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Metals and Non-metals

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Chapter Notes

Overview
This chapter builds on Class IX knowledge to systematically classify elements into metals and non-metals based on their physical and chemical properties. It explains why metals are good conductors, malleable, ductile, and sonorous, while non-metals are generally brittle and poor conductors. The central idea is that metals achieve stability by losing electrons to form positive ions and basic oxides, whereas non-metals gain electrons to form negative ions and acidic oxides. A student must walk away understanding the reactivity series, how it governs reactions with oxygen, water, acids, and salt solutions, and how this determines extraction methods and everyday applications like corrosion prevention and alloying.
Key Concepts (19)
Metallic lustre
The shining surface of metals in their pure state.
e.g. A freshly cut piece of magnesium or a clean copper wire shines brightly.
Malleability
The property of metals by which they can be beaten into thin sheets.
e.g. Gold and silver are the most malleable metals; used to make gold leaves.
Ductility
The ability of metals to be drawn into thin wires.
e.g. Gold is the most ductile metal; a wire of about 2 km length can be drawn from one gram of gold.
Sonority
The property of metals to produce a sound when struck on a hard surface.
e.g. School bells are made of metals because they are sonorous.
Amphoteric oxides
Metal oxides which react with both acids and bases to produce salts and water.
e.g. Aluminium oxide (Al₂O₃) and zinc oxide (ZnO) are amphoteric oxides.
Reactivity series
A list of metals arranged in the order of their decreasing reactivity.
e.g. Potassium is the most reactive, gold is the least reactive.
Ionic compounds
Compounds formed by the transfer of electrons from a metal to a non-metal, also called electrovalent compounds.
e.g. Sodium chloride (NaCl) and magnesium chloride (MgCl₂) are ionic compounds.
Mineral
Elements or compounds which occur naturally in the earth's crust.
e.g. Bauxite is a mineral that contains aluminium.
Ore
A mineral from which a metal can be profitably extracted.
e.g. Bauxite is an ore of aluminium; cinnabar is an ore of mercury.
Gangue
The impurities such as soil and sand present in an ore.
e.g. During extraction, gangue is removed from the ore before metal extraction.
Roasting
The process of heating sulphide ores strongly in the presence of excess air to convert them into oxides.
e.g. 2ZnS + 3O₂ → 2ZnO + 2SO₂ (roasting of zinc sulphide).
Calcination
The process of heating carbonate ores strongly in limited air to convert them into oxides.
e.g. ZnCO₃ → ZnO + CO₂ (calcination of zinc carbonate).
Corrosion
The phenomenon where the surface of metals is attacked by substances in the environment, leading to deterioration.
e.g. Rusting of iron, tarnishing of silver, and greening of copper are examples of corrosion.
Alloy
A homogeneous mixture of two or more metals, or a metal and a non-metal.
e.g. Brass (copper and zinc), bronze (copper and tin), and stainless steel (iron, nickel, chromium) are alloys.
Galvanisation
A method of protecting steel and iron from rusting by coating them with a thin layer of zinc.
e.g. Iron sheets used for roofing are often galvanised.
Anodising
A process of forming a thick oxide layer of aluminium by making it the anode during electrolysis with dilute sulphuric acid.
e.g. Anodised aluminium articles have a thicker protective oxide layer that can be dyed for attractive finish.
Electrolytic refining
A method of refining impure metals using electrolysis, where the impure metal is made the anode and a pure metal strip is the cathode.
e.g. Copper is refined electrolytically using acidified copper sulphate solution as electrolyte.
Thermit reaction
A highly exothermic displacement reaction between iron(III) oxide and aluminium, used to join railway tracks or cracked machine parts.
e.g. Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + Heat.
Aqua regia
A freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio 3:1, capable of dissolving gold and platinum.
e.g. Aqua regia is used to dissolve gold in jewellery making or refining processes.
Formulas & Equations (26)
Metal + Oxygen → Metal oxide
Reads as: Metal plus oxygen gives metal oxide
Variables: Metal: any metallic element; Oxygen: O₂; Metal oxide: product containing metal and oxygen
Use when: Writing general reaction of metals with oxygen, especially for basic or amphoteric oxide formation
⚠ Students forget to balance the equation or incorrectly write the formula of the metal oxide (e.g., writing AlO instead of Al₂O₃)
2Cu + O₂ → 2CuO
Reads as: Two copper plus oxygen gives two copper(II) oxide
Variables: Cu: copper; O₂: oxygen; CuO: copper(II) oxide (black)
Use when: Describing the reaction of copper with oxygen on heating
