Metals and Non-metals – Study module with Revision Notes
CBSE Class 10 • Chemistry — Chapter 3: Metals and Non-metals
Comprehensive Study Module & Revision Notes — strictly NCERT-aligned and ideal for CBSE Class 10 board exam preparation.
Overview & Learning Objectives
Overview: This module covers physical and chemical behaviour of metals and non-metals, reaction patterns (with oxygen, water, acids), the reactivity series, important extraction processes, corrosion and practical applications. Equations are balanced and written using correct scientific notation (use of <sub>/<sup>).
Learning objectives
- Distinguish metals and non-metals by physical and chemical properties.
- Predict products of reactions: metal + oxygen, metal + water, metal + acid.
- Understand the reactivity series and displacement reactions.
- Describe how common metals are extracted from ores (conceptual).
- Explain corrosion and methods of prevention.
- Apply quick tests and write balanced chemical equations.
Physical & Chemical Properties — Metals vs Non-metals
Physical properties (Metals)
- Shiny (lustre), generally solids at room temperature (except Hg).
- Good conductors of heat and electricity.
- Malleable (can be hammered into sheets) and ductile (drawn into wires).
- High melting & boiling points (varies).
- Usually dense and sonorous.
Physical properties (Non-metals)
- No metallic lustre (dull), many are gases or brittle solids (e.g., sulphur).
- Poor conductors of heat and electricity (except graphite).
- Non-malleable, non-ductile; low density and low melting points (varies).
Chemical properties — typical reactions
| Reaction type | Metals (example) | Non-metals (example) |
|---|---|---|
| With oxygen | 2 Mg + O2 → 2 MgO (basic oxide) | S + O2 → SO2 (acidic oxide) |
| With water | 2 Na + 2 H2O → 2 NaOH + H2 (reactive metals) | Non-metals typically do not liberate H2 with water |
| With acids | Zn + 2 HCl → ZnCl2 + H2 (displacement of H2) | Non-metals often form molecular acids/oxides (e.g., P → H3PO4 in complex reactions) |
| Salt formation | Metal oxide + acid → salt + water (Na2O + 2 HCl → 2 NaCl + H2O) | Non-metal oxides often give acids with water (SO2 + H2O → H2SO3) |
Reactivity Series & Displacement Reactions
Reactivity series (common metals, most reactive → least):
K > Na > Ca > Mg > Al > Zn > Fe > Sn > Pb > (H) > Cu > Ag > Au
Rules & uses
- A metal can displace another metal from its salt solution if it is higher in the series. Example: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s).
- Hydrogen sits between Pb and Cu: metals above hydrogen displace H2 from acids.
Example — Predict & write equation
Will iron displace copper from copper sulfate? Yes, because Fe is above Cu: Fe + CuSO4 → FeSO4 + Cu.
Extraction of Metals — Basic Concepts
Most metals occur as ores (oxides, sulfides, carbonates). General steps: concentration of ore → conversion to oxide (if sulfide) by roasting → reduction (by carbon or other agents) → purification/refining.
Important processes (brief)
- Concentration: remove gangue by physical methods (washing, magnetic separation).
- Roasting: heating sulfide ores in air to convert to oxide: 2 ZnS + 3 O2 → 2 ZnO + 2 SO2.
- Calcination: heating carbonate ores to remove CO2, e.g., CaCO3 → CaO + CO2.
- Reduction: obtaining metal from oxide. Example: Fe2O3 + 3 CO → 2 Fe + 3 CO2 (in blast furnace). Less reactive metals (Cu, Ag) may be obtained by heating oxides directly.
Smelting (iron example)
In blast furnace: reduction of Fe2O3 / Fe3O4 using CO and coke → molten iron; impurities removed as slag (CaSiO3).
Corrosion & Prevention
Corrosion is electrochemical oxidation of metals (especially iron) in presence of moisture and oxygen forming rust (hydrated iron(III) oxide):
4 Fe + 3 O2 + x H2O → 2 Fe2O3·x H2O (rust)
Methods to prevent corrosion
- Paint/coatings to exclude air and moisture.
- Galvanisation — coating with zinc; zinc acts sacrificially.
- Alloying — stainless steel (Fe + Cr) forms protective oxide layer.
- Cathodic protection — attach more reactive metal (e.g., Mg anodes) to corrode preferentially.
Important Salts & Uses (Quick Reference)
| Salt | Formula | Uses |
|---|---|---|
| Common salt | NaCl | Food, chemical industry |
| Washing soda | Na2CO3 | Water softening, glass |
| Plaster of Paris | CaSO4·½H2O | Plaster casts, building |
| Bleaching powder | CaOCl2 | Disinfectant, bleaching |
| Sodium nitrate | NaNO3 | Fertilizers (oxidiser) |
Laboratory Tests & Practical Tips
Gas tests
- Hydrogen (H2): 'pop' with burning splint (ignition test).
- Oxygen (O2): glowing splint relights (supports combustion).
- Carbon dioxide (CO2): turns limewater (Ca(OH)2) milky (CaCO3 precipitate).
Tests for metal ions (qualitative)
- Copper(II) (Cu2+): blue solution (CuSO4), Cu(OH)2 blue precipitate with NaOH.
- Iron(II) (Fe2+): pale green; with NaOH gives green precipitate (Fe(OH)2), which on standing turns brown due to oxidation to Fe(OH)3 (brown).
- Silver (Ag+): AgNO3 + Cl− → AgCl(s) white precipitate.
Solved Example (Stoichiometry)
Q: 50 g of zinc reacts with excess hydrochloric acid. How many litres of H2 (at STP) will be produced? (Atomic masses: Zn = 65.4; 1 mol gas at STP = 22.4 L)
Solution: Reaction: Zn + 2 HCl → ZnCl2 + H2.
Moles of Zn = 50 / 65.4 ≈ 0.764 mol. From equation 1 mol Zn → 1 mol H2. So H2 moles = 0.764 mol. Volume at STP = 0.764 × 22.4 ≈ 17.12 L.
Answer: ≈ 17.1 L of H2.
Quick Revision Checklist & Exam Tips
- Memorise the reactivity series order & key examples.
- Practice balancing equations — atoms and charge must match.
- Know qualitative gas tests and precipitate tests (limewater, pop test, AgCl formation).
- Remember that changing subscripts changes identity — use coefficients only.
- Learn extraction steps conceptually (concentration, roasting/calcination, reduction, refinement).
- Understand corrosion mechanisms and prevention — be ready to suggest methods.
- Write neat balanced equations for reactions of metals with O2, H2O, acids, and salts.
Practice Questions (Short)
- Write the equation when magnesium burns in air. Identify the oxide formed.
- Explain why copper does not displace zinc from zinc sulfate.
- Give one method to prevent rusting of iron used for outdoor railings.
- Describe what happens when sodium is dropped into water (equation & observation).
- Balance and name the type: Fe + O2 → Fe2O3.