🔬 Chapter 4 — The World of Metals and Non-metals
Class 7 Science | Curiosity | EduGrown Notes
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⚒️ The World of Metals and Non-metals — all around us!
🔩 Properties of Metals
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✨Lustre = Metals have a shiny appearance called metallic lustre
🔨Malleability = Metals can be beaten into thin sheets without breaking (e.g., aluminium foil, silver foil on sweets)
〰️Ductility = Metals can be drawn into thin wires (e.g., copper wires in electrical fittings)
🔊Sonorous = Metals produce a ringing sound when struck
⚡Good Conductors = Most metals conduct heat and electricity well
💪Generally hard and strong (exceptions: sodium, potassium are soft; mercury is liquid)
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⚒️ Ironsmith beating metal into shape — malleability!
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🔩 Metal properties explored through activities
🪨 Properties of Non-metals
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💥Brittle = Non-metals like coal and sulfur break into pieces when hammered — NOT malleable
🔇Non-metals are generally NOT sonorous
🚫Non-metals are generally poor conductors of heat and electricity (insulators)
✨Non-metals generally do NOT have metallic lustre
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🪨 Coal & sulfur — non-metals that are brittle
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⚒️ Metals vs non-metals — comparing properties
📊 Metals vs Non-metals — Comparison
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| Property | Metals | Non-metals |
|---|---|---|
| ✨ Lustre | Shiny (metallic lustre) | Not shiny (dull) |
| 🔨 Malleability | Can be beaten into sheets | Brittle — breaks into pieces |
| 〰️ Ductility | Can be drawn into wires | Cannot be drawn into wires |
| ⚡ Conductivity | Good conductors of heat & electricity | Poor conductors (insulators) |
| 🔊 Sound | Sonorous (ringing sound) | Not sonorous |
| 💪 Hardness | Generally hard (except Na, K) | Generally soft (diamond is exception) |
| 🌡️ State | Mostly solid (Mercury is liquid) | Solid, liquid, or gas |
🌟 Examples & Uses
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🔩 Important Metals
FeIron — farming tools, buildings, bridges
CuCopper — electrical wires, utensils
AlAluminium — aeroplanes, foil, utensils
AuGold — jewellery, electronics
🪨 Important Non-metals
CCarbon — coal (fuel), diamond, graphite (pencil)
OOxygen — breathing, combustion
SSulfur — medicines, gunpowder
NNitrogen — air (78%), fertilisers
💡 Amazing Metal Facts!
🥇 Gold is so ductile that 1 gram can be drawn into a 2 km long wire!
🌊 Mercury is the only metal that is liquid at room temperature!
🔪 Sodium and Potassium are so soft they can be cut with a knife!
✨ Silver and Gold are the most malleable metals!
💎 Diamond (a form of carbon — non-metal) is the hardest natural substance!
🌊 Mercury is the only metal that is liquid at room temperature!
🔪 Sodium and Potassium are so soft they can be cut with a knife!
✨ Silver and Gold are the most malleable metals!
💎 Diamond (a form of carbon — non-metal) is the hardest natural substance!
⭐ Quick Summary
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📝 Key Points
🔩Metals: lustrous, malleable (sheets), ductile (wires), sonorous, good conductors, generally hard
🪨Non-metals: brittle, NOT malleable/ductile, poor conductors, not sonorous (generally)
🌟Key metals: Iron (tools), Copper (wires), Aluminium (foil/aircraft), Gold (jewellery)
🌟Key non-metals: Carbon (coal/diamond), Oxygen (breathing), Nitrogen (air/fertilisers)