⚠ Writing Cu₂O instead of CuO; copper forms CuO (black) not Cu₂O (red) in this reaction
4Al + 3O₂ → 2Al₂O₃
Reads as: Four aluminium plus three oxygen gives two aluminium oxide
Variables: Al: aluminium; O₂: oxygen; Al₂O₃: aluminium oxide
Use when: Describing the reaction of aluminium with oxygen
⚠ Forgetting to balance the equation or writing AlO instead of Al₂O₃
Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
Reads as: Aluminium oxide plus six hydrochloric acid gives two aluminium chloride plus three water
Variables: Al₂O₃: aluminium oxide; HCl: hydrochloric acid; AlCl₃: aluminium chloride; H₂O: water
Use when: Showing amphoteric nature of aluminium oxide reacting with an acid
⚠ Writing AlCl₂ instead of AlCl₃; aluminium has +3 oxidation state
Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
Reads as: Aluminium oxide plus two sodium hydroxide gives two sodium aluminate plus water
Variables: Al₂O₃: aluminium oxide; NaOH: sodium hydroxide; NaAlO₂: sodium aluminate; H₂O: water
Use when: Showing amphoteric nature of aluminium oxide reacting with a base
⚠ Writing Al(OH)₃ as product instead of NaAlO₂; students forget the specific product sodium aluminate
Na₂O(s) + H₂O(l) → 2NaOH(aq)
Reads as: Sodium oxide solid plus water liquid gives two sodium hydroxide aqueous
Variables: Na₂O: sodium oxide; H₂O: water; NaOH: sodium hydroxide (alkali)
Use when: Describing how some metal oxides dissolve in water to form alkalis
⚠ Forgetting to write state symbols or writing NaOH as solid instead of aqueous
K₂O(s) + H₂O(l) → 2KOH(aq)
Reads as: Potassium oxide solid plus water liquid gives two potassium hydroxide aqueous
Variables: K₂O: potassium oxide; H₂O: water; KOH: potassium hydroxide
Use when: Describing how potassium oxide forms an alkali with water
⚠ Confusing with sodium oxide reaction; both are similar but potassium is more reactive
Metal + Water → Metal oxide + Hydrogen
Reads as: Metal plus water gives metal oxide plus hydrogen
Variables: Metal: any reactive metal; Water: H₂O; Metal oxide: product; Hydrogen: H₂
Use when: Writing general reaction of metals with water or steam
⚠ Students often write metal hydroxide directly without showing the intermediate oxide step
2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g) + heat energy
Reads as: Two potassium solid plus two water liquid gives two potassium hydroxide aqueous plus hydrogen gas plus heat energy
Variables: K: potassium; H₂O: water; KOH: potassium hydroxide; H₂: hydrogen; heat energy: exothermic
Use when: Describing the violent reaction of potassium with cold water
⚠ Forgetting to write 'heat energy' or writing K₂O instead of KOH
2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g) + heat energy
Reads as: Two sodium solid plus two water liquid gives two sodium hydroxide aqueous plus hydrogen gas plus heat energy
Variables: Na: sodium; H₂O: water; NaOH: sodium hydroxide; H₂: hydrogen; heat energy: exothermic
Use when: Describing the violent reaction of sodium with cold water
⚠ Writing Na₂O instead of NaOH; sodium reacts with water to form hydroxide, not oxide
Ca(s) + 2H₂O(l) → Ca(OH)₂(aq) + H₂(g)
Reads as: Calcium solid plus two water liquid gives calcium hydroxide aqueous plus hydrogen gas
Variables: Ca: calcium; H₂O: water; Ca(OH)₂: calcium hydroxide; H₂: hydrogen
Use when: Describing the less violent reaction of calcium with cold water
⚠ Writing CaO instead of Ca(OH)₂; calcium forms hydroxide with water
2Al(s) + 3H₂O(g) → Al₂O₃(s) + 3H₂(g)
Reads as: Two aluminium solid plus three steam gives aluminium oxide solid plus three hydrogen gas
Variables: Al: aluminium; H₂O(g): steam; Al₂O₃: aluminium oxide; H₂: hydrogen
Use when: Describing the reaction of aluminium with steam
⚠ Writing Al(OH)₃ instead of Al₂O₃; aluminium reacts with steam to form oxide, not hydroxide
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)
Reads as: Three iron solid plus four steam gives iron(II,III) oxide solid plus four hydrogen gas
Variables: Fe: iron; H₂O(g): steam; Fe₃O₄: magnetic iron oxide; H₂: hydrogen
Use when: Describing the reaction of iron with steam
⚠ Writing Fe₂O₃ instead of Fe₃O₄; iron with steam forms Fe₃O₄ (magnetite), not Fe₂O₃
Metal + Dilute acid → Salt + Hydrogen
Reads as: Metal plus dilute acid gives salt plus hydrogen
Variables: Metal: reactive metal; Dilute acid: e.g., HCl, H₂SO₄; Salt: metal chloride or sulphate; Hydrogen: H₂
Use when: Writing general reaction of metals with dilute acids
⚠ Forgetting that nitric acid does not produce hydrogen; students apply this rule to all acids
Metal A + Salt solution of B → Salt solution of A + Metal B
Reads as: Metal A plus salt solution of B gives salt solution of A plus metal B
Variables: Metal A: more reactive metal; Salt solution of B: compound of less reactive metal; Salt solution of A: compound of A; Metal B: less reactive metal displaced
