CBSE Class 10 · Science · board exam 2027
Chapter 3: Metals and Non-metals — notes
The chapter’s 10 parts in the book’s order — the first idea of each and the points Medha Ma’am writes on the board — and the summary at the end. The full lesson and a check question for each part are in the app.
1. Physical properties of metals
Take a piece of iron, copper or aluminium and rub its surface with sandpaper.
- • 1. Metallic lustre: a pure metal has a shining surface
- • 2. Hardness: metals are generally hard
- • 3. Malleability: can be beaten into thin sheets (most: gold, silver)
- • 4. Ductility: can be drawn into thin wires (most: gold)
- • 1 g of gold → a wire about 2 km long
- • Activity: metals conduct heat
- • Observed: the wax melts and the pin falls; the wire does not melt
- • Conclusion: metals are good conductors of heat with high melting points
- • Best conductors of heat: silver, copper
- • Comparatively poor: lead, mercury
- • 5. Electrical conductivity: the bulb glows, metals conduct electricity
- • Wires coated with PVC: a poor conductor, protects from shocks
- • 6. Sonority: metals ring when struck (school bells)
2. Non-metals and the exceptions
The non-metals.
- • Non-metals: carbon, sulphur, iodine, oxygen, hydrogen
- • Solids or gases; the only liquid non-metal: bromine
- • No lustre, brittle, poor conductors of heat and electricity
- • Exceptions among metals
- • Mercury: a liquid metal at room temperature
- • Sodium, potassium: soft, cut with a knife, low melting points
- • Gallium, caesium: melt on the palm
- • Exceptions among non-metals
- • Iodine: a non-metal, but lustrous
- • Diamond (allotrope of carbon): the hardest natural substance
- • Graphite (allotrope of carbon): conducts electricity
- • | Property | Metals | Non-metals |
- • | State | Solid (mercury liquid) | Solid, liquid (bromine) or gas |
- • | Lustre | Lustrous | Not lustrous (iodine is) |
- • | On beating | Malleable | Brittle |
- • | Wires | Ductile | Not ductile |
- • | Conduction | Good conductors | Poor (graphite conducts) |
- • Physical properties alone do not classify clearly → chemical properties
3. Reaction of metals with oxygen
Almost all metals combine with oxygen to form metal oxides.
- • Metal + Oxygen → Metal oxide
- • Copper + Oxygen → Copper(II) oxide
- • Cu + O₂ → CuO (unbalanced)
- • | Element | Left | Right |
- • | O | 2 | 1 → 2CuO → 2 |
- • | Cu | 1 → 2 | 2 |
- • 2Cu(s) + O₂(g) → Δ 2CuO(s)
- • Copper(II) oxide: black
- • Al + O₂ → Al₂O₃ (unbalanced)
- • O: left 2, right 3 → LCM 6 → 3O₂ and 2Al₂O₃
- • Al: right 2 × 2 = 4 → 4Al on the left
- • 4Al(s) + 3O₂(g) → 2Al₂O₃(s)
- • Amphoteric oxides: react with both acids and bases to give salt and water
- • With an acid:
- • Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
- • With a base (sodium aluminate forms):
- • Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
- • Examples: Al₂O₃, ZnO
- • Al: 2 → 2AlCl₃; Cl: 6 → 6HCl; H: 6 → 3H₂O; O: 3 = 3 ✓
- • Na₂O(s) + H₂O(l) → 2NaOH(aq)
- • K₂O(s) + H₂O(l) → 2KOH(aq)
- • Alkalis: bases that dissolve in water (NaOH, KOH)
- • Sodium, potassium: catch fire in the open → kept in kerosene
- • Magnesium, aluminium, zinc, lead: protective oxide layer
- • Iron: filings burn in a flame; copper: black coat
- • Silver, gold: no reaction even at high temperature
- • Anodising: forming a thick oxide layer on aluminium
- • Aluminium = anode, electrolysed with dilute sulphuric acid
- • Oxygen at the anode → thicker Al₂O₃ layer → protection, can be dyed
4. Reaction of metals with water
Metals react with water to give a metal oxide and hydrogen gas.
- • Metal + Water → Metal oxide + Hydrogen
- • Metal oxide + Water → Metal hydroxide
- • Sodium + Water → Sodium hydroxide + Hydrogen + heat
- • Na + H₂O → NaOH + H₂ (unbalanced)
- • | Element | Left | Right |
- • | H | 2 → 2H₂O → 4 | 1 + 2 = 3 → 2NaOH + H₂ → 4 |
- • | O | 2 | 2 |
- • | Na | 1 → 2 | 2 |
- • 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g) + heat
- • 2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g) + heat
- • Ca(s) + 2H₂O(l) → Ca(OH)₂(aq) + H₂(g)
- • Less violent; calcium floats
- • Mg(s) + 2H₂O(l) → Mg(OH)₂(aq) + H₂(g)
- • Magnesium: only with hot water
- • Activity: action of steam on a metal
- • 2Al(s) + 3H₂O(g) → Al₂O₃(s) + 3H₂(g)
- • Zn(s) + H₂O(g) → ZnO(s) + H₂(g)
- • Fe + H₂O → Fe₃O₄ + H₂ (unbalanced)
- • Fe: 3 on the right → 3Fe; O: 4 → 4H₂O; H: 8 → 4H₂
- • 3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)
- • Lead, copper, silver, gold: no reaction with water
5. Reaction of metals with acids
Dilute acids.
