The properties of materials can change when they are exposed to different factors.
Example: When paper burns, it turns into ashes. The properties of paper and ash are very different.
Let’s look at examples where properties change and where they do not:

• No Change: Weighing water, cutting a fruit, breaking glass, making wooden furniture, hammering a metal object.
• Change in Property: Digestion of food, ripening and rotting of fruit, caramelizing sugar, burning wooden blocks, rusting of a metal sheet.