CLASS 10 SCIENCE · CHAPTER 3 · STUDY NOTES
Metals and Non-metals
A comprehensive guide to the physical and chemical properties of elements, the reactivity series, ionic bonding, and the metallurgical processes used to extract and refine metals.
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Physical Properties of Metals
Match a metal’s property to its use, and distinguish shaping from conduction.SEE THE CHEMISTRY
One material. Several useful properties.
Predict: which change makes a sheet, and which makes a wire?
- Malleability
- Ability to be beaten into thin sheets.
- Ductility
- Ability to be drawn into thin wires.
A metal can be shaped without becoming a different substance. Malleability makes sheets possible; ductility makes wires possible. A clean metal surface usually has metallic lustre.
Heat conduction, electrical conduction and sonority are different properties. Copper carries current in a wire and transfers heat in a vessel; a struck metal bell vibrates and rings.
Go deeper: Why a wire has an insulating coat
The metal core carries electric current. PVC or rubber around it limits unwanted contact with the conductor; the coating does not make the metal itself a poor conductor.
Silver and copper are good heat conductors. Lead and mercury are poorer heat conductors than these metals. Hardness and melting point vary: the useful rule is a general tendency, not a definition that excludes every exception.
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Question
A designer needs a thin sheet for wrapping and a long wire for a coil. Which shaping property matters for each?
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Non-metals and Physical Exceptions
Use several properties together instead of classifying an element from one clue.SEE THE CHEMISTRY
Look beyond a single property.
Compare: can shine or conductivity alone identify a metal?
- Allotrope
- A different structural form of the same element.
| Clue | Why it is insufficient alone |
|---|---|
| Shiny surface | Iodine is a shiny non-metal. |
| Liquid at room temperature | Mercury is a metal; bromine is a non-metal. |
| Conducts electricity | Graphite is a non-metal. |
| Soft enough to cut | Sodium is a metal. |
Graphite and diamond both contain carbon. Graphite conducts electricity; diamond is very hard. Their different structures produce different properties without turning either into a metal.
Iodine is a shiny non-metal. Mercury is a liquid metal; bromine is a liquid non-metal at room temperature. Sodium is a soft metal. A single property cannot settle the classification.
Go deeper: Rules and exceptions
Most solid non-metals are brittle and poor conductors. Most metals are malleable, ductile and good conductors, but sodium and potassium are soft. Gallium and caesium have low melting points compared with many metals.
The chapter’s chemical patterns give another way to compare elements: common metals form positive ions by losing electrons, while common non-metals in ionic compounds gain electrons. These are chapter-level patterns, not a rule that every element forms only one kind of bond.
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Question
A shiny sample is labelled “metal” without further evidence. Give a reason to question that label.
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How Metals React with Oxygen
Explain oxide formation, protective coatings and amphoteric behaviour.SEE THE CHEMISTRY
An oxide can coat the surface—or protect it.
Predict: does every oxide react only with acids?
- Amphoteric oxide
- An oxide that reacts with both acids and bases to form salts and water.
Heating copper in air produces a black copper(II) oxide coating: 2Cu + O₂ → 2CuO. Aluminium also forms an oxide, but its thin, attached layer limits further attack on the metal underneath.
Most metal oxides are basic. Aluminium oxide and zinc oxide are amphoteric: they react with an acid and with a base. Insoluble does not mean unreactive.
Formation of Copper Oxide
2Cu + O₂ → 2CuOCopper metal is heated in the presence of atmospheric oxygen to produce black-colored copper(II) oxide.
Amphoteric Reaction of Aluminium Oxide
Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂OAluminium oxide acts as an acid here, reacting with the base sodium hydroxide to form sodium aluminate and water.
Go deeper: Why appearance and reaction rate differ
Sodium and potassium react vigorously with air and are stored under kerosene. Magnesium burns with a bright white flame; heated copper gains a black coating. Fine iron filings react more readily in a flame than a bulk piece.
Anodising deliberately thickens aluminium’s protective oxide. The chapter writes its base reaction as Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O and its acid reaction as Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O. Sodium and potassium oxides react with water to form alkalis; most metal oxides do not dissolve in water.
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Question
An oxide remains undissolved in water but reacts with both HCl and NaOH. Is it simply an insoluble basic oxide? Explain.
