🌍 Chapter Summary with NCERT Solution: The World of Metals and Non-Metals
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| The World of Metals and Non-Metals (AI Generated Image) |
This chapter helps students understand metals, non-metals, and their properties through real-life examples and simple experiments.
🔨 Introduction
Yashwant and Anandi visit an ironsmith to learn how metals like iron are used to make tools such as tawas, spades, and buckets. The chapter begins with this story to show how metals play a vital role in our daily lives.
⚙️ Properties of Materials
1. Malleability
- Metals can be beaten into thin sheets without breaking.
- Examples: Aluminium foil, silver foil on sweets.
- Metals like copper, iron, and aluminium show malleability.
- Non-metals like coal and sulphur are brittle and break easily.
2. Ductility
- Metals can be drawn into wires.
- Example: Copper and aluminium wires used in electricity.
- Gold is the most ductile metal — 1 gram can stretch into a 2 km long wire!
3. Sonority
- Metals produce a ringing sound when struck (like a school bell or ghungroo).
- Non-metals like coal or wood produce dull sounds.
4. Conductivity of Heat
- Metals are good conductors of heat, so they are used for cooking utensils.
- Handles are made of wood or plastic because they are poor conductors.
5. Conductivity of Electricity
- Metals allow electric current to pass through them.
- Non-metals like rubber and wood do not.
- That’s why electricians use rubber gloves for safety.
🌧️ Effect of Air and Water on Metals
Rusting of Iron
- When iron reacts with air and water, it forms brown rust.
- This process is called rusting and causes damage to iron tools and structures.
- Rusting can be prevented by painting, oiling, greasing, or galvanisation (coating with zinc).
- Example: The Iron Pillar of Delhi has resisted rust for over 1600 years.
Corrosion
- Other metals also react with air and water:
- Copper forms a green coating.
- Silver turns black.
- Corrosion weakens metals and causes loss of money and resources.
🔥 Reaction of Metals with Air and Water
- Magnesium burns in air producing magnesium oxide, which is basic in nature.
- Sodium reacts vigorously with air and water, so it is stored in kerosene.
🌡️ Non-Metals and Their Behaviour
- Sulphur burns in air to form sulphur dioxide, which dissolves in water to make sulphurous acid — hence acidic in nature.
- Non-metals do not conduct heat or electricity, are not malleable or ductile, and are soft and dull in appearance.
- Examples: Sulphur, Phosphorus, Oxygen, Carbon, Nitrogen.
- Phosphorus is stored in water as it catches fire in air.
💧 Importance of Non-Metals in Daily Life
- Oxygen – needed for breathing.
- Carbon – found in proteins, fats, and carbohydrates.
- Nitrogen – used in fertilizers for plant growth.
- Chlorine – used in water purification.
- Iodine – used as an antiseptic on wounds.
🧠 Key Differences Between Metals and Non-Metals
| Property | Metals | Non-Metals |
| - | -- | - |
| Lustre | Shiny | Dull |
| Malleability | Can be beaten into sheets | Brittle |
| Ductility | Can be drawn into wires | Not ductile |
| Conductivity | Good conductor of heat and electricity | Poor conductor |
| Nature of Oxides | Basic | Acidic |
| Reaction with Water | Some react | Generally do not react |
💡 In a Nutshell
- Metals are lustrous, malleable, ductile, and good conductors.
- Non-metals are non-lustrous, brittle, and poor conductors.
- Rusting and corrosion damage metals but can be prevented.
- Both metals and non-metals are essential in daily life — from cooking and electricity to breathing and farming.
~~The END~~
Chapter 4 The World of Metals and Non-Metal
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