Metals are elements that readily lose electrons to form positive ions (cations) and exhibit properties such as high electrical and thermal conductivity, malleability, ductility, and metallic lustre.
From a chemical perspective, metals are electropositive elements that tend to form ionic compounds by donating electrons.
Physical Properties of Metals
- Mercury is liquid at room temperature.
- Sodium and Potassium are soft and can be cut with a knife.
- Gallium melts in hand (low melting point).
Chemical Properties of Metals
Reactivity of Metals
This concept is critical for understanding displacement reactions and extraction of metals.
A student observed that aluminium does not corrode easily despite being reactive.
Question: Explain why.
Solution: Aluminium forms a thin protective oxide layer (Al₂O₃) that prevents further corrosion.
This tendency explains why non-metals form anions or share electrons in covalent bonds.
Physical Properties of Non-Metals
- Graphite conducts electricity.
- Iodine is lustrous.
- Diamond is extremely hard (hardest natural substance).
Chemical Properties of Non-Metals
Covalent Bonding in Non-Metals
Carbon exists as both diamond and graphite with very different properties.
Question: Explain the reason.
Solution: Due to different atomic arrangements (allotropes), graphite has free electrons (conductive) while diamond has a rigid 3D structure (non-conductive and very hard).
Difference between Metals and Non-Metals
| metals | Non-Metals |
|---|---|
| Mostly solids at room temperature (exception: mercury) | Exist in all three states (solid, liquid, gas) |
| Generally hard (exceptions: sodium, potassium are soft) | Generally soft (exception: diamond is extremely hard) |
| Malleable and ductile | Brittle and non-ductile |
| Lustrous (shiny surface) | Non-lustrous (exception: iodine) |
| Good conductors of heat and electricity | Poor conductors (exception: graphite) |
| Electropositive (lose electrons easily) | Electronegative (gain electrons) |
| Form basic or amphoteric oxides | Form acidic or neutral oxides |
| High melting and boiling points | Low melting and boiling points |
| High density | Low density |
| Sonorous (produce sound when struck) | Non-sonorous |
| Form ionic compounds | Form covalent compounds |
Concept Map for Quick Revision
Key Electron Transfer Concept
A material is shiny, conducts electricity, and can be beaten into thin sheets.
Question: Classify it and justify.
Solution: It is a metal because it shows lustre, conductivity, and malleability.
Important Exceptions with Scientific Reason
Mercury (Hg)
Reason: Weak metallic bonding due to larger atomic size reduces intermolecular attraction.
Gallium (Ga) and Caesium (Cs)
Reason: Weak metallic bonds due to loosely held valence electrons.
Iodine (I)
Reason: Its crystal structure reflects light like metals.: A non-metal that shows lustre.
Reason: Its crystal structure reflects light like metals.
Diamond
Reason: Strong 3D covalent network structure.
Graphite (C)
Reason: Presence of free electrons between carbon layers.
Alkali Metals (Li, Na, K)
Reason: Only one valence electron → weak metallic bonding.
A student observes that carbon conducts electricity in one form but not in another.
Question: Explain this behavior.
Solution: Graphite conducts electricity due to free electrons, whereas diamond does not because all electrons are involved in strong covalent bonds.
Formation of metal oxide
Metals react with oxygen to form metal oxides, which are generally basic in nature.
\[\small\color{orange}\boxed{\text{Metal} + \text{Oxygen} \rightarrow \text{Metal Oxide}}\]
Amphoteric Oxides
Formation of Alkalis
Highly reactive metals like sodium and potassium react vigorously with oxygen and are stored in kerosene.
Reaction with Dilute Acids
Metals react with dilute acids to produce salt and hydrogen gas.
\[\scriptsize\color{orange}\boxed{\mathrm{Metal + Dilute Acid \rightarrow Salt + H_2}}\]
\[ \mathrm{Zn + 2HCl \rightarrow ZnCl_2 + H_2} \]
- Metals like Cu, Ag, Au do not react with dilute acids.
- Nitric acid (HNO₃) usually does not produce H₂ gas due to its oxidising nature.