Use when: Describing displacement reactions between metals and salt solutions
⚠ Students think the reaction occurs even if A is less reactive than B; displacement only happens if A is more reactive
2HgS(s) + 3O₂(g) → 2HgO(s) + 2SO₂(g)
Reads as: Two mercury(II) sulphide solid plus three oxygen gas gives two mercury(II) oxide solid plus two sulphur dioxide gas
Variables: HgS: cinnabar (mercury ore); O₂: oxygen; HgO: mercuric oxide; SO₂: sulphur dioxide
Use when: Describing the first step in extracting mercury from its ore by heating in air
⚠ Writing Hg₂O instead of HgO; mercury forms HgO (mercuric oxide)
2HgO(s) → 2Hg(l) + O₂(g)
Reads as: Two mercury(II) oxide solid gives two mercury liquid plus oxygen gas
Variables: HgO: mercuric oxide; Hg: liquid mercury; O₂: oxygen
Use when: Describing the second step in extracting mercury by further heating of HgO
⚠ Forgetting that this is a decomposition reaction; students may write it as a reduction with carbon
2Cu₂S + 3O₂(g) → 2Cu₂O(s) + 2SO₂(g)
Reads as: Two copper(I) sulphide plus three oxygen gives two copper(I) oxide plus two sulphur dioxide
Variables: Cu₂S: copper(I) sulphide; O₂: oxygen; Cu₂O: copper(I) oxide; SO₂: sulphur dioxide
Use when: Describing the roasting of copper ore to form copper(I) oxide
⚠ Writing CuO instead of Cu₂O; the ore Cu₂S gives Cu₂O on roasting
2Cu₂O + Cu₂S → 6Cu + SO₂(g)
Reads as: Two copper(I) oxide plus copper(I) sulphide gives six copper plus sulphur dioxide
Variables: Cu₂O: copper(I) oxide; Cu₂S: copper(I) sulphide; Cu: copper metal; SO₂: sulphur dioxide
Use when: Describing the reduction step to obtain copper from its oxide and sulphide
⚠ Students think this is a simple displacement; it is a redox reaction between copper compounds
2ZnS(s) + 3O₂(g) → 2ZnO(s) + 2SO₂(g)
Reads as: Two zinc sulphide solid plus three oxygen gas gives two zinc oxide solid plus two sulphur dioxide gas
Variables: ZnS: zinc sulphide; O₂: oxygen; ZnO: zinc oxide; SO₂: sulphur dioxide
Use when: Describing roasting of zinc sulphide ore
⚠ Writing ZnSO₄ instead of ZnO; roasting produces oxide, not sulphate
ZnCO₃(s) → ZnO(s) + CO₂(g)
Reads as: Zinc carbonate solid gives zinc oxide solid plus carbon dioxide gas
Variables: ZnCO₃: zinc carbonate; ZnO: zinc oxide; CO₂: carbon dioxide
Use when: Describing calcination of zinc carbonate ore
⚠ Writing Zn + CO₂ instead of ZnO + CO₂; calcination gives oxide, not metal
ZnO(s) + C(s) → Zn(s) + CO(g)
Reads as: Zinc oxide solid plus carbon solid gives zinc solid plus carbon monoxide gas
Variables: ZnO: zinc oxide; C: carbon (coke); Zn: zinc metal; CO: carbon monoxide
Use when: Describing reduction of zinc oxide using carbon
⚠ Writing CO₂ instead of CO; reduction with carbon typically produces CO, not CO₂
3MnO₂(s) + 4Al(s) → 3Mn(l) + 2Al₂O₃(s) + Heat
Reads as: Three manganese dioxide solid plus four aluminium solid gives three manganese liquid plus two aluminium oxide solid plus heat
Variables: MnO₂: manganese dioxide; Al: aluminium; Mn: manganese; Al₂O₃: aluminium oxide; Heat: exothermic
Use when: Describing displacement reaction using aluminium as reducing agent for manganese dioxide
⚠ Writing MnO instead of Mn; the product is molten manganese metal, not its oxide
Fe₂O₃(s) + 2Al(s) → 2Fe(l) + Al₂O₃(s) + Heat
Reads as: Iron(III) oxide solid plus two aluminium solid gives two iron liquid plus aluminium oxide solid plus heat
Variables: Fe₂O₃: iron(III) oxide; Al: aluminium; Fe: molten iron; Al₂O₃: aluminium oxide; Heat: exothermic
Use when: Describing the thermit reaction used for joining railway tracks
⚠ Writing FeO instead of Fe₂O₃; the correct ore is Fe₂O₃ (haematite)
At cathode: Na⁺ + e⁻ → Na
Reads as: At cathode, sodium ion plus one electron gives sodium metal
Variables: Na⁺: sodium ion; e⁻: electron; Na: sodium metal
Use when: Describing electrolytic reduction of molten sodium chloride to obtain sodium
⚠ Writing Na⁺ + 2e⁻ → Na; sodium requires only one electron to become neutral
At anode: 2Cl⁻ → Cl₂ + 2e⁻
Reads as: At anode, two chloride ions give chlorine gas plus two electrons
Variables: Cl⁻: chloride ion; Cl₂: chlorine gas; e⁻: electrons
Use when: Describing the anode reaction during electrolysis of molten sodium chloride
⚠ Writing Cl⁻ → Cl + e⁻; chlorine is diatomic (Cl₂), not monatomic
How It Works
Formation of ionic compounds (Electrovalent bonding)
  1. Step 1: A metal atom loses one or more electrons from its valence shell to achieve a stable noble gas configuration, forming a positively charged cation.
  2. Step 2: A non-metal atom gains those electrons to complete its octet, forming a negatively charged anion.
  3. Step 3: The oppositely charged ions are held together by strong electrostatic forces of attraction, forming an ionic compound.
  4. Step 4: The compound exists as an aggregate of ions, not as discrete molecules.
💡 Students often think ionic compounds exist as molecules; they are actually giant ionic lattices. Also, the transfer of electrons is from metal to non-metal only.
