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Metals and Non-metals – Class 10 Science Chapter 3 Notes & NCERT PDF

Class 10ScienceChapter 3NCERT book: Science - Class 10

Notes and a simple summary of Chapter 3 of the NCERT Class 10 Science book, with the official chapter PDF, flashcards, an MCQ quiz and an AI tutor for your doubts.

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Chapter 3: Metals and Non-metals

Introduction

In Class IX you met about 118 elements, of which over 90 are metals, some are non-metals and a few are metalloids. This chapter compares physical and chemical properties of metals and non-metals, explains how metals and non-metals form ionic compounds, describes how metals are extracted and refined from their ores, and ends with corrosion and its prevention by alloying and other methods.

Key Concepts

1. Physical properties

Metals (Activities 3.1–3.6):

  • Lustre – shiny surface (metallic lustre).
  • Generally hard — but alkali metals sodium and potassium are soft and can be cut with a knife.
  • Malleable (beaten into sheets) — gold and silver are the most malleable.
  • Ductile (drawn into wires) — gold is the most ductile; 1 g of gold can be drawn into a wire about 2 km long.
  • Good conductors of heat — silver and copper are the best; lead and mercury are poor.
  • Good conductors of electricity; sonorous (make a ringing sound).
  • High melting points, except gallium and caesium, which melt even on your palm. Mercury is liquid at room temperature.

    • Non-metals – carbon, sulphur, iodine, oxygen, hydrogen etc. are solids or gases; bromine is a liquid. Generally not lustrous, brittle, poor conductors.

    Exceptions: iodine is lustrous; diamond (carbon) is the hardest natural substance with a very high melting point; graphite (carbon) conducts electricity.

    2. Chemical properties of metals

  • With oxygen → metal oxide (basic): 2Cu + O₂ → 2CuO (black); 4Al + 3O₂ → 2Al₂O₃.
  • Amphoteric oxides react with both acids and bases: Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O and Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O. ZnO is also amphoteric.
  • Soluble metal oxides form alkalis: Na₂O, K₂O.
  • Reactivity with oxygen: K and Na react so vigorously that they are kept under kerosene oil. Mg, Al, Zn, Pb form a protective oxide layer. Iron burns only as filings; copper forms black oxide; silver and gold do not react with oxygen even at high temperature.
  • Anodising: thickening the protective oxide layer on aluminium by electrolysis.
  • With water: Na and K react violently with cold water (hydrogen catches fire); calcium reacts less violently and floats (bubbles of H₂ stick to it); magnesium reacts with hot water and floats; Al, Fe and Zn react only with steam; Pb, Cu, Ag and Au do not react.
  • With dilute acids → salt + hydrogen, but HNO₃ is a strong oxidising agent, so hydrogen is not evolved except with Mg and Mn and very dilute acid. Reactivity: Mg > Al > Zn > Fe; copper does not react.
  • Aqua regia: freshly prepared 3 : 1 mixture of concentrated HCl and concentrated HNO₃ — dissolves gold and platinum.
  • Displacement: a more reactive metal displaces a less reactive one from its salt solution (Fe + CuSO₄ → FeSO₄ + Cu).
  • Reactivity series (most to least): K, Na, Ca, Mg, Al, Zn, Fe, Pb, [H], Cu, Hg, Ag, Au.

    • 3. How metals and non-metals react — ionic bonds

  • Noble gases have a complete outer shell and are stable. Other atoms lose or gain electrons to attain this octet.
  • Sodium (2, 8, 1) loses 1 electron → Na⁺; chlorine (2, 8, 7) gains 1 → Cl⁻. The oppositely charged ions attract to form NaCl.
  • Magnesium (2, 8, 2) loses 2 electrons → Mg²⁺; with two Cl⁻ gives MgCl₂.
  • Compounds formed by transfer of electrons are ionic (electrovalent) compounds.
  • Properties of ionic compounds: hard solids (strong attraction), somewhat brittle; high melting and boiling points; soluble in water, insoluble in kerosene and petrol; conduct electricity in molten state or in solution (ions move) but not as solids.

