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📥 Download PDF (Free)Metals and Non-metals is Chapter 3 of CBSE Class 10 Science. This chapter explores the physical and chemical properties of metals and non-metals, how metals react with various substances, and how metals are extracted from their ores through metallurgy. It also covers corrosion and its prevention.
This is an important chapter for board exams - expect 5–8 marks. Reactivity series, extraction of metals, and ionic bond formation are the most frequently tested topics.
Key Concepts
1. Physical Properties of Metals and Non-metals
| Property | Metals | Non-metals |
|---|---|---|
| State at room temperature | Solid (except mercury - liquid) | Solid, liquid (bromine), or gas (oxygen, nitrogen) |
| Lustre (shine) | Shiny (lustrous) | Dull (non-lustrous), except iodine and diamond |
| Malleability (can be beaten into sheets) | Yes - gold and silver are most malleable | No - they are brittle |
| Ductility (can be drawn into wires) | Yes - gold is most ductile | No |
| Conductivity (heat and electricity) | Good conductors - silver is the best | Poor conductors (insulators), except graphite |
| Sonorous (produce sound when struck) | Yes - used in bells | No |
| Melting and boiling point | Generally high (except gallium, caesium) | Generally low |
| Density | Generally high | Generally low |
| Hardness | Generally hard (except sodium, potassium - cut with knife) | Generally soft (except diamond - hardest natural substance) |
Exceptions to remember:
- Mercury is a metal but is liquid at room temperature
- Sodium and potassium are soft metals - can be cut with a knife
- Diamond (a non-metal, form of carbon) is the hardest natural substance
- Graphite (non-metal) is a good conductor of electricity
- Iodine (non-metal) has a lustrous (shiny) appearance
2. Chemical Properties of Metals
a) Reaction with Oxygen (Burning in Air)
Metals react with oxygen to form metal oxides, which are generally basic in nature.
Metal + Oxygen → Metal Oxide
- 2Mg + O₂ → 2MgO (magnesium burns with a bright white flame)
- 4Al + 3O₂ → 2Al₂O₃
- 2Cu + O₂ → 2CuO (copper forms black copper oxide on heating)
Amphoteric oxides: Some metal oxides react with both acids and bases - e.g., Al₂O₃ and ZnO.
- Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O (acts as base)
- Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O (acts as acid)
b) Reaction with Water
| Metal | Reaction with water | Product |
|---|---|---|
| Sodium (Na), Potassium (K) | React vigorously with cold water - catch fire | Metal hydroxide + H₂ |
| Calcium (Ca) | Reacts with cold water - less vigorous | Ca(OH)₂ + H₂ (floats) |
| Magnesium (Mg) | Reacts slowly with cold water; fast with hot water/steam | Mg(OH)₂ or MgO + H₂ |
| Aluminium (Al), Iron (Fe), Zinc (Zn) | React only with steam (not cold/hot water) | Metal oxide + H₂ |
| Copper (Cu), Silver (Ag), Gold (Au) | Do NOT react with water at all | - |
Na and K are stored in kerosene oil to prevent reaction with moisture in air.
c) Reaction with Dilute Acids
Metal + Dilute acid → Salt + Hydrogen gas
- Zn + H₂SO₄ → ZnSO₄ + H₂↑
- Fe + 2HCl → FeCl₂ + H₂↑
- 2Na + 2HCl → 2NaCl + H₂↑
Important: Copper (Cu), Silver (Ag), and Gold (Au) do NOT react with dilute acids - they are below hydrogen in the reactivity series.
Note: Hydrogen gas is tested by bringing a burning splint near it - it burns with a “pop” sound.
d) Reaction with Salt Solutions (Displacement Reactions)
A more reactive metal displaces a less reactive metal from its salt solution.
- Fe + CuSO₄ → FeSO₄ + Cu (iron displaces copper - blue solution turns green)
- Zn + CuSO₄ → ZnSO₄ + Cu
- Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag (copper displaces silver)
- Cu + FeSO₄ → No reaction (copper is less reactive than iron)
3. The Reactivity Series
The reactivity series is an arrangement of metals in decreasing order of their reactivity:
K > Na > Ca > Mg > Al > Zn > Fe > Ni > Sn > Pb > (H) > Cu > Hg > Ag > Au > Pt
Memory trick: Kindly Note Calcium Magnesium Aluminium Zinc Iron Nickel Tin Lead (Hydrogen) Copper Mercury Silver Gold Platinum
Key points:
- Metals above hydrogen in the series displace hydrogen from dilute acids
- Metals below hydrogen (Cu, Ag, Au, Pt) do NOT react with dilute acids
- A metal can displace any metal below it in the series from its salt solution
- More reactive metals are harder to extract from their ores
4. Chemical Properties of Non-metals
a) Reaction with Oxygen
Non-metals react with oxygen to form non-metal oxides, which are acidic in nature.