Extraction of metals based on reactivity series
  1. Step 1: Ores are mined from the earth's crust and the gangue (impurities) is removed through enrichment processes.
  2. Step 2: For metals low in the activity series (e.g., Hg, Cu), the ore is heated in air to directly obtain the metal or its oxide which then decomposes.
  3. Step 3: For metals in the middle of the series (e.g., Zn, Fe, Pb), sulphide ores are roasted and carbonate ores are calcined to convert them into oxides.
  4. Step 4: The metal oxides are then reduced using carbon (coke) or by displacement reactions with more reactive metals like aluminium.
  5. Step 5: For metals high in the series (e.g., Na, K, Ca, Al), electrolytic reduction of their molten chlorides or oxides is used because carbon cannot reduce them.
💡 Students often confuse roasting (excess air) with calcination (limited air). Also, carbon can only reduce metals below aluminium in the reactivity series.
Electrolytic refining of metals
  1. Step 1: The impure metal is made the anode, and a thin strip of pure metal is made the cathode.
  2. Step 2: A solution of the metal salt (e.g., acidified copper sulphate for copper) is used as the electrolyte.
  3. Step 3: On passing electric current, pure metal from the anode dissolves into the electrolyte.
  4. Step 4: An equivalent amount of pure metal from the electrolyte is deposited on the cathode.
  5. Step 5: Soluble impurities go into the solution, while insoluble impurities settle at the bottom as anode mud.
💡 Students often think the impure metal is the cathode; it is always the anode. Also, the electrolyte must be a salt of the same metal.
Rusting of iron (Corrosion of iron)
  1. Step 1: Iron is exposed to both air (oxygen) and water (moisture) simultaneously.
  2. Step 2: A chemical reaction occurs forming hydrated iron(III) oxide, commonly known as rust.
  3. Step 3: Rust is a brown, flaky substance that weakens the iron over time.
  4. Step 4: Rusting can be prevented by painting, oiling, greasing, galvanising, chrome plating, anodising, or alloying.
💡 Students often think rusting requires only water or only air; both are essential. The experiment with test tubes A, B, C proves this.
Anodising of aluminium
  1. Step 1: A clean aluminium article is made the anode in an electrolytic cell containing dilute sulphuric acid.
  2. Step 2: During electrolysis, oxygen gas is evolved at the anode.
  3. Step 3: The oxygen reacts with aluminium to form a thicker protective oxide layer on the surface.
  4. Step 4: This oxide layer can be dyed easily to give an attractive finish.
💡 Students confuse anodising with electroplating; anodising forms an oxide layer, not a metal coating.
Exam Traps — Don't Make These Mistakes
⚠ Writing 'All metals are hard'
✗ All metals are hard solids at room temperature.
→ Mercury is a liquid at room temperature, and alkali metals like sodium and potassium are so soft they can be cut with a knife.
✓ All metals except mercury are solids at room temperature, and hardness varies; alkali metals are soft.
⚠ Confusing roasting and calcination
✗ Roasting and calcination are the same process.
→ Roasting is done for sulphide ores in excess air, while calcination is done for carbonate ores in limited air. They produce different products (SO₂ vs CO₂).
✓ Roasting: heating sulphide ores in excess air to form oxide and SO₂. Calcination: heating carbonate ores in limited air to form oxide and CO₂.
⚠ Assuming all metals react with water
✗ All metals react with water to produce hydrogen gas.
→ Only highly reactive metals (K, Na, Ca) react with cold water; Mg reacts with hot water; Al, Fe, Zn react only with steam; Cu, Ag, Au do not react with water at all.
✓ Metals like K, Na, Ca react with cold water; Mg reacts with hot water; Al, Fe, Zn react with steam; Cu, Ag, Au do not react with water.
⚠ Thinking nitric acid always produces hydrogen with metals
✗ Metals react with nitric acid to produce hydrogen gas.
→ Nitric acid is a strong oxidising agent; it oxidises the hydrogen produced to water and itself gets reduced to nitrogen oxides (N₂O, NO, NO₂). Only Mg and Mn with very dilute HNO₃ evolve H₂.
✓ Hydrogen gas is not evolved when a metal reacts with nitric acid because HNO₃ is a strong oxidising agent. Exception: Mg and Mn with very dilute HNO₃.
⚠ Confusing anode and cathode in electrolytic refining
✗ In electrolytic refining, the impure metal is made the cathode and pure metal is made the anode.
→ The impure metal is always the anode because it dissolves into the electrolyte, and pure metal deposits on the cathode.
✓ In electrolytic refining, the impure metal is the anode and a thin strip of pure metal is the cathode.
⚠ Saying 'All metal oxides are basic'
✗ All metal oxides are basic in nature.