Reaction with Water</h3>
Types of Reactions
Displacement Reactions
A more reactive metal displaces a less reactive metal from its compound.
\[\scriptsize\color{orange}\boxed{\mathrm{A + B^{+} \rightarrow A^{+} + B}}\]
\[ \mathrm{Zn + CuSO_4 \rightarrow ZnSO_4 + Cu} \]
This reaction is used to determine the reactivity series.
Core Chemical Principle
A metal X displaces copper from CuSO₄ solution but does not react with water.
Question: Identify its reactivity.
Solution: Metal X is more reactive than Copper (as it successfully displaces it) but less reactive than Magnesium (as it fails to react with water). This places X in the middle of the reactivity series, likely being a metal like Iron (Fe) or Lead (Pb)..
Reactivity Series (Most to Least Reactive)
- Potassium (K)
- Sodium (Na)
- Calcium (Ca)
- Magnesium (Mg)
- Aluminium (Al)
- Zinc (Zn)
- Iron (Fe)
- Lead (Pb)
- Copper (Cu)
- Silver (Ag)
- Gold (Au)
Displacement Rule
Importance in Extraction of Metals
A metal X displaces iron from FeSO₄ but does not react with sodium hydroxide.
Question: Where is X placed in the reactivity series?
Solution: X is more reactive than iron but less reactive than sodium.
Definition of Ionic Compounds
Stepwise Formation of Ionic Bond
- \[\mathrm{Na} \rightarrow \mathrm{Na^+ + e^-}\]
- \[\mathrm{Cl + e^-} \rightarrow \mathrm{Cl^-}\]
- \[\mathrm{Na^+ + Cl^-} \rightarrow \mathrm{NaCl}\]
This transfer leads to formation of oppositely charged ions held by strong electrostatic forces.
Ionic Lattice Structure
Properties of Ionic Compounds
A compound does not conduct electricity in solid state but conducts in molten form.
Question: Identify the type of compound.
Solution: It is an ionic compound because ions are fixed in solid state but free in molten state.
Extraction of Low Reactivity Metals
Roasting and Calcination
Extraction of Moderately Reactive Metals
Thermite Reaction (Aluminothermy)<
Extraction of Highly Reactive Metals
Methods of Refining
-
⚡Electrolytic Refining
-
⚗️Distillation
-
💧Liquation
-
🌀Zone Refining
Electrolytic Refining
In this method, impure metal is used as the anode, pure metal as the cathode, and a suitable salt solution as the electrolyte.
Electrode Reactions
\[ \begin{aligned} \text{At Anode: } &\mathrm{M \rightarrow M^{n+} + ne^-} \ \text{At Cathode: } &\mathrm{M^{n+} + ne^- \rightarrow M} \end{aligned} \]
- Impure metal is taken as anode
- Pure metal strip is cathode
- Electrolyte contains metal salt solution
- On passing current, metal dissolves from anode
- Pure metal deposits on cathode
- Impurities settle as anode mud
Copper Refining
Electrolyte: Acidified CuSO₄ solution
Anode: Impure copper
Cathode: Pure copper sheet
Advantages of Electrolytic Refining
- Barrier Protection (Painting, Oiling, Greasing): Prevents contact with air and moisture.
- Galvanisation: Coating iron with zinc. Zinc acts as a sacrificial metal.
- Alloying: Stainless steel (Fe + Cr + Ni) resists corrosion due to protective oxide layer.
- Cathodic Protection: More reactive metal (Zn, Mg) corrodes instead of iron.
Zinc is more reactive than iron, so it oxidises first:
\[ \mathrm{Zn \rightarrow Zn^{2+} + 2e^-} \]
Thus, iron is protected even if the coating is damaged.
Metals & Non-Metals
An interactive learning engine for deep conceptual mastery
Eight foundational pillars of Chapter 3 — click any card to explore
Physical Properties of Metals
Metals are lustrous, malleable, ductile, and good conductors of heat and electricity. They are generally hard solids with high melting and boiling points.
Physical ChemistryPhysical Properties of Non-Metals
Non-metals are brittle, non-lustrous, poor conductors (except graphite), with low melting points. They may be solids, liquids, or gases.