    • 4. Occurrence and extraction of metals

  • Earth's crust is the main source; sea water has soluble salts (NaCl, MgCl₂).
  • Minerals are naturally occurring elements/compounds; minerals from which metals can be profitably extracted are ores. Impurities (soil, sand) are called gangue.
  • Steps: enrichment of ore (remove gangue) → obtaining metal → refining.
  • Low-reactivity metals (e.g. mercury, copper): heating alone. Cinnabar: 2HgS + 3O₂ → 2HgO + 2SO₂; 2HgO → 2Hg + O₂. Cu₂S + O₂ → 2Cu + SO₂ (after partial roasting).
  • Middle-reactivity metals (Fe, Zn, Pb, Cu): ores are often sulphides or carbonates, first converted to oxides:

    • - Roasting – heating sulphide ore strongly in excess air: 2ZnS + 3O₂ → 2ZnO + 2SO₂.

    - Calcination – heating carbonate ore strongly in limited air: ZnCO₃ → ZnO + CO₂.

    - Oxide reduced by carbon: ZnO + C → Zn + CO.

    - Highly reactive metals like Al can also reduce: 3MnO₂ + 4Al → 3Mn + 2Al₂O₃. The thermit reaction Fe₂O₃ + 2Al → 2Fe + Al₂O₃ produces molten iron used to join railway tracks and cracked machine parts.

  • Highly reactive metals (Na, Mg, Ca, Al) cannot be reduced by carbon; they are obtained by electrolytic reduction of their molten chlorides — metal deposits at the cathode, chlorine at the anode.
  • Electrolytic refining (copper, zinc, tin, nickel, silver, gold): impure metal = anode, thin strip of pure metal = cathode, salt solution of the metal = electrolyte; pure metal deposits on the cathode, insoluble impurities settle as anode mud.

    • 5. Corrosion and its prevention

  • Silver turns black (silver sulphide, with sulphur in air); copper gains a green coat of basic copper carbonate; iron gets a brown flaky rust in moist air.
  • Activity 3.14 (three test tubes): nails rust only when both air and water are present — not in boiled water with oil on top (no air) or with anhydrous calcium chloride (no moisture).
  • Prevention: painting, oiling, greasing, galvanising (coating iron/steel with zinc — protected even if the coat is broken), chrome plating, anodising, and making alloys.
  • Alloy: a homogeneous mixture of two or more metals, or a metal and a non-metal. Pure iron is soft; with a little carbon (about 0.05%) it becomes hard and strong. Stainless steel = iron + nickel + chromium (does not rust). If one metal is mercury, the alloy is an amalgam. Brass = copper + zinc; bronze = copper + tin; solder = lead + tin (low melting point, for welding electric wires). Alloys have lower electrical conductivity and lower melting points than pure metals. Pure gold is 24 carat; ornaments use 22 carat gold (22 parts gold, 2 parts copper or silver) because pure gold is too soft.

    • Important Reactions (balanced)

  • 2Na + 2H₂O → 2NaOH + H₂ (+ heat)
  • Ca + 2H₂O → Ca(OH)₂ + H₂
  • 2Al + 3H₂O → Al₂O₃ + 3H₂ (steam); 3Fe + 4H₂O → Fe₃O₄ + 4H₂ (steam)
  • Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O; Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
  • 2ZnS + 3O₂ → 2ZnO + 2SO₂ (roasting); ZnCO₃ → ZnO + CO₂ (calcination)
  • ZnO + C → Zn + CO
  • Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat (thermit)
  • 2HgS + 3O₂ → 2HgO + 2SO₂; 2HgO → 2Hg + O₂

    • Activities in the Chapter

  • 3.1–3.6 – Examine lustre, hardness (cut sodium), malleability (hammer), ductility, heat conduction (wax on a wire), electrical conduction (circuit), sonority.
  • 3.7–3.8 – Compare non-metals; burn sulphur/magnesium and test the oxides with litmus: magnesium oxide is basic, sulphur oxide is acidic.
  • 3.9 – Heat metals in a flame; compare how they burn.
  • 3.10 – Metals with cold water, hot water and steam.
  • 3.11 – Metals with dilute HCl: rate of bubbling Mg > Al > Zn > Fe.
  • 3.12 – Put copper wire in iron sulphate and iron nail in copper sulphate: only iron displaces copper.
  • 3.13 – Properties of ionic compounds (heating, solubility, conduction).
  • 3.14 – Rusting of iron nails under three conditions.