→ Some metal oxides like Al₂O₃ and ZnO are amphoteric (react with both acids and bases). Also, some metal oxides like Na₂O and K₂O dissolve in water to form alkalis.
✓ Most metal oxides are basic, but some like Al₂O₃ and ZnO are amphoteric. Na₂O and K₂O dissolve in water to form alkalis.
Compare & Contrast
Physical properties (lustre, malleability, ductility, conductivity, sonority)
Metals
Non-metals
Metals are lustrous, malleable, ductile, good conductors of heat and electricity, and sonorous; non-metals are generally non-lustrous (except iodine), brittle, non-ductile, poor conductors (except graphite), and non-sonorous.
Process of converting ores into oxides
Roasting
Calcination
Roasting is heating sulphide ores in excess air to produce oxide and SO₂; calcination is heating carbonate ores in limited air to produce oxide and CO₂.
Conduction of electricity
Ionic compounds in solid state
Ionic compounds in molten state
In solid state, ions are held in rigid positions and cannot move, so they do not conduct electricity; in molten state, electrostatic forces are overcome by heat, ions move freely, and they conduct electricity.
Exam Focus
Marks pattern: Typically 2-3 MCQs (1 mark each), 1-2 Very Short Answer (1 mark), 1 Short Answer (3 marks), and 1 Long Answer (5 marks). Total approximately 10-12 marks.
Most asked: Reactivity series and its applications (displacement reactions, reaction with water/acid) · Properties of ionic compounds (high melting point, conductivity in molten state) · Extraction of metals (roasting, calcination, reduction, electrolytic refining) · Corrosion and its prevention (rusting conditions, galvanisation, alloying) · Amphoteric oxides (definition and examples with equations)
Don't skip: Long answer question on extraction of metals based on reactivity series (5 marks) — often includes writing equations for roasting, calcination, and reduction.; Short answer on displacement reactions and reactivity series (3 marks) — predicting whether a reaction occurs and writing balanced equations.; Question on properties of ionic compounds (3 marks) — explaining high melting point and conductivity in molten state.
One-Line Revision (read aloud before the exam)
  1. Metals are lustrous, malleable, ductile, sonorous, and good conductors of heat and electricity, while non-metals are generally the opposite except for graphite (conducts electricity) and iodine (lustrous).
  2. Mercury is the only metal that is liquid at room temperature; gallium and caesium have very low melting points.
  3. Gold and silver are the most malleable metals; gold is the most ductile metal.
  4. Metal oxides are generally basic, but aluminium oxide and zinc oxide are amphoteric (react with both acids and bases).
  5. Sodium and potassium react violently with cold water and are stored under kerosene oil to prevent accidental fires.
  6. Calcium reacts less violently with cold water and floats due to hydrogen bubbles sticking to its surface.
  7. Magnesium reacts with hot water; aluminium, iron, and zinc react only with steam.
  8. Copper, silver, and gold do not react with water at all.
  9. Hydrogen gas is not evolved when metals react with nitric acid because it is a strong oxidising agent; exception: Mg and Mn with very dilute HNO₃.
  10. A more reactive metal displaces a less reactive metal from its salt solution in a displacement reaction.
  11. The reactivity series from most to least reactive: K, Na, Ca, Mg, Al, Zn, Fe, Pb, [H], Cu, Hg, Ag, Au.
  12. Ionic compounds have high melting and boiling points due to strong electrostatic forces between ions.
  13. Ionic compounds conduct electricity in molten or aqueous state but not in solid state.
  14. Ores of metals low in reactivity series (Hg, Cu) can be reduced by heating alone.
  15. Sulphide ores are converted to oxides by roasting (excess air); carbonate ores by calcination (limited air).
  16. Metals in the middle of the series (Zn, Fe, Pb) are reduced using carbon (coke) or by displacement with more reactive metals.
  17. Metals high in the series (K, Na, Ca, Al) are obtained by electrolytic reduction of their molten compounds.
  18. The thermit reaction (Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + Heat) is used to join railway tracks.
  19. Electrolytic refining uses impure metal as anode, pure metal as cathode, and a salt solution as electrolyte.
  20. Rusting of iron requires both air (oxygen) and water; it can be prevented by painting, galvanising, or alloying.
  21. Galvanisation is coating iron or steel with a thin layer of zinc to prevent rusting.
  22. An alloy is a homogeneous mixture of two or more metals or a metal and a non-metal; alloys have lower conductivity and melting point than pure metals.
  23. Brass (Cu+Zn), bronze (Cu+Sn), and stainless steel (Fe+Ni+Cr) are common alloys.
  24. Aqua regia (3:1 mixture of conc. HCl and conc. HNO₃) can dissolve gold and platinum.