- C + O₂ → CO₂ (acidic - turns lime water milky)
- S + O₂ → SO₂ (acidic - causes acid rain)
b) Reaction with Water
Non-metals generally do NOT react with water.
c) Reaction with Dilute Acids
Non-metals do NOT react with dilute acids (they cannot displace hydrogen).
5. Ionic Bonds - How Metals and Non-metals React with Each Other
Metals react with non-metals by transferring electrons to form ionic compounds (also called electrovalent compounds).
- Metals lose electrons → become positively charged ions (cations)
- Non-metals gain electrons → become negatively charged ions (anions)
- The electrostatic attraction between cations and anions holds the compound together - this is an ionic bond
Example - Formation of NaCl (sodium chloride):
- Na (2,8,1) loses 1 electron → Na⁺ (2,8) - achieves noble gas configuration
- Cl (2,8,7) gains 1 electron → Cl⁻ (2,8,8) - achieves noble gas configuration
- Na⁺ and Cl⁻ are held together by strong electrostatic force
Example - Formation of MgCl₂:
- Mg (2,8,2) loses 2 electrons → Mg²⁺ (2,8)
- Each Cl (2,8,7) gains 1 electron → Cl⁻ (2,8,8)
- One Mg²⁺ needs two Cl⁻ ions → MgCl₂
Properties of Ionic Compounds
| Property | Explanation |
|---|---|
| High melting and boiling points | Strong electrostatic force between ions requires a lot of energy to break |
| Solid at room temperature | Ions are tightly packed in a regular crystal lattice |
| Conduct electricity when dissolved in water or molten | Ions become free to move and carry charge |
| Do NOT conduct electricity in solid state | Ions are fixed in position - cannot move |
| Soluble in water | Water molecules can separate the ions |
| Insoluble in organic solvents (petrol, kerosene) | These solvents cannot break ionic bonds |
6. Occurrence and Extraction of Metals
How Metals Occur in Nature
- Native/Free state: Unreactive metals like gold, silver, and platinum are found as pure metals in nature
- Combined state: Most metals are found as compounds (ores) - usually as oxides, sulphides, or carbonates
Mineral vs Ore: A mineral is any naturally occurring compound of a metal. An ore is a mineral from which the metal can be profitably extracted.
Common Ores
| Metal | Ore | Formula |
|---|---|---|
| Aluminium | Bauxite | Al₂O₃·2H₂O |
| Iron | Haematite | Fe₂O₃ |
| Zinc | Zinc blende (Sphalerite) | ZnS |
| Copper | Copper pyrites | CuFeS₂ |
| Sodium | Rock salt | NaCl |
Steps of Extraction
Step 1 - Enrichment of ore (Concentration): Remove impurities (gangue/matrix) from the ore.
Step 2 - Conversion to metal oxide:
- Carbonate ores → Calcination (strong heating in absence of air): ZnCO₃ → ZnO + CO₂
- Sulphide ores → Roasting (heating in excess air): 2ZnS + 3O₂ → 2ZnO + 2SO₂
Step 3 - Reduction to metal: Method depends on the metal’s position in the reactivity series.
| Position in Reactivity Series | Metals | Extraction Method |
|---|---|---|
| Top (highly reactive) | K, Na, Ca, Mg, Al | Electrolytic reduction (electrolysis of molten ore) |
| Middle (moderately reactive) | Zn, Fe, Ni, Sn, Pb | Reduction with carbon (coke): ZnO + C → Zn + CO |
| Bottom (least reactive) | Cu, Hg, Ag, Au | Heating alone or self-reduction: 2HgS + 3O₂ → 2HgO + 2SO₂, then 2HgO → 2Hg + O₂ |
Thermite reaction: Highly reactive metals like aluminium can reduce less reactive metal oxides. This is used in welding railway tracks:
Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + Heat (extremely exothermic)
Step 4 - Refining (Purification)
The most common method is electrolytic refining:
- Anode: Impure metal
- Cathode: Thin strip of pure metal
- Electrolyte: Solution of metal salt
- On passing current, pure metal deposits on the cathode; impurities settle as anode mud
7. Corrosion
Corrosion is the slow destruction of a metal by the action of air, moisture, and chemicals on its surface.