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Reaction of Metals with Water
Predict the product from the metal and the water conditions, not from reactivity alone.SEE THE CHEMISTRY
Cold water, hot water and steam are different tests.
Predict: what changes when hot liquid water is replaced by steam?
Ca + 2H₂O → Ca(OH)₂ + H₂
Hydrogen bubbles stick to the calcium or magnesium and help it float. It has not turned into a gas.
- Exothermic reaction
- A reaction that releases energy as heat to its surroundings.
Calcium reacts with cold water to form calcium hydroxide and hydrogen. Hydrogen bubbles attached to the metal help it float. Magnesium reacts noticeably with hot water in the chapter’s test.
Iron, zinc and aluminium require steam in the textbook comparison, forming oxides and hydrogen. Copper, lead, silver and gold do not react under these water-test conditions.
Iron and steam
Heated metal and steam
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)Heated iron reacts directly with steam; slow rusting in moist air is a different process.
Go deeper: Liquid water and steam are different tests
Potassium and sodium react violently with cold water, releasing enough heat for hydrogen to ignite. Calcium’s reaction is less violent. These observations belong to teacher-led laboratory demonstrations.
Hot liquid water gives Mg(OH)₂ in the magnesium example; heated iron with steam gives Fe₃O₄: 3Fe + 4H₂O(g) → Fe₃O₄ + 4H₂. This direct reaction differs from iron’s slow corrosion in moist air.
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Question
Iron appears unchanged in hot water but releases a gas in a heated steam test. Name the gas and explain why the two observations agree.
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Reaction of Metals with Acids
Predict hydrogen production while keeping the metal and acid type explicit.SEE THE CHEMISTRY
Look for the hydrogen bubbles—and the exceptions.
Predict: will the same metal release hydrogen with every acid?
Fe + 2HCl → FeCl₂ + H₂
For these cleaned metals in dilute HCl, reactivity decreases Mg > Zn > Fe; copper does not displace hydrogen. Nitric acid is an oxidising acid, so “metal + acid gives H₂” is not universal.
- Oxidising agent
- A substance that causes oxidation of another substance and is itself reduced.
Cleaned magnesium, aluminium, zinc and iron react with dilute HCl; copper does not displace hydrogen from it. For the chapter’s comparison the order is Mg > Al > Zn > Fe.
Nitric acid is an oxidising acid, so hydrogen is usually not released. Very dilute nitric acid is an exception with magnesium and manganese. “Metal plus acid” is not enough information to predict the gas.
Go deeper: Why nitric acid is a special case
NCERT explains the absence of H₂ by nitric acid’s oxidising action and its reduction to nitrogen oxides. The nitrogen-containing product depends on conditions; bubbles in a sketch must not automatically be labelled hydrogen.
Aqua regia is a concentrated HCl–HNO₃ mixture in the chapter’s 3:1 ratio and can dissolve gold and platinum. Its behaviour is different from the dilute-HCl test; it is a source example, not a preparation activity.
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Question
A student changes dilute HCl to nitric acid but leaves an H₂ label on the diagram. What information must be checked?
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The Reactivity Series and Displacement
Use the order of the series to predict a displacement and its visible evidence.SEE THE CHEMISTRY
Can this metal take another metal’s place?
Predict the reaction before opening the result.
A metal higher in the series can displace a lower one.
- Displacement reaction
- A reaction in which a more reactive element replaces a less reactive element from a compound.
An iron strip can displace copper from CuSO₄ solution. Copper deposits on the strip and FeSO₄ forms; the blue solution can become pale green as the reaction progresses.
Reversing the materials does not reverse the reaction: copper does not displace iron from FeSO₄. Hydrogen is a non-metal reference in the series, useful for predicting reactions with suitable dilute non-oxidising acids.
Iron displacing Copper
Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)Iron is more reactive than copper, so it displaces copper from the sulphate solution. The blue color of the solution fades to light green.
Go deeper: A ranking is not a reaction-speed scale
The chapter order is K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au. Equal spacing in the visual means order only, not equal energy or reaction-rate differences.
A complete conversion equation is a simplified endpoint. Visible rates and colours also depend on concentration, surface condition and time. The series predicts the direction of displacement for the chapter’s selected tests.
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Question
A zinc strip is placed in pale-green FeSO₄. A copper strip is placed in another FeSO₄ sample. Which can deposit iron, and why?
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