Physical ChemistryReaction of Metals with Oxygen
Most metals react with oxygen to form basic metallic oxides. The reactivity determines speed and conditions required for oxide formation.
Chemical ReactionsReactivity Series of Metals
An ordered arrangement of metals based on decreasing reactivity. Helps predict the outcome of displacement reactions and metal extraction methods.
ElectrochemistryIonic Bonding in Metals
Metals tend to lose electrons and form cations. Non-metals gain electrons to form anions. The electrostatic attraction between ions forms ionic bonds.
Chemical BondingExtraction of Metals (Metallurgy)
Metals occur as ores in the earth's crust. Extraction involves concentration, reduction (for medium-activity metals), and electrolytic reduction (for highly reactive metals).
Industrial ChemistryCorrosion and Its Prevention
Corrosion is the slow destruction of metals due to reaction with air, moisture, and chemicals. Rusting of iron is the most common example.
Applied ChemistryAlloys — Composition & Uses
An alloy is a homogeneous mixture of two or more metals (or metal + non-metal) with enhanced properties compared to constituent elements.
Materials ScienceAll major reactions with conditions, products and observation notes
Reactions with Water
Mg + H2O → MgO + H2↑ (steam)
Reactions with Dilute Acids
Displacement Reactions
Reactions of Non-Metals
N2 + 2O2 → 2NO2↑ (Acidic oxide)
C + O2 → CO2↑ (Acidic oxide)
Mg + Cl2 → MgCl2
2K + S → K2S
Side-by-side analysis for quick revision and conceptual clarity
Metals vs Non-Metals — Physical Properties
| Property | Metals | Non-Metals |
|---|---|---|
| Physical State | Mostly solids (except Hg — liquid) | Solids, liquids (Br₂), or gases |
| Lustre | Shiny metallic lustre | Dull (except Iodine, Graphite) |
| Hardness | Generally hard (except Na, K) | Soft (except Diamond — hardest) |
| Malleability | Malleable (beaten into sheets) | Brittle; break into pieces |
| Ductility | Ductile (drawn into wires) | Not ductile |
| Conductivity | Good conductors of heat & electricity | Poor conductors (except Graphite) |
| Melting/Boiling Point | High (except Hg, Ga, Cs) | Low (except Diamond, Silicon) |
| Density | High (except Na, K, Li) | Low |
| Sonority | Sonorous (produce sound when struck) | Not sonorous |
Metals vs Non-Metals — Chemical Properties
| Reaction | Metals | Non-Metals |
|---|---|---|
| With Oxygen | Metal + O₂ → Basic oxide | Non-metal + O₂ → Acidic oxide |
| With Water | Reactive metals form H₂ + base | Halogens dissolve; Cl₂ + H₂O → HCl + HClO |
| With Acids | Form salt + H₂ ↑ (if above H) | Do not react with acids generally |
| With Chlorine | Form ionic chlorides (MCl) | Form covalent chlorides (e.g., PCl₃) |
| Electron Tendency | Lose electrons → form cations | Gain electrons → form anions |
| Bond Type Formed | Ionic bonds with non-metals | Covalent bonds with non-metals |
| Nature of Oxide | Basic (turns red litmus blue) | Acidic (turns blue litmus red) |
Ionic Compounds vs Covalent Compounds
| Property | Ionic Compounds | Covalent Compounds |
|---|---|---|
| Bond Formation | Electrostatic attraction between ions | Sharing of electrons |
| Melting/Boiling Point | High | Generally low |
| Solubility in Water | Generally soluble | Generally insoluble (except polar) |
| Electrical Conductivity | Conduct in molten/aqueous state | Generally non-conductors |
| State at Room Temp | Solid crystals | May be solid, liquid or gas |
| Example | NaCl, MgCl₂, CaO | HCl, CO₂, H₂O, CCl₄ |
Metals and Reactivity with Water — Summary
| Metal | Condition | Product | Reactivity |
|---|---|---|---|
| Na, K | Cold water | MOH + H₂↑ | Very high |
| Ca | Cold water | Ca(OH)₂ + H₂↑ | High |
| Mg | Hot water / steam | MgO + H₂↑ | Moderate |
| Al, Zn, Fe | Steam only | Metal oxide + H₂↑ | Moderate–low |
| Pb | Steam (slowly) | PbO + H₂↑ | Low |
| Cu, Ag, Au, Pt | No reaction | — | Negligible |
Select a question type or type your own — get a full step-by-step solution
Original questions (not from textbook) — organised by concept, with full solutions
-
Understand the question: Why is Cu chosen over other conductors? We need properties, not just electrical conductance.
