Materials (Classes VI–VIII) • Topic 3 of 5

Metals & Non-Metals

NCERT Class 8 distinguishes metals from non-metals by physical and chemical properties. PHYSICAL properties of most METALS: they are LUSTROUS (have a shine), MALLEABLE (can be beaten into thin sheets — gold/aluminium foil), DUCTILE (can be drawn into wires — copper wires), good CONDUCTORS of heat and electricity, generally hard, and SONOROUS (make a ringing sound when struck — a school bell). Most are solid at room temperature with high melting points. NON-METALS are generally non-lustrous (dull), brittle (break/crumble when hammered, not malleable), poor conductors (insulators) of heat and electricity, and may be solid, liquid or gas. KEY EXCEPTIONS that CTET tests: MERCURY is a metal but is LIQUID at room temperature; SODIUM and POTASSIUM are metals yet so soft they can be cut with a knife; GRAPHITE (a form of carbon, a non-metal) is the exception that DOES conduct electricity; IODINE is a non-metal that is lustrous; and DIAMOND (carbon) is the hardest natural substance. CHEMICAL angle: metals react with oxygen to form basic oxides (which turn red litmus blue), non-metals form acidic oxides; reactive metals displace less reactive ones. A note for Paper II: a magnet attracts only certain metals (iron, nickel, cobalt) — NOT all metals — so 'attracted by a magnet' is a property of a few metals, not a test for 'metal'. PEDAGOGY/MISCONCEPTION: children believe 'all metals are attracted by magnets' and 'all metals are solid'; a hands-on test with copper (not magnetic) and a thermometer (liquid mercury) corrects both. HOW TESTED: 'which property/which exception' items, or matching a use to a property (copper for wires → ductile + conductor).

✅ Solved examples

1. Copper is drawn out into long thin wires for electrical wiring. The property that makes this possible is:
Ductility — the ability to be drawn into wires. (Its use in wiring also depends on copper being a good conductor of electricity.)
2. Which metal is unusual because it is a LIQUID at room temperature?
Mercury — the one common metal that is liquid at ordinary temperature; it is used in thermometers.
3. A school bell rings clearly when struck. The property of metals responsible for this is:
Sonorousness — metals are sonorous, producing a ringing sound when struck.
4. A teacher claims 'magnets attract all metals'. Why is this statement wrong, and how can a child test it?
Only iron, nickel and cobalt are magnetic; copper, aluminium and gold are NOT attracted. A child can simply bring a magnet near a copper wire or an aluminium spoon and see no attraction — correcting the misconception by direct evidence.

✏️ Practice — try these, take hints as needed

1. Gold and aluminium can be hammered into very thin foils. This property of metals is called:
Beaten into sheets, not drawn into wires.
Foil-making.
Malleability (the metal is malleable)
2. Which non-metal is the exception that conducts electricity and is used in pencil leads?
A form of carbon.
Used as an electrode too.
Graphite
3. Most non-metals break or crumble when hammered instead of flattening. They are therefore described as:
Opposite of malleable.
Like chalk or sulphur.
Brittle
4. Name two metals so soft that they can be cut with a knife.
Both are very reactive alkali metals.
Stored under kerosene.
Sodium and potassium

📝 Topic test — 8 questions

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