MCQs — 10 Questions with Answers

Q1. A student observes that when a copper wire is heated at one end while holding the other end with bare hands, the hand feels hot after a few seconds. Which property of metals does this observation demonstrate?

  • A. Copper is a good conductor of heat ✓
  • B. Copper has high melting point
  • C. Copper is malleable
  • D. Copper is ductile

Answer: A — The heat traveling from the heated end to the unheated end demonstrates thermal conductivity; students often confuse this with melting point or mechanical properties like malleability.

Q2. In a school laboratory, a student needs to make a long thin wire from a metal sample. Which property of metals should the teacher recommend to use?

  • A. Ductility ✓
  • B. Malleability
  • C. Sonority
  • D. Lustre

Answer: A — Ductility is the ability to be drawn into wires; malleability is for beating into sheets, not stretching into wires.

Q3. Assertion (A): Mercury is a metal that exists as a liquid at room temperature. Reason (R): All metals have high melting points. Choose the correct option:

  • A. Both A and R are true and R is the correct explanation of A
  • B. Both A and R are true but R is not the correct explanation of A
  • C. A is true but R is false ✓
  • D. A is false but R is true

Answer: C — Mercury is indeed a liquid metal at room temperature, but this contradicts the reason that all metals have high melting points; the assertion is true but the reason is false.

Q4. A household electrical wire has copper conductor wrapped with plastic coating. Based on properties of metals and non-metals, explain why copper is used for the conductor part.

  • A. Copper is a good conductor of electricity and the plastic coating (non-metal) insulates it ✓
  • B. Copper is lustrous and plastic makes it invisible
  • C. Copper is hard and plastic makes it flexible
  • D. Copper is malleable and plastic prevents corrosion

Answer: A — Copper conducts electricity while the non-metal plastic insulator prevents electric shock; students often confuse this with aesthetic or mechanical properties.

Q5. In Activity 3.7, when sulphur powder is burned and the fumes are collected in water, the resulting solution turns blue litmus paper red. What does this indicate about non-metals?

  • A. Non-metals form acidic oxides when burned ✓
  • B. Non-metals form basic oxides when burned
  • C. Non-metals do not burn in air
  • D. Non-metals are always acidic

Answer: A — Burning sulphur produces SO₂ which forms acidic H₂SO₃ in water; students may confuse this with metals which typically form basic oxides.

Q6. Assertion (A): Diamond and graphite have different physical properties despite both being forms of carbon. Reason (R): Physical properties depend on the arrangement of atoms in the substance. Choose the correct option:

  • A. Both A and R are true and R is the correct explanation of A ✓
  • B. Both A and R are true but R is not the correct explanation of A
  • C. A is true but R is false
  • D. A is false but R is true

Answer: A — Different atomic arrangements create allotropes with distinct properties; the reason directly explains why diamond (hard, insulator) and graphite (soft, conductor) differ.

Q7. A student strikes a metal with a hammer and observes that the metal bends rather than breaks. Another student burns the same metal and observes that the oxide formed is basic. Which two properties are being demonstrated here?

  • A. Malleability and basic oxide formation ✓
  • B. Ductility and acidic oxide formation
  • C. Sonority and basic oxide formation
  • D. Hardness and neutral oxide formation

Answer: A — Bending without breaking shows malleability (physical property); basic oxide formation is a characteristic chemical property of metals.

Q8. Assertion (A): Iodine is a non-metal with a lustrous surface. Reason (R): All substances with metallic lustre are metals. Choose the correct option:

  • A. Both A and R are true and R is the correct explanation of A
  • B. Both A and R are true but R is not the correct explanation of A
  • C. A is true but R is false ✓
  • D. A is false but R is true

Answer: C — Iodine is indeed a non-metal with lustre, contradicting the reason that lustre indicates a metal; physical properties alone cannot classify elements.

Q9. In an experiment, a student tests the electrical conductivity of coal (carbon) and copper using the circuit in Fig. 3.2. The bulb glows only when copper is placed between terminals A and B. What can be concluded?

  • A. Metals are generally good conductors of electricity while non-metals are not ✓
  • B. Carbon is a better conductor than copper
  • C. Non-metals never conduct electricity
  • D. Copper is a non-metal because it conducts electricity

Answer: A — Copper's conductivity confirms metals conduct electricity while carbon (non-metal) does not; students may incorrectly assume all non-metals are non-conductors, but graphite is an exception.

Q10. A student attempts to cut sodium metal with a knife and finds it very soft and cuts easily. Why is sodium metal not used for making cooking vessels despite being a metal?

  • A. Sodium is too soft and has a low melting point unsuitable for heating ✓
  • B. Sodium is not a conductor of electricity
  • C. Sodium is not malleable like other metals
  • D. Sodium does not have metallic lustre

Answer: A — Sodium's softness and low melting point make it unsuitable for cookware; students may focus on electrical or optical properties rather than mechanical strength.

Flashcards

What is metallic lustre?

The shining or lustrous appearance of pure metals due to their atomic structure.

