The World of Metals and Non-metals

About this chapter

The World of Metals and Non-metals is Chapter 4 of Class 7 Curiosity. Through Yashwant and Anandi's visit to a Rajasthan ironsmith, Sudarshan uncle, the chapter introduces metals as the substances behind everyday tools — tawa, balti, chimta, phawra, kulhadi, khurpi, jeli. Five physical properties of metals are built hands-on: malleability (beaten into thin sheets like silver vark and aluminium foil; gold and silver are most malleable), ductility (drawn into wires; one gram of gold can be drawn into a 2 km wire; metal wires in veena, sitar, violin, guitar), sonority (the ringing sound of a metal spoon, a school bell, ghungroos), conduction of heat (metals are good conductors, wood a poor conductor — why cooking vessels are metal with wooden handles), and conduction of electricity (metals make a tester bulb glow; rubber and plastic do not — why screwdriver handles and electrician's gloves are insulators). The chapter then turns to rusting (iron + moist air = brown rust; bottles A, B, C activity), corrosion (green on copper, black on silver), and the wonder of ancient Indian metallurgy at the rust-resistant Iron Pillar of Delhi (Chandragupta II, 1600+ years old). Non-metals — sulfur, phosphorus, oxygen, hydrogen, nitrogen, carbon, chlorine, iodine — are introduced through the contrast: dull, brittle, non-sonorous, poor conductors, with acidic oxides (sulfur dioxide → sulfurous acid; magnesium oxide gives a basic solution turning red litmus blue). The chapter closes with everyday uses of non-metals — oxygen for respiration, nitrogen for fertilisers, chlorine for water purification, iodine as antiseptic. CTET Paper 2 Science tests this chapter through property-substance match-ups, activity-condition reasoning (which bottle rusts), basic/acidic oxide statements, and pedagogy of malleability/ductility demonstrations. The four tests cover these ideas at exam depth.