Metals and Non-metals — Class 10 Science
"Iron built civilisations. Silicon powers smartphones. Carbon underlies all life. Elements shape destinies."
1. About the Chapter
This chapter explores:
- Physical & chemical properties of metals and non-metals
- Reactivity series of metals
- Ionic compounds formation
- Extraction of metals from ores (metallurgy)
- Corrosion and prevention
Why Important
- Indian metallurgy (steel, aluminium, gold) is major industry
- Foundation for chemistry, materials science
- Critical for engineering
2. Physical Properties
Metals
- Lustrous (shiny) when polished
- Malleable (can be hammered into sheets)
- Ductile (can be drawn into wires)
- Hard (most are; exceptions: Na, K)
- Good conductors of heat and electricity
- High density
- High melting/boiling points (mostly)
- Sonorous (ring when struck)
- Solid at room temperature (except mercury — liquid)
Non-metals
- Dull (not shiny; exception: iodine)
- Brittle (break, don't bend)
- Poor conductors (exception: graphite — carbon)
- Low density
- Low melting/boiling points (mostly)
- Not sonorous
- Solid, liquid, or gas at room temp
Exceptions to Remember
- Mercury (Hg) — only metal LIQUID at room temp
- Bromine (Br) — only non-metal LIQUID at room temp
- Gallium and Caesium — metals with very low melting points (~30°C)
- Carbon (graphite) — non-metal that conducts electricity
- Diamond — hardest natural substance, made of carbon (non-metal)
3. Chemical Properties
Metals — Chemical Reactions
1. With Oxygen → Metal Oxide (BASIC)
- 2Mg + O₂ → 2MgO
- 4Al + 3O₂ → 2Al₂O₃
Metal oxides are BASIC (turn red litmus blue when dissolved in water).
2. With Water → Metal Hydroxide + H₂
- 2Na + 2H₂O → 2NaOH + H₂↑ (violent reaction!)
- Mg + 2H₂O → Mg(OH)₂ + H₂ (slow)
- Some metals (Au, Ag, Pt) DON'T react with water
3. With Acids → Salt + H₂
- Mg + 2HCl → MgCl₂ + H₂↑
- Au, Ag don't react with acids
4. With Other Metal Salts → Displacement
- Zn + CuSO₄ → ZnSO₄ + Cu (Zn more reactive than Cu)
Non-metals — Chemical Reactions
1. With Oxygen → Non-metal Oxide (ACIDIC)
- C + O₂ → CO₂ (acidic when dissolved)
- S + O₂ → SO₂
Non-metal oxides are ACIDIC.
2. With Hydrogen → Hydride
- 2H₂ + O₂ → 2H₂O (water = hydride of oxygen)
- N₂ + 3H₂ → 2NH₃
4. Reactivity Series
What is it?
A list of metals arranged in DECREASING order of reactivity.
Series (most → least reactive)
K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au
(Mnemonic: 'Please Stop Calling My Aunt Zelda In Public Hating Copper Mercury Silver Gold' — many versions exist.)
Importance
- A metal HIGHER in series DISPLACES a metal LOWER from its salt
- Example: Zn + CuSO₄ → ZnSO₄ + Cu (Zn > Cu in series)
- Reverse doesn't happen: Cu + ZnSO₄ → NO REACTION
Position of Hydrogen
Hydrogen is in the middle. Metals ABOVE H displace H from acids (give H₂). Metals BELOW H don't.
5. Ionic Compounds
Formation
- Metal loses electron(s) → forms positive ion (cation)
- Non-metal gains electron(s) → forms negative ion (anion)
- Cation and anion attract → IONIC BOND
Example: NaCl
- Na → Na⁺ + e⁻ (loses 1 electron)
- Cl + e⁻ → Cl⁻ (gains 1 electron)
- Na⁺ and Cl⁻ attract: NaCl
Properties of Ionic Compounds
- Crystalline solids
- High melting/boiling points
- Soluble in water (mostly)
- Conduct electricity when MOLTEN or DISSOLVED (not in solid state)
- Brittle — break along crystal planes
6. Extraction of Metals (Metallurgy)
Steps in Metallurgy
- Mining — get ore from earth
- Concentration — separate useful mineral
- Reduction — extract metal from ore
- Refining — purify the metal
Reduction Methods Depend on Reactivity
Most Reactive (K, Na, Ca, Mg, Al):
- Use ELECTROLYSIS (electric current)
- E.g., aluminium from bauxite: 2Al₂O₃ → 4Al + 3O₂
Moderately Reactive (Zn, Fe, Pb, Cu):
- Roast or calcine ore to oxide
- Then REDUCE with carbon: 2ZnO + C → 2Zn + CO₂
Least Reactive (Hg, Ag, Au):
- Often found in NATIVE form (pure)
- Heating alone may suffice: 2HgS + 3O₂ → 2HgO + 2SO₂; 2HgO → 2Hg + O₂
Indian Metallurgy
- India was first to extract zinc (Zawar, Rajasthan, ~1200 BCE)
- Famous for iron pillar at Mehrauli, Delhi (1600 years old, no rust!)
