In short: Metals and Non-Metals (Chapter 3) carries 7-8 marks in CBSE Class 10 Science. The chapter covers physical and chemical properties of metals and non-metals, the reactivity series, extraction of metals based on reactivity, and properties of ionic compounds. The reactivity series is the single most important concept — memorize it and you can answer most questions.
Physical Properties Comparison
| Property | Metals | Non-Metals |
|---|---|---|
| State | Solid (except mercury — liquid) | Solid, liquid, or gas |
| Lustre | Shiny | Dull (except iodine, diamond) |
| Malleability | Can be beaten into sheets | Brittle |
| Ductility | Can be drawn into wires | Not ductile |
| Conductivity | Good conductors of heat and electricity | Poor conductors (except graphite) |
| Sonorous | Produce sound when struck | Do not |
| Density | Generally high | Generally low |
| Melting point | Generally high | Generally low |
Exceptions to know:
- Mercury is a liquid metal
- Iodine is a lustrous non-metal
- Graphite conducts electricity (non-metal)
- Diamond is the hardest natural substance (non-metal)
- Sodium and potassium are soft metals (cut with a knife)
- Sodium and potassium have low density (float on water)
Chemical Properties of Metals
1. Reaction with Oxygen
Metal + Oxygen → Metal Oxide
- 4Na + O₂ → 2Na₂O (vigorous, bright yellow flame)
- 2Mg + O₂ → 2MgO (bright white flame)
- 4Al + 3O₂ → 2Al₂O₃ (aluminium oxide layer protects further reaction)
- 4Fe + 3O₂ → 2Fe₂O₃ (iron rust — slow reaction)
Metal oxides are basic in nature. They react with water to form bases.
2. Reaction with Water
| Metal | Reaction with water |
|---|---|
| Na, K | React vigorously with cold water → metal hydroxide + H₂ |
| Ca | Reacts with cold water (less vigorous) |
| Mg | Reacts with hot water |
| Al, Zn, Fe | React with steam only |
| Cu, Ag, Au | Do not react with water at all |
Key equations:
- 2Na + 2H₂O → 2NaOH + H₂↑
- Ca + 2H₂O → Ca(OH)₂ + H₂↑
- 2Al + 6H₂O → 2Al(OH)₃ + 3H₂↑ (with steam)
3. Reaction with Dilute Acids
Metal + Dilute acid → Salt + Hydrogen gas
- Zn + 2HCl → ZnCl₂ + H₂↑
- Fe + H₂SO₄ → FeSO₄ + H₂↑
- Cu, Ag, Au do not react with dilute acids (below hydrogen in reactivity series)
The Reactivity Series
Memorize this order (most to least reactive):
K > Na > Ca > Mg > Al > Zn > Fe > Ni > Sn > Pb > (H) > Cu > Hg > Ag > Au > Pt
Mnemonic: Kindly Never Call Me A Zebra In New Shiny Purple Hat Copper Horse Silver Gold Platinum
The position in the reactivity series determines:
- How a metal reacts with water and acids
- How it is extracted from its ore
- Whether it can displace another metal from its salt solution
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Extraction of Metals
The extraction method depends on the metal's position in the reactivity series:
Highly Reactive Metals (K, Na, Ca, Mg, Al)
Method: Electrolytic reduction (electrolysis of molten ore)
These metals are too reactive for carbon reduction. Example: Aluminium is extracted from bauxite by the Hall-Heroult process (electrolysis of molten Al₂O₃).
Moderately Reactive Metals (Zn, Fe, Pb, Cu)
Method: Reduction with carbon (coke)
- ZnO + C → Zn + CO
- Fe₂O₃ + 3C → 2Fe + 3CO (blast furnace for iron)
Steps: Ore → Concentration → Roasting/Calcination → Reduction → Refining
Roasting: Heating sulphide ore in air → metal oxide + SO₂
- 2ZnS + 3O₂ → 2ZnO + 2SO₂
Calcination: Heating carbonate ore → metal oxide + CO₂
- ZnCO₃ → ZnO + CO₂
Least Reactive Metals (Cu, Ag, Au, Pt)
Method: Found free in nature or extracted by simple heating
- 2HgS + 3O₂ → 2HgO + 2SO₂ (roasting)
- 2HgO → 2Hg + O₂ (heating)
Ionic Compounds
When metals react with non-metals, they form ionic compounds through electron transfer.
Formation of NaCl:
- Na (2,8,1) loses 1 electron → Na⁺ (2,8)
- Cl (2,8,7) gains 1 electron → Cl⁻ (2,8,8)
- Electrostatic attraction between Na⁺ and Cl⁻ = ionic bond
Properties of ionic compounds:
- High melting and boiling points (strong electrostatic forces)
- Soluble in water (polar solvent)
- Conduct electricity when dissolved in water or in molten state
- Do not conduct electricity in solid state (ions are fixed)
- Hard and brittle
Corrosion
Rusting of iron: 4Fe + 3O₂ + xH₂O → 2Fe₂O₃.xH₂O (hydrated iron oxide)
Rust is a brown, flaky substance that weakens iron.
Prevention methods:
- Painting, oiling, greasing (blocks contact with air/moisture)
- Galvanization (coating with zinc)
- Electroplating (coating with another metal)
- Alloying (stainless steel = iron + chromium + nickel)
Board Exam Important Questions
- Arrange the following metals in decreasing order of reactivity: Cu, Fe, Na, Zn, Mg. (2 marks)
- Why is aluminium extracted by electrolysis and not by carbon reduction? (2 marks)
- Explain the extraction of zinc from zinc blende. (3-5 marks)
- What are ionic compounds? List their 4 properties. (3 marks)
- What is corrosion? How can rusting of iron be prevented? (3 marks)
- A metal X reacts with dilute HCl to give salt and hydrogen. It also reacts with water. Identify the metal. (2 marks)
- Write the electron dot structure of NaCl. (2 marks)
For all chemical equations, see the Science formulas list. For chapter-wise marks, see the Science weightage guide.
Frequently Asked Questions
How many marks does Metals and Non-Metals carry?
7-8 marks as part of the 25-mark "Chemical Substances" unit.
Is the reactivity series important?
Essential. It determines extraction methods, displacement reactions, and reaction predictions. Memorize it completely.
What is the most asked question from this chapter?
"Explain the extraction of a metal from its ore" (3-5 marks) and "Properties of ionic compounds" (3 marks) are the most frequently asked.
Do I need to know electron dot structures?
Yes. Drawing the formation of NaCl or MgCl₂ using electron dot structures is a 2-3 mark question.
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