Simply CBSE

Metals and Non-metals — Class 10 Science

Quick revision notes for exam preparation.

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📌 Key Points

  • Metals: lustrous, malleable, ductile, sonorous, good conductors. Exceptions: Na/K soft, Hg liquid, Ga/Cs low MP
  • Non-metals: dull, brittle, poor conductors. Exceptions: graphite conducts, diamond hardest, iodine lustrous
  • Metal + O₂ → Metal oxide (basic). Al₂O₃ and ZnO are amphoteric (react with both acid and base)
  • Metal + Water: Na/K (cold water, vigorous) > Ca (cold water) > Mg (hot water) > Fe/Zn (steam) > Cu/Ag/Au (no reaction)
  • Metal + Dilute acid → Salt + H₂. Metals below H in reactivity series (Cu, Ag, Au) do NOT react with dilute acids
  • Reactivity series: K > Na > Ca > Mg > Al > Zn > Fe > [H] > Cu > Hg > Ag > Au > Pt
  • Displacement: more reactive metal displaces less reactive from salt solution
  • Extraction — High reactivity (K–Al): electrolysis. Medium (Zn–Pb): carbon reduction. Low (Cu–Au): heating
  • Roasting: sulphide ore + air → oxide + SO₂. Calcination: carbonate ore (no air) → oxide + CO₂
  • Thermite reaction: Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat (railway track welding)
  • Ionic bond: electron transfer from metal to non-metal. Na(2,8,1) → Na⁺ + e⁻; Cl + e⁻ → Cl⁻
  • Ionic compounds: high MP, soluble in water, conduct when molten/dissolved (NOT solid), hard but brittle
  • Electrolytic refining: anode = impure, cathode = pure, electrolyte = metal salt solution, anode mud = impurities
  • Corrosion: rusting needs O₂ + H₂O. Silver → Ag₂S (black). Copper → CuCO₃ (green). Al₂O₃ layer is protective
  • Alloys: brass (Cu+Zn), bronze (Cu+Sn), stainless steel (Fe+Cr+Ni+C), solder (Pb+Sn). 22 carat gold for jewellery

📘 Important Definitions

Malleability
Property of metals to be beaten into thin sheets. Gold is the most malleable metal.
Ductility
Property of metals to be drawn into thin wires. Gold is the most ductile metal.
Reactivity Series
A list of metals arranged in decreasing order of their reactivity: K > Na > Ca > Mg > Al > Zn > Fe > [H] > Cu > Ag > Au.
Mineral
A naturally occurring substance containing a metal in combined form. Not all minerals are ores.
Ore
A mineral from which a metal can be extracted profitably. Example: bauxite (Al₂O₃·2H₂O) is an ore of aluminium.
Gangue
Impurities (sand, clay, rock) present in an ore that must be removed before extraction.
Roasting
Heating sulphide ore in excess air to convert it to oxide. Example: 2ZnS + 3O₂ → 2ZnO + 2SO₂.
Calcination
Heating carbonate ore in limited/no air to convert it to oxide. Example: ZnCO₃ → ZnO + CO₂.
Ionic Bond
Bond formed by transfer of electrons from metal to non-metal, creating oppositely charged ions held by electrostatic attraction.
Alloy
Homogeneous mixture of two or more metals, or a metal and a non-metal. Example: stainless steel (Fe+Cr+Ni+C).

🔢 Formulas & Laws

Na + Water

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

Vigorous, catches fire

Fe + Steam

3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)

Reacts with steam only

Roasting of ZnS

2ZnS + 3O₂ → 2ZnO + 2SO₂

Sulphide ore → oxide

Thermite reaction

Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat

Railway track welding

NaCl formation

Na → Na⁺ + e⁻; Cl + e⁻ → Cl⁻; Na⁺ + Cl⁻ → NaCl

Ionic bond by electron transfer

⚠️ Common Mistakes

✗ Wrong: All metals are hard and have high melting points

✓ Correct: Na and K are soft (cut with knife). Mercury is liquid. Gallium and caesium have very low melting points.

✗ Wrong: All non-metals are poor conductors

✓ Correct: Graphite is an excellent conductor of electricity. It is used in electrodes and pencil leads.

✗ Wrong: Confusing roasting and calcination

✓ Correct: Roasting = sulphide ore + air. Calcination = carbonate ore + no air. Different ores, different conditions.

✗ Wrong: Ionic compounds conduct electricity in solid state

✓ Correct: Ionic compounds conduct only when MOLTEN or in AQUEOUS SOLUTION — NOT in solid state (ions are fixed).

✗ Wrong: Copper can displace zinc from ZnSO₄

✓ Correct: Cu is BELOW Zn in the reactivity series. Only a MORE reactive metal can displace a LESS reactive one.

📝 Exam Focus

These questions are frequently asked in CBSE exams:

Chemical properties of metals (reactions with O₂, H₂O, acids, salts)
5m★★★
Reactivity series and displacement reactions
3m★★★
Extraction of metals based on reactivity (roasting, calcination, reduction)
5m★★★
Ionic bond formation (NaCl, MgCl₂) with electron configuration
3m★★★
Properties of ionic compounds
3m★★★
Alloy compositions (brass, bronze, stainless steel, solder)
2m★★
Corrosion prevention methods
3m★★
Thermite reaction and electrolytic refining
3m★★

Diagram to practice: Practice drawing: reactivity series chart, electrolytic refining setup (anode/cathode/electrolyte), electron dot structures for NaCl and MgCl₂ formation

🎯 Last-Minute Recall

Close your eyes and try to recall: Key definitions, formulas, and 3 common mistakes. If you can recall 80% without looking, you're exam-ready!