Define malleability.

The property of metals that allows them to be beaten into thin sheets without breaking.

What is ductility in metals?

The ability of metals to be drawn into long, thin wires without breaking.

Why are copper and aluminium used for cooking vessels?

Because they are good conductors of heat and have high melting points.

Name the most ductile metal.

Gold is the most ductile metal; 1 gram can produce a wire of about 2 km length.

What do we mean by sonority in metals?

The property of metals to produce a sound when struck against a hard surface.

Why are electric wires coated with PVC or rubber?

PVC and rubber are non-conductors of electricity and insulate the wire to prevent electric shock.

What are allotropes of carbon?

Different forms of carbon element such as diamond, graphite, and coal with different properties.

Which non-metal is lustrous?

Iodine is a non-metal that has a lustrous or shining appearance.

What oxides do metals form when burnt in air?

Metals form basic (alkaline) oxides when burnt in air, which dissolve in water to give basic solutions.

Important Board Questions

Give one example each of a metal which (i) is liquid at room temperature, (ii) can be easily cut with a knife, (iii) is the best conductor of heat. [2 marks]

Recall specific metal examples: liquid metal at room temperature = Mercury; soft metal that can be cut = Sodium (or potassium, lithium); best heat conductor = Silver (or copper).

Explain why iodine is classified as a non-metal even though it has a lustrous appearance. What does this tell us about classifying elements based on physical properties alone? [3 marks]

Iodine's lustre is an exception to physical property rules; classification must rely on chemical properties (iodine forms acidic oxides). Physical properties have too many exceptions (diamond hardness, graphite conductivity, mercury liquid state, alkali metals softness).

When magnesium ribbon is burnt, it forms magnesium oxide. When sulphur powder is burnt, it forms sulphur dioxide. Explain why magnesium oxide is basic while sulphur dioxide is acidic. What does this difference reveal about the chemical nature of metals versus non-metals? Support your answer with the behaviour of their oxides in water. [5 marks]

Metals lose electrons and form basic oxides (MgO + H₂O → Mg(OH)₂, basic); non-metals gain electrons and form acidic oxides (SO₂ + H₂O → H₂SO₃, acidic). This reflects fundamental difference in electron behaviour: metals are electron donors, non-metals are electron acceptors. Chemical classification is more reliable than physical properties.

Assertion-Reason Questions for Metals and Non-metals

Q1. Assertion (A):

Mercury is a metal even though it is liquid at room temperature.

Reason (R):

Mercury exhibits metallic properties like electrical conductivity and metallic lustre, even though it does not follow the general physical property of being solid at room temperature.

Answer: A — Both A and R are true, and R is the correct explanation of A — Both assertion and reason are true, and the reason correctly explains why mercury is classified as a metal despite being a liquid. The classification is based on chemical properties and behavior, not just the physical state at room temperature. This demonstrates that exceptions exist and we must use multiple criteria for classification.

Q2. Assertion (A):

Iodine is a non-metal with a lustrous appearance.

Reason (R):

Iodine exhibits the property of metallic lustre because it is not a true non-metal but actually a metalloid.

Answer: C — A is true but R is false — The assertion is true—iodine is indeed a lustrous non-metal. However, the reason is false. Iodine is a true non-metal, not a metalloid. Iodine's lustrous appearance is an exception to the general property that non-metals lack lustre. Its metalloid status is not the reason for its lustrous nature; rather, it is simply an exceptional non-metal with this property.

Q3. Assertion (A):

Metals can be beaten into thin sheets because they are malleable.

Reason (R):

The atomic arrangement in metals allows them to slide past each other without breaking the metallic bonds, enabling them to deform into new shapes.

Answer: A — Both A and R are true, and R is the correct explanation of A — Both the assertion and reason are correct, and the reason accurately explains why metals are malleable. The metallic bonding in metals is non-directional, allowing atoms to rearrange and slide past each other when force is applied. This unique bonding structure is the fundamental cause of malleability, explaining why metals can be hammered into sheets.

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Case-Based Questions (CBQ) for Metals and Non-metals

Case Study:

A student conducted Activity 3.5 to test the conductivity of heat in metals. She clamped a copper wire vertically on a stand and attached a small wax dot at different distances from the clamp. She heated the wire near the clamp with a bunsen burner and recorded the time taken for the wax at different distances to melt and fall off. The results showed that wax at 5 cm distance melted in 30 seconds, at 10 cm in 60 seconds, at 15 cm in 95 seconds, and at 20 cm in 135 seconds. When she repeated the experiment with an iron wire, the times were approximately double those of copper.

Q1. Based on the experiment, which metal is a better conductor of heat?

  • A. Iron is a better conductor because the wax melted faster
  • B. Copper is a better conductor because the wax melted faster ✓
  • C. Both metals conduct heat equally
  • D. It depends on the thickness of the wire

Answer: B

Q2. Why did the wax melt and the pin fall off instead of the wire melting?

