Main Menu
  • School
    • Close
    • CBSE English Medium
    • CBSE Hindi Medium
    • UP Board
    • Bihar Board
    • Maharashtra Board
    • MP Board
    • Close
  • English
    • Close
    • English Grammar for School
    • Basic English Grammar
    • Basic English Speaking
    • English Vocabulary
    • English Idioms & Phrases
    • Personality Enhancement
    • Interview Skills
    • Close
  • Sarkari Exam Prep
    • Close
    • All Govt Exams Preparation
    • MCQs for Competitive Exams
    • Notes For Competitive Exams
    • NCERT Syllabus for Competitive Exam
    • Close
  • Study Abroad
    • Close
    • Study in Australia
    • Study in Canada
    • Study in UK
    • Study in Germany
    • Study in USA
    • Close
Science Class 7 || Menu
  • Videos Science Class 7
  • MCQ Science Class 7
  • Notes Science Class 7
  • Question Answer Science Class 7
  • Important Questions Science Class 7
  • Sample Paper Science Class 7
  • Previous Year Paper Science Class 7
  • Book Science Class 7
  • Nutrition in Plants
  • Nutrition in Animals
  • Heat
  • Acids, Bases and Salts
  • Physical and Chemical Changes
  • Respiration in Organisms
  • Transportation in Animals and Plants
  • Reproduction in Plants
  • Motion and Time
  • Light
  • Science Class 7

Notes Chapter 4 Class 7 Science Curiosity NCERT

Advertisement

The World of Metals and Non-metals


1. Properties of Materials

Malleability

  • Definition: Ability to be beaten into thin sheets.
  • Metals: Copper, aluminium, iron are malleable (e.g., aluminium foil, silver foil).
  • Non-metals: Coal, sulfur are brittle; wood is neither malleable nor brittle.
  • Exceptions: Sodium, potassium (soft metals); mercury (liquid metal).

Ductility

  • Definition: Ability to be drawn into wires.
  • Metals: Copper, aluminium, gold (e.g., electrical wires, jewellery).
  • Non-metals: Coal, sulfur are not ductile.
  • Fact: 1 gram of gold can make a 2 km wire.

Sonority

  • Definition: Ability to produce a ringing sound when struck.
  • Metals: Sonorous (e.g., bells, ghungroos).
  • Non-metals: Non-sonorous (dull sound).

Conduction of Heat

  • Metals: Good conductors (e.g., cooking vessels).
  • Non-metals: Poor conductors (e.g., wooden handles).

Conduction of Electricity

  • Metals: Good conductors (e.g., copper wires).
  • Non-metals: Poor conductors (e.g., rubber gloves, plastic handles).

2 .Effect of Air and Water on Metals: Iron

  • Rusting: Brown deposit (rust) forms on iron when exposed to both air and water.
  • Corrosion: Gradual deterioration of metals (e.g., green coating on copper, black on silver).
  • Prevention: Painting, oiling, greasing, galvanisation (zinc coating).
  • Fact: Iron Pillar of Delhi (1600+ years) resists rust due to ancient metallurgy.

3 Effect of Air and Water on Other Metals

  • Magnesium: Burns with white flame, forms magnesium oxide (basic).
  • Sodium: Stored in kerosene; reacts vigorously with air and water.

4.Non-metals

  • Properties: Soft, non-lustrous, brittle, non-ductile, non-sonorous, poor conductors.
  • Examples: Sulfur, phosphorus, oxygen, carbon, nitrogen.
  • Sulfur: Burns to form sulfur dioxide (acidic); no reaction with water.
  • Phosphorus: Stored in water to prevent burning in air.

 5. Importance of Non-metals

  • Oxygen: Essential for respiration.
  • Carbon: Building block of life (proteins, fats, carbohydrates).
  • Nitrogen: Used in fertilisers for plant growth.
  • Chlorine: Water purification.
  • Iodine: Antiseptic for wounds.

Key Points

  • Metals: Lustrous, hard, malleable, ductile, sonorous, good conductors; form basic oxides.
  • Non-metals: Non-lustrous, soft, brittle, non-ductile, non-sonorous, poor conductors; form acidic oxides.
  • Elements: 118 known; metals and non-metals are sub-categories.
  • Applications: Metals in utensils, tools, technology; non-metals in life processes, industries.

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Advertisement

CBSE Delhi Question Answer of Chapters in PDF

Free Sample Papers and Previous Years' Question Papers for CBSE Exams from the Official CBSE Academic Website (CBSE.nic.in) in Delhi, Rajasthan, Uttar Pradesh and Bihar

Download CBSE / NCERT Book, Notes & MCQ Online Test / Mock Test

Online Quiz with Answers for Objective Questions in Hindi and English

Advertisement

Maharashtra Board Marathi & English Medium

Just Launched! Access Maharashtra Board Exam MCQs, Previous Year Papers, Textbooks, Solutions, Notes, Important Questions, and Summaries—available in both Marathi and English mediums—all in one place Maharashtra Board

Android APP

सरकारी Exam Preparation

Sarkari Exam Preparation Youtube

CBSE – दिल्ली, उत्तर प्रदेश, मध्य प्रदेश, बिहार, राजस्थान & हरियाणा Board हिंदी माध्यम

कक्षा 6 to 8 हिंदी माध्यम
कक्षा 9 & 10 हिंदी माध्यम
कक्षा 11 हिंदी माध्यम

State Board

यूपी बोर्ड 6,7 & 8
बिहार बोर्ड हिंदी माध्यम

CBSE Board

Mathematics Class 6
Science Class 6
Social Science Class 6
हिन्दी Class 6
सामाजिक विज्ञान कक्षा 6
विज्ञान कक्षा 6

Mathematics Class 7
Science Class 7
SST Class 7
सामाजिक विज्ञान कक्षा 7
हिन्दी Class 7

Mathematics Class 8
Science Class 8
Social Science Class 8
हिन्दी Class 8

Mathematics Class 9
Science Class 9
English Class 9

Mathematics Class 10
SST Class 10
English Class 10

Mathematics Class XI
Chemistry Class XI
Accountancy Class 11

Accountancy Class 12
Mathematics Class 12

Learn English
English Through हिन्दी
Job Interview Skills
English Grammar
हिंदी व्याकरण - Vyakaran
Microsoft Word
Microsoft PowerPoint
Adobe PhotoShop
Adobe Illustrator
Learn German
Learn French
IIT JEE
Privacy Policies, Terms and Conditions, About Us, Contact Us
Copyright © 2025 eVidyarthi and its licensors. All Rights Reserved.