- • Metal + Dilute acid → Salt + Hydrogen
- • Test: a burning candle near the gas → pop sound → hydrogen
- • Mg + HCl → MgCl₂ + H₂ (unbalanced)
- • Cl: left 1, right 2 → 2HCl; H: 2 = 2 ✓
- • Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)
- • Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)
- • Fe(s) + 2HCl(aq) → FeCl₂(aq) + H₂(g)
- • 2Al(s) + 6HCl(aq) → 2AlCl₃(aq) + 3H₂(g)
- • Reactivity: Mg > Al > Zn > Fe; copper: no reaction
- • Metal + nitric acid: hydrogen is generally not evolved
- • Reason: a strong oxidising agent, oxidises hydrogen to water
- • Exception: magnesium, manganese + very dilute nitric acid → hydrogen
- • Aqua regia: concentrated HCl and concentrated nitric acid, ratio 3 : 1
- • Dissolves even gold and platinum
6. Displacement reactions and the reactivity series
The figure, two test tubes.
- • Activity: displacement
- • A: iron nail + copper sulphate → brown coat on the nail, blue turns green
- • B: copper wire + iron sulphate → no change
- • Iron + Copper sulphate → Iron sulphate + Copper
- • Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)
- • Conclusion: iron is more reactive than copper
- • Metal A + salt solution of B → salt solution of A + Metal B
- • A displaces B ⇒ A is more reactive than B
- • Reactivity series: metals in decreasing order of reactivity
- • K > Na > Ca > Mg > Al > Zn > Fe > Pb > [H] > Cu > Hg > Ag > Au
- • Metals above hydrogen → displace hydrogen from dilute acids
- • Mg(s) + ZnSO₄(aq) → MgSO₄(aq) + Zn(s)
- • Cu + ZnSO₄ → no reaction (copper is below zinc)
7. How metals and non-metals react: ionic compounds
Noble gases have a completely filled outermost shell, an octet, so they hardly react.
- • Every element tends to attain a completely filled valence shell (octet)
- • Metals: 1, 2 or 3 valence electrons → lose them → cations
- • Non-metals: 5, 6 or 7 valence electrons → gain → anions
- • Na → Na⁺ + e⁻
- • Configuration: (2, 8, 1) to (2, 8)
- • Cl + e⁻ → Cl⁻
- • Configuration: (2, 8, 7) to (2, 8, 8)
- • Na⁺ + Cl⁻ → NaCl
- • Ionic (electrovalent) compounds: formed by the transfer of electrons from a metal to a non-metal
- • Strong electrostatic attraction between the cations and the anions
- • Mg → Mg²⁺ + 2e⁻
- • Configuration: (2, 8, 2) to (2, 8)
- • 2Cl + 2e⁻ → 2Cl⁻
- • Configuration: (2, 8, 7) to (2, 8, 8)
- • Mg²⁺ + 2Cl⁻ → MgCl₂
- • 1. Solid, somewhat hard, brittle: strong attraction between ions
- • 2. High melting and boiling points: much energy to break the attraction
- • | Compound | Melting point (K) | Boiling point (K) |
- • | NaCl | 1074 | 1686 |
- • | CaO | 2850 | 3120 |
- • 3. Soluble in water; insoluble in kerosene, petrol
- • 4. Conduct electricity when molten or in solution: the ions move
- • No conduction in the solid state: ions held in a rigid structure cannot move
8. Occurrence and extraction of metals
Metals are found in the earth's crust.