-
Property 1 — Electrical conductivity: Copper has the second highest electrical conductivity among metals (after silver), making current flow with minimal resistance. Silver is too expensive; hence copper is the practical choice.
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Property 2 — Ductility: Copper is highly ductile — it can be drawn into very thin wires without breaking. This is essential for wire manufacture. Iron is less ductile and more brittle.
-
Bonus — Corrosion resistance: Copper does not rust like iron. It forms a thin protective green patina (CuCO₃·Cu(OH)₂) that prevents further corrosion, extending wire life.
-
Conclusion: Copper's exceptional ductility + high conductivity + corrosion resistance make it the optimal practical choice for wiring, even though silver is a better conductor.
-
Recall reactivity series: K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag
-
Case 1 — Zn in AgNO₃: Zn is MORE reactive than Ag. ∴ Zn displaces Ag from solution.
Zn + 2AgNO₃ → Zn(NO₃)₂ + 2Ag↓
Colourless AgNO₃ → colourless Zn(NO₃)₂; grey-white silver deposits on zinc. -
Case 2 — Zn in CuSO₄: Zn is MORE reactive than Cu. ∴ Zn displaces Cu.
Zn + CuSO₄ → ZnSO₄ + Cu↓
Blue CuSO₄ solution becomes colourless; reddish-brown Cu deposits on zinc. -
Generalisation: A more reactive metal always displaces a less reactive metal from its salt solution. This is the basis of displacement reactions.
-
Apparent contradiction: If Al is more reactive, it should corrode faster — so why is it used where corrosion resistance is needed?
-
The key — Passive layer (Anodisation): When Al is exposed to air, it immediately reacts with oxygen to form a thin, impermeable layer of aluminium oxide:
4Al + 3O₂ → 2Al₂O₃ -
Why this protects: Al₂O₃ is hard, tightly adherent, and chemically inert. It acts as a physical barrier, preventing further oxygen and moisture from reaching the underlying metal — so corrosion stops after a thin film forms.
-
Contrast with iron: Iron oxide (Fe₂O₃·xH₂O — rust) is porous and flakes off, continuously exposing fresh iron. Iron corrodes layer by layer until the entire piece is destroyed.
-
Other advantages of Al: Low density (light-weight, essential for aircraft); high strength-to-weight ratio; good thermal conductivity (cooking utensils).
-
Conclusion: Al's self-passivating property makes it effectively corrosion-resistant in practical applications, despite being chemically reactive.
-
Step 1 — Na reacts with O₂:
4Na + O₂ → 2Na₂O
Sodium burns with a bright yellow-orange flame. Product: Sodium oxide (Na₂O), a white solid. (Na can also form Na₂O₂ with excess O₂.) -
Step 2 — Na₂O dissolves in water:
Na₂O + H₂O → 2NaOH
The white solid dissolves, forming sodium hydroxide — a strong alkali. Solution becomes warm (exothermic). -
Step 3 — Litmus test: NaOH is strongly alkaline (pH ≈ 12–13). Red litmus paper turns blue. Blue litmus remains blue.
-
Step 4 — Phenolphthalein test: Phenolphthalein is colourless in neutral/acidic solutions and pink/magenta in alkaline solutions. Solution turns bright pink. This confirms strong alkalinity.
-
Key Concept Link: Metal → Metal oxide (basic) → Metal hydroxide (alkali) in water. This confirms that metallic oxides are basic in nature.