- Rusting of iron: Iron reacts with oxygen and moisture to form hydrated iron(III) oxide (rust): 4Fe + 3O₂ + xH₂O → 2Fe₂O₃·xH₂O
- Tarnishing of silver: Silver reacts with H₂S in air to form black silver sulphide (Ag₂S)
- Green coating on copper: Copper reacts with CO₂ and moisture to form green copper carbonate [CuCO₃·Cu(OH)₂]
Prevention of Corrosion
- Painting / Oiling / Greasing: Coating prevents air and moisture from reaching the metal
- Galvanisation: Coating iron with a layer of zinc - the most common method for iron
- Electroplating: Coating with another metal (e.g., tin, chromium) using electrolysis
- Alloying: Mixing with other metals to make it corrosion-resistant (e.g., stainless steel = iron + chromium + nickel + carbon)
8. Alloys
An alloy is a homogeneous mixture of a metal with one or more other metals or non-metals.
| Alloy | Composition | Use |
|---|---|---|
| Brass | Copper + Zinc | Utensils, decorations |
| Bronze | Copper + Tin | Statues, medals, coins |
| Stainless steel | Iron + Chromium + Nickel + Carbon | Utensils, surgical instruments |
| Solder | Lead + Tin | Welding electrical wires |
| Amalgam | Mercury + other metal | Dental fillings |
Why make alloys? Pure metals are often too soft. Alloying increases hardness, strength, and corrosion resistance. For example, pure gold (24 carat) is very soft - it is alloyed with silver or copper to make jewellery (22 carat = 22 parts gold, 2 parts other metal).
Important Definitions
| Term | Definition |
|---|---|
| Malleability | Property of metals to be beaten into thin sheets |
| Ductility | Property of metals to be drawn into thin wires |
| Sonorous | Property of metals to produce a ringing sound when struck |
| Reactivity series | Arrangement of metals in decreasing order of their chemical reactivity |
| Ionic bond | Bond formed by transfer of electrons from a metal to a non-metal |
| Mineral | Naturally occurring compound of a metal found in the earth’s crust |
| Ore | Mineral from which a metal can be extracted profitably |
| Gangue | Impurities (sand, clay, rock) present in an ore |
| Calcination | Heating an ore strongly in the absence of air (for carbonate ores) |
| Roasting | Heating an ore in excess of air (for sulphide ores) |
| Thermite reaction | Reaction between aluminium and iron oxide producing molten iron + intense heat |
| Corrosion | Slow destruction of a metal surface by air, moisture, and chemicals |
| Galvanisation | Coating iron with zinc to prevent rusting |
| Alloy | Homogeneous mixture of a metal with other metals or non-metals |
| Amalgam | Alloy of mercury with another metal |
Solved Examples (NCERT-Based)
Example 1
Why is sodium stored in kerosene oil?
Answer: Sodium is a highly reactive metal - it reacts vigorously with oxygen in air and even with moisture (water vapour). When exposed to air, it catches fire. Kerosene oil does not react with sodium and prevents contact with air and moisture, keeping it safe.
Example 2
An iron nail is dipped in copper sulphate solution. What changes do you observe? Why?
Answer: The blue colour of CuSO₄ solution fades and turns green (FeSO₄ forms). A reddish-brown deposit of copper appears on the iron nail. This happens because iron is more reactive than copper (higher in the reactivity series), so it displaces copper: Fe + CuSO₄ → FeSO₄ + Cu
Example 3
Why does aluminium not corrode even though it is a reactive metal?
Answer: Aluminium forms a thin, tough layer of aluminium oxide (Al₂O₃) on its surface when exposed to air. This oxide layer is very stable and prevents further reaction of the metal with air and moisture. So even though aluminium is reactive, its oxide layer protects it from corrosion.
Example 4
Explain why ionic compounds have high melting points but do not conduct electricity in the solid state.
Answer: Ionic compounds consist of positive and negative ions held together by very strong electrostatic forces of attraction. Breaking these bonds requires a large amount of energy, hence the high melting points. In the solid state, ions are fixed in a rigid crystal lattice and cannot move - so they cannot carry electric charge. When melted or dissolved in water, the ions become free to move and can conduct electricity.
Important Questions for Board Exams
1-Mark Questions
- Name a metal that is liquid at room temperature.
- What is the nature of metal oxides - acidic or basic?
- Why is gold found in the free state in nature?
- Name the ore of aluminium.
- What is an alloy? Give one example.
2-Mark Questions
- Write the electron dot structure for the formation of MgCl₂.
- What is the difference between calcination and roasting?
- Why are food cans coated with tin and not zinc?
- Name two metals that can displace hydrogen from dilute acids and two that cannot.
- What is galvanisation? Why is it done?
3-Mark Questions
- Explain the extraction of metals of medium reactivity from their sulphide ores with an example.