- • Minerals: elements or compounds occurring naturally in the earth's crust
- • Ores: minerals from which a metal can be extracted profitably
- • Gangue: impurities like soil and sand in the ore
- • Method of extraction depends on the position in the reactivity series
- • Gold, silver, platinum: found in the free state
- • Copper, silver: found both free and combined
- • 2HgS(s) + 3O₂(g) → Δ 2HgO(s) + 2SO₂(g)
- • | Hg | 2 | 2 | | S | 2 | 2 | | O | 6 | 2 + 4 = 6 |
- • 2HgO(s) → Δ 2Hg(l) + O₂(g)
- • 2Cu₂S(s) + 3O₂(g) → Δ 2Cu₂O(s) + 2SO₂(g)
- • 2Cu₂O(s) + Cu₂S(s) → Δ 6Cu(s) + SO₂(g)
- • Roasting: sulphide ore heated strongly in excess air
- • 2ZnS(s) + 3O₂(g) → Δ 2ZnO(s) + 2SO₂(g)
- • Calcination: carbonate ore heated strongly in limited air
- • ZnCO₃(s) → Δ ZnO(s) + CO₂(g)
- • ZnO(s) + C(s) → Δ Zn(s) + CO(g)
- • ZnO is reduced, C is oxidised
- • Thermit reaction (displacement): joining railway tracks
- • Fe₂O₃ + Al → Fe + Al₂O₃ (unbalanced)
- • Fe: 2 → 2Fe; Al: 2 → 2Al; O: 3 = 3 ✓
- • Fe₂O₃(s) + 2Al(s) → 2Fe(l) + Al₂O₃(s) + heat
- • 3MnO₂(s) + 4Al(s) → 3Mn(l) + 2Al₂O₃(s) + heat
- • Top metals: electrolytic reduction of molten compounds
- • Reason: more affinity for oxygen than carbon
- • At the cathode: Na⁺ + e⁻ → Na
- • At the anode: 2Cl⁻ → Cl₂ + 2e⁻
- • Electrolytic refining of copper
- • Anode (+): impure copper
- • Cathode (−): thin strip of pure copper
- • Electrolyte: acidified copper sulphate solution
- • At the anode: Cu → Cu²⁺ + 2e⁻
- • At the cathode: Cu²⁺ + 2e⁻ → Cu
- • Anode mud: insoluble impurities settling below the anode
9. Corrosion and its prevention
Silver articles turn black after some time, because silver reacts with sulphur in the air and forms a coating of silver sulphide.
- • Corrosion: a metal slowly attacked by moisture, air, acids
- • Silver: black coat (silver sulphide)
- • Copper: green coat (basic copper carbonate)
- • Iron: brown flaky coat (rust)
- • Activity: conditions for rusting
- • A: tap water + air
- • B: boiled water + oil layer (no air)
- • C: dry air over anhydrous calcium chloride (no water)
- • Observed: only the nails in A rust; none in B and C
- • Conclusion: rusting needs both air (oxygen) and water
- • Prevention: paint, oil, grease, galvanising, chrome plating, anodising, alloying
- • Galvanising: a thin coat of zinc on iron or steel
- • Protected even if the coat breaks: zinc is more reactive than iron
10. Alloys
Write the definition exactly.
- • Alloy: a homogeneous mixture of two or more metals, or of a metal and a non-metal
- • Making: melt the base metal → dissolve the others in fixed proportion → cool
- • Steel: iron + a little carbon (about 0.05%) → hard and strong
- • Stainless steel: iron + nickel + chromium (+ a little carbon) → does not rust
- • | Alloy | Constituents | Special point |
- • | Brass | copper + zinc | |
- • | Bronze | copper + tin | |
- • | Solder | lead + tin | low melting point, welds wires |
- • | Amalgam | mercury + another metal | |
- • Alloys: lower electrical conductivity and lower melting point than the pure metal
- • Pure gold = 24 carat (soft); jewellery: 22 carat
- • 22 parts gold + 2 parts silver or copper
- • 24 − 22 = 2
Summary
Very good! You learnt a lot today, so let us revise it once together. Metals are lustrous, malleable, ductile, sonorous and good conductors, with exceptions like mercury, sodium, iodine and graphite. Metals form basic oxides, and the oxides of aluminium and zinc are amphoteric. Metals give hydrogen with water and dilute acids, and displacement reactions gave us the reactivity series, potassium at the top and gold at the bottom. A metal gives electrons and a non-metal takes them, forming ionic compounds with high melting points that conduct only when molten or dissolved. Then extraction, roasting, calcination, reduction, electrolysis and refining, and finally corrosion and alloys. Write all of today's balanced equations once in your notebook without looking, and learn the reactivity series by heart. Today's homework is on your screen. If anything was not clear, press the Ask button and ask me. Done, you worked very well today!
AskMedha · Medha Ma’am — CBSE Class 10 Science, Chapter 3. Written from the textbook, checked twice.
Questions parents and students ask
- How do I get the "Metals and Non-metals" notes as a PDF?
- Press "Save as PDF" — the phone’s print sheet opens; choose "Save as PDF" there. The PDF holds the notes only.
- Where are these notes written from?
- From the chapter’s own textbook text, part by part, in the book’s own terms; a second, independent model then checked every part against the book. The full lesson, a check question for each part and the practice are in the AskMedha app.
The same preparation, with Medha Ma’am — on your phone
Every question of every chapter with its model answer, practice questions in the board’s own shapes, 60 minutes of class a day, written answers marked, a test every Sunday and a WhatsApp report to parents.
Medha Ma’am is an AI teacher, not a live tutor. Every answer is checked twice; a person takes responsibility.