- Damascus steel — Indian origin
- Modern: Tata Steel, JSW, SAIL — world-leading
7. Common Ores
| Metal | Ore | Formula |
|---|---|---|
| Iron | Hematite, Magnetite | Fe₂O₃, Fe₃O₄ |
| Aluminium | Bauxite | Al₂O₃·2H₂O |
| Copper | Chalcopyrite | CuFeS₂ |
| Zinc | Zinc blende | ZnS |
| Lead | Galena | PbS |
| Mercury | Cinnabar | HgS |
| Silver | Argentite | Ag₂S |
8. Corrosion (Detailed)
What is Corrosion?
Slow eating away of metals due to action of air, moisture, chemicals.
Examples
- Rusting of iron (Fe₂O₃·xH₂O — reddish-brown)
- Tarnishing of silver (Ag₂S — black, by sulphur in air)
- Greening of copper (CuCO₃·Cu(OH)₂ — basic copper carbonate)
Prevention
- Painting
- Greasing/oiling
- Galvanisation (zinc coating — protects iron)
- Electroplating (silver/chromium plating)
- Alloying (mixing metals — stainless steel = Fe + Cr + Ni)
- Sacrificial protection (magnesium block on iron)
9. Worked Examples
Example 1: Reactivity
Can Cu displace Zn from ZnSO₄?
- NO. In activity series, Zn > Cu.
- Only Zn can displace Cu (from CuSO₄), not vice versa.
Example 2: Identification
A non-metal liquid at room temperature.
- BROMINE (Br₂). Only non-metal liquid at room temp.
Example 3: Property
Why are wires made of copper?
- Cu is excellent CONDUCTOR of electricity. Also DUCTILE (can be drawn into thin wires).
Example 4: Ionic Formation
How does magnesium chloride form?
- Mg loses 2 e⁻ → Mg²⁺
- Each Cl gains 1 e⁻ → Cl⁻
- Need 2 Cl⁻ per Mg²⁺ → MgCl₂
Example 5: Reduction Method
Why is aluminium extracted by electrolysis, not by reduction with carbon?
- Al is HIGH in reactivity series. C cannot reduce it.
- Electrolysis is needed for highly reactive metals.
10. Common Mistakes
-
All metals are solids
- Mercury (Hg) is LIQUID at room temperature.
-
Non-metals don't conduct
- GRAPHITE (form of carbon) conducts electricity.
-
Activity series memorisation
- K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au
-
Wrong oxide nature
- METAL OXIDES are BASIC. NON-METAL OXIDES are ACIDIC.
-
Ionic compounds conduct in solid state
- NO. They conduct only when MOLTEN or DISSOLVED.
11. Indian Heritage
Ancient Metallurgy
- Iron Pillar at Mehrauli (Delhi, ~4th century CE) — pure iron, no rust in 1600 years!
- Damascus steel (wootz steel from South India) — legendary for sharp blades
- Brass and bronze widely used in temple bells, coins
- Zinc smelting in Zawar (Rajasthan) ~1200 BCE — earliest in world
Modern
- India is #2 steel producer (2024)
- Major iron ore exports (Odisha, Karnataka)
- Hindalco (aluminium), Vedanta major companies
12. Conclusion
Metals and Non-metals are FUNDAMENTAL CHEMISTRY:
- Properties differ (lustrous vs dull, conducting vs not)
- Reactions with O₂, H₂O, acids
- Reactivity Series predicts behaviour
- Metallurgy turns ores into useful metals
- Indian heritage in metallurgy is rich
Master:
- Properties (physical and chemical)
- Activity series
- Common reactions
- Extraction methods
- Common ores
This is HIGH-MARK chapter. Practice 15+ problems.
Metals built our civilisation. Understanding them is understanding modern life.