- What are amphoteric oxides? Give two examples with reactions.
- What are ionic compounds? List four properties of ionic compounds.
- Describe the electrolytic refining of copper with a labelled diagram.
- Arrange the following metals in order of their reactivity: Al, Cu, Fe, Mg, Zn. Justify with one reaction.
5-Mark Questions
- Describe the steps involved in the extraction of metals from their ores. Explain how the method of extraction varies for metals of different reactivity.
- What is corrosion? Explain the rusting of iron. Describe four methods to prevent corrosion.
Quick Revision Points
- Metals: lustrous, malleable, ductile, sonorous, good conductors. Exceptions: mercury (liquid), Na/K (soft)
- Non-metals: dull, brittle, poor conductors. Exceptions: diamond (hard), graphite (conducts electricity), iodine (lustrous)
- Metal + O₂ → Metal oxide (basic); Non-metal + O₂ → Non-metal oxide (acidic)
- Amphoteric oxides: Al₂O₃ and ZnO react with both acids and bases
- Reactivity series: K > Na > Ca > Mg > Al > Zn > Fe > (H) > Cu > Ag > Au
- More reactive metal displaces less reactive metal from salt solution
- Ionic bond = transfer of electrons; ionic compounds have high MP, conduct when molten/dissolved
- Ore enrichment → Convert to oxide (calcination/roasting) → Reduce to metal → Refine
- Highly reactive metals: electrolysis | Medium: carbon reduction | Low: heating alone
- Thermite reaction: Fe₂O₃ + 2Al → 2Fe + Al₂O₃ (used in railway welding)
- Corrosion prevention: painting, oiling, galvanisation (zinc coating), electroplating, alloying
- Stainless steel = Fe + Cr + Ni + C; Brass = Cu + Zn; Bronze = Cu + Sn
- Pure gold (24K) is too soft - alloyed for jewellery (22K)
Previous Chapter: Chapter 2 - Acids, Bases and Salts
Next Chapter: Chapter 4 - Carbon and its Compounds
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Related Chapters in Class 10 Science
- Chemical Reactions and Equations Class 10 Notes
- Acids, Bases and Salts Class 10 Notes
- Carbon and its Compounds Class 10 Notes
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Weightage in Board Exams
Metals and Non-metals is Chapter 3 of the CBSE Class 10 Science syllabus and sits in Unit I, Chemical Substances – Nature and Behaviour, which carries 25 marks of the 80 mark theory paper. That unit is shared with Chemical Reactions and Equations, Acids Bases and Salts, and Carbon and its Compounds, so the marks are split across those chapters and CBSE does not publish a fixed per chapter figure.
The reactivity series and the extraction of metals carry the most marks, and ionic bonding and the properties of ionic compounds recur every year.
Frequently Asked Questions
What is the reactivity series of metals?
The reactivity series is a list of metals arranged in decreasing order of reactivity: potassium, sodium, calcium, magnesium, aluminium, zinc, iron, lead, hydrogen, copper, mercury, silver, gold and platinum. A metal higher in the series can displace any metal below it from its salt solution.
What are the physical properties of metals and non-metals?
Metals are usually lustrous, malleable, ductile, sonorous, and good conductors of heat and electricity, and most are solid at room temperature. Non-metals are usually dull, brittle when solid, and poor conductors. Exceptions matter in exams: mercury is a liquid metal, sodium is soft enough to cut, graphite is a non-metal that conducts, and iodine is a lustrous non-metal.
What is an ionic bond and how does it form?
An ionic bond forms when one atom transfers electrons to another so that both reach a stable noble gas configuration. The atom that loses electrons becomes a positive ion and the one that gains them becomes a negative ion, and the opposite charges attract. Sodium chloride forms this way, with sodium giving one electron to chlorine.
Why do ionic compounds have high melting points?
Ionic compounds are held together by strong electrostatic forces between oppositely charged ions throughout the crystal lattice. A large amount of heat energy is needed to overcome those forces, so ionic compounds have high melting and boiling points.
What are the main steps in the extraction of a metal from its ore?
First the ore is concentrated to remove impurities. Then the concentrated ore is converted to its oxide by calcination for carbonate ores or roasting for sulphide ores. The oxide is then reduced to the metal, usually with carbon for moderately reactive metals or by electrolysis for highly reactive ones. Finally the metal is refined.
What is corrosion and how can it be prevented?
Corrosion is the gradual eating away of a metal by air, moisture or chemicals in its surroundings, such as the rusting of iron, the black coating on silver and the green coating on copper. It can be prevented by painting, oiling, greasing, galvanising, anodising, chrome plating, or by making alloys such as stainless steel.
