📘 Chapter 3: Metals and Non-metals – CBSE Class 10 Science

🔷 I. Physical Properties

🔷 II. Chemical Properties of Metals

1. Reaction with Oxygen

• Forms metal oxides
  Example:
  4Na + O₂ → 2Na₂O
  2Mg + O₂ → 2MgO

Metal oxides are generally basic in nature. Some (e.g., Al₂O₃, ZnO) are amphoteric.

2. Reaction with Water

• Forms metal hydroxide + hydrogen gas
  Example:
  2Na + 2H₂O → 2NaOH + H₂↑
  Mg + H₂O → Mg(OH)₂ + H₂ (slow with cold water, fast with hot)

3. Reaction with Acids

• Forms salt + hydrogen gas
  Example:
  Zn + 2HCl → ZnCl₂ + H₂↑
  Cu does not react with dilute acids.

4. Reaction with Salt Solutions

• More reactive metal displaces less reactive one
  Example:
  Fe + CuSO₄ → FeSO₄ + Cu (displacement reaction)

🔷 III. Chemical Properties of Non-Metals

• Do not react with dilute acids
• React with oxygen to form acidic or neutral oxides
  Example: C + O₂ → CO₂
• Tend to gain electrons to form anions

🔷 IV. Uses of Metals and Non-Metals

Metals:

• Cu, Al: electrical wiring
• Fe: tools, machines
• Zn: galvanization

Non-Metals:

• O₂: respiration
• N₂: fertilizer
• Cl₂: water purification
• C (graphite): electrodes

🔷 V. Reactivity Series

• Ranks metals from most reactive (K) to least reactive (Au)
• Helps predict displacement reactions

Reactivity Order (Top 5):
K > Na > Ca > Mg > Al

🔷 VI. Ionic Bond Formation

• Metals lose electrons → form cations
• Non-metals gain electrons → form anions
• Electrostatic attraction between ions = ionic bond

Example:
Na (1 electron in outer shell) + Cl (7 electrons) → NaCl

🔷 VII. Metallurgy

Steps of extraction:

1. Concentration: Removing impurities from ore
2. Reduction: Extracting metal from concentrated ore
3. Refining: Purifying the extracted metal

Types of Ores:

• Oxide ores: Bauxite (Al₂O₃), Hematite (Fe₂O₃)
• Sulphide ores: Zinc blende (ZnS)

Methods:

• For highly reactive: Electrolytic reduction (e.g., Na, K, Al)
• For moderately reactive: Roasting/Calcination followed by reduction
• For less reactive: Direct reduction (e.g., Hg, Cu)

🔷 VIII. Corrosion

Definition: Gradual destruction of metal by chemical/environmental reaction.

Example:
Iron + Oxygen + Moisture → Rust (Fe₂O₃·xH₂O)

Prevention:

• Painting
• Oiling/Greasing
• Galvanization (Zn coating)

🔷 IX. Alloys

Definition: Homogeneous mixture of two or more metals or metal + non-metal.

Examples:

• Brass = Copper + Zinc
• Bronze = Copper + Tin
• Steel = Iron + Carbon

Alloys are stronger, corrosion-resistant, and have lower melting points.

✅ Multiple Choice Questions (MCQs) with Answers

🔹 Conceptual MCQs

1. Which metal is liquid at room temperature?
   a) Zinc b) Mercury c) Lead d) Copper
   ✅ Answer: b
2. Which is the most ductile metal?
   a) Iron b) Copper c) Aluminium d) Gold
   ✅ Answer: d
3. Which of the following is an amphoteric oxide?
   a) MgO b) Al₂O₃ c) CO₂ d) SO₂
   ✅ Answer: b
4. Which of the following metals does not react with dilute HCl?
   a) Mg b) Fe c) Cu d) Zn
   ✅ Answer: c

🔹 Reaction-Based MCQs

5. Which gas is evolved when Zn reacts with HCl?
   a) Oxygen b) Nitrogen c) Hydrogen d) Carbon dioxide
   ✅ Answer: c
6. Which of the following will displace Cu from CuSO₄ solution?
   a) Ag b) Fe c) Hg d) Au
   ✅ Answer: b
7. Which of the following methods is used to extract highly reactive metals?
   a) Roasting b) Calcination c) Electrolysis d) Smelting
   ✅ Answer: c

🔹 Assertion-Reason Type

8. Assertion (A): NaCl is an ionic compound.
    Reason (R): It is formed by sharing of electrons.
   a) A and R both correct, R explains A
   b) A is correct, R is incorrect
   c) Both are incorrect
   d) A is incorrect, R is correct
   ✅ Answer: b
9. Assertion (A): Aluminium does not corrode easily.
    Reason (R): It forms a protective oxide layer on its surface.
   ✅ Answer: a

🔹 HOTS MCQs

10. Which of the following will float in water?
    a) Iron b) Lead c) Sodium d) Copper
    ✅ Answer: c
11. What is the formula of rust?
    a) Fe₂O₃ b) FeO c) Fe₃O₄ d) Fe₂O₃·xH₂O
    ✅ Answer: d
12. Which is not a property of metals?
    a) Sonorous
    b) Lustrous
    c) Brittle
    d) Malleable
    ✅ Answer: c