Revision Notes for Class 7 Science Chapter 4: The World of Metals and Non-metals

Quick revision notes summarizing all key concepts from Class 7 Science Chapter 4 “The World of Metals and Non-metals”. These Class 7 Science Chapter 4 notes are ideal for quick revision just before exams.

• Metals are generally lustrous, malleable (can be beaten into sheets), ductile (can be drawn into wires), sonorous (produce a ringing sound), and good conductors of heat and electricity. Examples: copper, aluminium, iron, gold, zinc, sodium.
• Non-metals are generally non-lustrous, brittle, poor conductors of heat and electricity, and often exist as gases at room temperature. Examples: sulphur, oxygen, nitrogen, carbon, phosphorus. Exception: graphite (a form of carbon) is a non-metal but conducts electricity well.
• Metal oxides are generally basic in nature (turn red litmus paper blue), e.g., magnesium oxide.
• Non-metal oxides are generally acidic in nature (turn blue litmus paper red), e.g., sulphur dioxide forms sulphurous acid in water.
• Rusting of iron requires both air (oxygen) and water/moisture to occur; removing either factor prevents rusting.
• Sodium is a highly reactive metal that reacts vigorously with water/air and is stored in kerosene oil for safety.
• Copper is preferred over iron for boiling-water vessels because it conducts heat well and resists rusting/corrosion better.
• Only a few metals (like gold and silver) are used for jewellery because they are lustrous, soft enough to shape, and resist corrosion.
• Protective coatings (like zinc galvanisation) prevent iron from rusting by blocking air and moisture contact.
• Everyday uses of metals: cooking vessels (heat conduction), electrical wiring (electrical conduction, ductility), foil/wrapping (malleability). Everyday uses of non-metals: insulation (poor conductors), matchsticks (brittle, reactive), breathing (oxygen), pencils/batteries (graphite).

NCERT Solutions: Class 7 Science Chapter 4
Extra Questions: Class 7 Science Chapter 4

For the full chapter, see the Class 7 Science book page and the Class 7 Science Formulas Handbook.

Written by Satish

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