-
Structure of ionic compounds: NaCl has Na⁺ and Cl⁻ ions arranged in a regular 3D lattice. Each Na⁺ is surrounded by 6 Cl⁻ ions and vice versa (face-centred cubic structure).
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High melting point: Millions of strong electrostatic attractions (Na⁺ ← → Cl⁻) hold the lattice together. Enormous energy is needed to break these bonds simultaneously → very high melting point (801°C for NaCl).
-
No conductivity in solid state: In solid NaCl, ions are held rigidly in fixed positions in the lattice. They cannot move. No movement of charge = no current flow.
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Conductivity in molten/aqueous state: On melting (or dissolving), the lattice breaks down. Ions become free to move. When electrodes are placed, Na⁺ migrates to cathode and Cl⁻ to anode — current flows.
-
Conclusion: Conductivity in ionic compounds requires mobile ions. Solid state = immobile ions = insulator. Liquid/aqueous = mobile ions = conductor.
-
Interpret observations: Ease of reaction with acids indicates position in reactivity series. More reactive metals react faster under milder conditions.
-
Analysis:
• A reacts vigorously with cold HCl → Very reactive → Above Mg in series → e.g., Na or Mg
• B reacts only on heating → Moderate reactivity → e.g., Fe or Zn
• C does not react → Below H in series → e.g., Cu -
Order: A > B > C in reactivity.
-
Representative equations:
Mg + 2HCl → MgCl₂ + H₂↑ (A)
Fe + 2HCl → FeCl₂ + H₂↑ (B, on heating)
Cu + HCl → No reaction (C)
-
Chemistry of rusting (electrochemical process):
4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃ → 2Fe₂O₃·3H₂O (rust)
Rust is hydrated iron(III) oxide — orange-brown, porous, and non-adherent. It flakes off, exposing fresh iron. -
Why pure iron rusts so fast: Fe readily loses electrons (Fe → Fe²⁺) in the presence of moisture. Water acts as an electrolyte, accelerating the electrochemical reaction. Rust is non-protective and keeps falling off.
-
How stainless steel prevents rust: Adding chromium (Cr, ~10–18%) creates an alloy where Cr reacts with O₂ to form Cr₂O₃ — a thin, invisible, adherent, non-porous passive film — preventing Fe from reacting with air/moisture. Nickel adds toughness.
-
Other prevention methods for bridges:
① Galvanisation: Coat iron with zinc. Zn is more reactive — it acts as a sacrificial anode; even if coating chips, Zn corrodes first, protecting Fe.
② Painting / Cathodic Protection: Apply anti-rust paints (containing zinc chromate or red lead). For bridges, connect to an external DC source making bridge the cathode (cathodic protection).
-
Part (a) — Why not aqueous NaCl? In aqueous solution, both Na⁺ and H⁺ (from water ionisation: H₂O ⇌ H⁺ + OH⁻) are present at the cathode. Since H⁺ is easier to reduce than Na⁺ (H has lower reduction potential), H₂ gas is produced at cathode, NOT sodium metal. Na is far too reactive; it would immediately react with water: 2Na + 2H₂O → 2NaOH + H₂↑
-
Part (b) — Na collected at cathode: Cathode is the negative electrode; it attracts positive ions (cations). Na⁺ ions migrate to cathode and gain electrons:
Na⁺ + e⁻ → Na (reduction)
At anode (positive), Cl⁻ ions lose electrons:
2Cl⁻ → Cl₂↑ + 2e⁻ (oxidation) -
Mnemonic: OILRIG — Oxidation Is Loss, Reduction Is Gain of electrons. Anode = oxidation; Cathode = reduction. Positive ions (Na⁺) go to cathode (negative electrode).
Memory aids, shortcuts, and exam strategies curated from the chapter
🔑 Memory Aids & Mnemonics
Reactivity Series Mnemonic
"King Narendra Can Make A Zebra Feel Pretty Hot, Considering His Actual Greatness Particularly"
K · Na · Ca · Mg · Al · Zn · Fe · Pb · H · Cu · Hg · Ag · Au · Pt
OILRIG — Electrochemistry Core
Oxidation Is Loss, Reduction Is Gain (of electrons). Anode = Oxidation (A–O), Cathode = Reduction. Works for electrolysis and displacement reactions alike.