  • A. The melting point of wax is lower than the melting point of the metal ✓
  • B. The wax was exposed to higher temperature
  • C. Wax is a better conductor of heat than metal
  • D. The metal wire expanded and pushed the pin off

Answer: A

Q3. What does the linear increase in time with distance suggest about heat conduction in the metal?

  • A. Heat is conducted at a constant rate along the wire
  • B. Heat conduction decreases exponentially with distance
  • C. Heat is conducted faster near the source and slower at greater distances ✓
  • D. The wire conducts heat only at specific points

Answer: C

Q4. Why would copper be preferred over iron for making cooking vessel bases?

  • A. Copper is cheaper than iron
  • B. Copper is more durable than iron
  • C. Copper conducts heat more efficiently, distributing heat evenly for better cooking ✓
  • D. Copper has a lower melting point than iron

Answer: C

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Previous Year Questions (PYQ) for Metals and Non-metals

Real CBSE board exam questions from past papers — free to attempt.

CBSE 2026 · Set 31/4/1 · 1 mark

Which one of the following metals does not react with cold water?

  • Sodium
  • Potassium
  • Calcium
  • Magnesium

CBSE 2026 · Set 31/4/1 · 1 mark

Alloys are homogeneous mixture of metal with a metal or non-metal. Which among the following alloys contain non-metal as one of its constituents?

  • Brass
  • Bronze
  • Amalgam
  • Steel

CBSE 2026 · Set 31/4/1 · 3 marks

(A) (i) Which method will be used to convert each of them to their respective metal oxides? (a) Carbonate ore (b) Sulphide ore (ii) Write a chemical reaction to illustrate the use of aluminium for joining cracked railway tracks. (iii) During extraction of metals, electrolytic refining is used to obtain pure metals. Which material will be used as anode and cathode for the refining of copper metal by this process?

CBSE 2026 · Set 31/4/2 · 1 mark

Which one of the following metals neither reacts with cold water nor reacts with hot water but reacts with steam?

  • Sodium
  • Calcium
  • Iron
  • Magnesium

CBSE 2026 · Set 31/4/3 · 1 mark

Solder is an alloy of

  • copper and zinc
  • lead and zinc
  • lead and tin
  • copper and tin

CBSE 2026 · Set 31/4/3 · 3 marks

(i) Which method will be used to convert each of them to their respective metal oxides? (a) Carbonate ore (b) Sulphide ore (ii) Write a chemical reaction to illustrate the use of aluminium for joining cracked railway tracks. (iii) During extraction of metals, electrolytic refining is used to obtain pure metals. Which material will be used as anode and cathode for the refining of copper metal by this process?

CBSE 2026 · Set 31/5/1 · 1 mark

Which gas is evolved when magnesium metal reacts with very dilute HNO3?

  • Oxygen
  • Nitrogen
  • Hydrogen
  • Nitrogen Dioxide

CBSE 2026 · Set 31/5/1 · 5 marks

(A) (i) Give reasons for the following: (I) Ionic compound have generally high melting points and boiling points. (II) Solder, an alloy of lead and tin, is used for welding electrical wires. (III) Carbon cannot reduce the oxides of Na or Mg. (ii) The reaction of compound 'X' with aluminium is used to join railway tracks: (I) Identify the compound 'X'. (II) Name the reaction. (III) Write the balanced chemical equation of the reaction of compound 'X' with aluminium.

CBSE 2026 · Set 31/5/1 · 1 mark

Which of the following is an amphoteric oxide?

  • Na₂O
  • K₂O
  • CO₂
  • Al₂O₃

CBSE 2026 · Set 31/5/2 · 1 mark

On reaction with dilute HCl, which of the following pair of metals will evolve hydrogen gas ?

  • copper and zinc
  • copper and iron
  • silver and magnesium
  • magnesium and aluminium

CBSE 2026 · Set 31/5/2 · 5 marks

(A) (i) Give reasons for the following : (I) Ionic compound have generally high melting points and boiling points. (II) Solder, an alloy of lead and tin, is used for welding electrical wires. (III) Carbon cannot reduce the oxides of Na or Mg. (ii) The reaction of compound 'X' with aluminium is used to join railway tracks : (I) Identify the compound 'X'. (II) Name the reaction. (III) Write the balanced chemical equation of the reaction of compound 'X' with aluminium.

CBSE 2026 · Set 31/5/3 · 1 mark

Galvanization is a process of coating iron articles with a thin layer of zinc to prevent iron from rusting. The iron is protected even if the zinc coating is scratched and iron is exposed. Which of the following is/are true about how zinc prevents the rusting of iron? (P) A galvanised iron article does not undergo oxidation. (Q) The zinc coating prevents contact of iron with air. (R) Zinc provides continuous protection to iron from rusting.

  • Only (P)
  • Only (Q)
  • (Q) and (R)
  • (P) and (Q)

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Class 10 Science Formula Sheet

Every formula and chemical equation from the 10 chapters on one page, checked against the NCERT textbook and the CBSE 2026-27 syllabus. Free PDF download.

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Class 10 Science Previous Year Questions, Chapter-wise

All 875 CBSE board questions from 2022–2026, sorted by chapter and question type. Free PDF download.

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