    • Board Exam Focus

  • Exceptions to properties (Na/K soft, Hg liquid, Ga/Cs low m.p., iodine lustrous, graphite conducts, diamond hard).
  • Reactions of metals with water, acids and salt solutions; the reactivity series order.
  • Electron-dot formation of NaCl and MgCl₂; why ionic compounds conduct only when molten or dissolved.
  • Roasting vs calcination with equations; thermit reaction; electrolytic refining diagram.
  • Conditions for rusting and methods of prevention; composition of brass, bronze, solder, stainless steel.

    • Key Terms

  • Malleability (आघातवर्ध्यता)
  • Ductility (तन्यता)
  • Sonorous (ध्वानिक)
  • Amphoteric oxide (उभयधर्मी ऑक्साइड)
  • Reactivity series (सक्रियता श्रेणी)
  • Ionic compound (आयनिक यौगिक)
  • Ore (अयस्क)
  • Gangue (गैंग / आधात्री)
  • Roasting (भर्जन)
  • Calcination (निस्तापन)
  • Thermit reaction (थर्मिट अभिक्रिया)
  • Electrolytic refining (विद्युत अपघटनी परिष्करण)
  • Corrosion (संक्षारण)
  • Galvanisation (यशदलेपन)
  • Alloy (मिश्रातु)

    • Common Mistakes

  • Saying "all metals are solid and hard" — mercury is liquid, sodium is soft.
  • Expecting hydrogen from every metal + HNO₃ reaction — nitric acid oxidises the hydrogen (except with Mg and Mn in very dilute acid).
  • Confusing roasting (excess air, sulphide ores) with calcination (limited air, carbonate ores).
  • Writing that ionic solids conduct electricity — only molten or dissolved ionic compounds conduct.
  • Assuming painting a galvanised article is needed for protection — zinc protects iron even if the zinc coat is broken.

    • 💡 Key Learning Points

    • ✓Metals are lustrous, malleable, ductile, sonorous and good conductors, with notable exceptions (Na, K, Hg, Ga, Cs); non-metals have opposite properties with exceptions like iodine, graphite and diamond.
    • ✓Metals react with oxygen, water, acids and salt solutions according to the reactivity series K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au.
    • ✓Metals and non-metals form ionic compounds by transfer of electrons; these have high melting points and conduct when molten or in solution.
    • ✓Metals are extracted by heating, reduction with carbon after roasting/calcination, or electrolysis, depending on their reactivity, and refined electrolytically.
    • ✓Corrosion needs air and water; it is prevented by painting, galvanising, chrome plating, anodising and alloying.

    👨‍🏫 Teaching Tips

    • →Set up stations for Activities 3.1–3.6 so groups test lustre, malleability, ductility and conduction hands-on.
    • →Build the reactivity series as a ladder on the classroom wall and add each metal as its reactions are demonstrated.
    • →Use electron-dot diagrams with coloured counters to show Na and Cl forming Na⁺ and Cl⁻.
    • →Draw a single flowchart linking reactivity to the method of extraction (heat alone, carbon reduction, electrolysis).
    • →Start the three-test-tube rusting activity a week before the lesson so students see the results.
    • →Show real samples of brass, bronze, solder and stainless steel and ask students to guess their components.
    • →Discuss why 22-carat gold is used for jewellery to connect alloys with daily life.

    📋 Assessment Questions

    1. Give two examples each of metals that are exceptions to general physical properties.
    2. Why is sodium kept under kerosene?
    3. Show the formation of MgCl₂ by transfer of electrons.
    4. Differentiate between roasting and calcination with one equation each.
    5. Explain why galvanised iron does not rust even if the zinc coating is broken.

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    Keep learning

    All chapters in Science - Class 10

    1. 1. Chemical Reactions and Equations
    2. 2. Acids, Bases and Salts
    3. 3. Metals and Non-metals
    4. 4. Carbon and its Compounds
    5. 5. Life Processes
    6. 6. Control and Coordination
    7. 7. How do Organisms Reproduce?
    8. 8. Heredity
    9. 9. Light – Reflection and Refraction
    10. 10. The Human Eye and the Colourful World
    11. 11. Electricity
    12. 12. Magnetic Effects of Electric Current
    13. 13. Our Environment