Oxide Nature → Litmus Trick
Metal oxides are Basic → turns Red litmus Blue (B comes after R — basic follows the metal).
Non-metal oxides are Acidic → turns Blue litmus Red.
Exceptions to Memorise (1 mark questions!)
• Liquid metal at RT → Mercury (Hg)
• Liquid non-metal at RT → Bromine (Br₂)
• Non-metal conductor → Graphite (Carbon)
• Metal cut by knife → Na, K, Li (very soft)
• Lustrous non-metal → Iodine
• Hardest natural substance → Diamond (Carbon)
Alloy Composition Quick-Recall
Brass = Cu + Zn (Z = Zinc; Brass rhymes with "class" → elegant, used in musical instruments)
Bronze = Cu + Sn (Bronze age = old; Sn = ancient symbol for tin)
Solder = Pb + Sn (think "Pbond + Snap together" — welding)
Exam Strategy: Reaction with Water Questions
Always state: (1) the condition (cold water / hot water / steam / no reaction), (2) the products, (3) write the balanced equation. For full marks, mention the observation (e.g., vigorous effervescence, Na floats and moves).
Fe₃O₄ vs Fe₂O₃ — Don't Mix Them Up!
Fe₃O₄ (black magnetic oxide) — formed when iron reacts with steam or burns in oxygen: 3Fe + 4H₂O → Fe₃O₄ + 4H₂
Fe₂O₃ (hydrated form = rust) — formed by slow corrosion with air + moisture: 4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃ → Fe₂O₃·3H₂O
Why Gold & Platinum are "Noble" Metals
They are at the bottom of the reactivity series — lowest tendency to lose electrons. They do not react with air, water, dilute acids, or most chemicals. This is why gold jewellery doesn't tarnish and platinum is used in catalytic converters.
Frequently made errors in exams — learn what's wrong and why
Confusing Malleability with Ductility
Memory: Ductile → Draw (both start with D). Malleable → Mallet (hammering).
Writing Wrong Formula for Rust
Rust requires both oxygen AND water. Neither alone causes rusting. Always write the hydrated form.
Thinking Copper Reacts with Dilute HCl
Cu cannot displace H from dilute HCl/H₂SO₄. It does react with concentrated HNO₃ and hot conc. H₂SO₄ — but those are not dilute acids.
Saying "All metals are solid at room temperature"
Gallium (Ga) melts at ~29.8°C and becomes liquid on your palm — also an exception!
Confusing Anodising with Galvanisation
Galvanisation is named after Luigi Galvani, uses zinc because Zn is more reactive than Fe — acts as sacrificial metal.
Wrong Product: Iron + Steam
Fe₃O₄ is a mixture of FeO and Fe₂O₃ — it's the black magnetic oxide formed at high temperature. Iron does NOT react with cold or hot water.
Thinking Ionic Compounds Conduct in Solid State
Conductivity requires mobile charge carriers. In solid ionic compounds, ions are stationary. Only molten or dissolved ionic compounds conduct.
Mixing Brass and Bronze
Trick: Brass has a 'Z' (Zinc). Bronze has an 'n' → Tin (Sn comes from Latin Stannum). Bronze Age weapons were made of Cu+Sn — the stronger alloy.
Six activity types for active recall and concept reinforcement
MCQ Quiz
10 randomised multiple-choice questions with instant feedback and explanations
Match the Columns
Connect metals to their reactions, properties, or alloys
Fill in the Blanks
Complete the chemical equations and statements
Reactivity Sorter
Drag-and-rank metals by reactivity; verify against the actual series
True or False
15 quick statements — decide, then see the explanation
Flash Cards
Flip cards for key terms, reactions, and alloy compositions
Match the Columns
Click an item in Column A, then click the matching item in Column B.
Fill in the Blanks
Complete each statement or equation with the correct term.
Reactivity Sorter
Drag the metals to arrange them from MOST reactive (top) to LEAST reactive (bottom).
True or False
Flash Cards — Click to Flip
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Metals and Non-Metals — Learning Resources
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