Metals & Nonmetals

Introduction: The Elements That Build Our World

Metals are the backbone of civilization. From the Iron Age to the Silicon Age, human progress is written in the elements. They forge tools, conduct electricity, build skyscrapers, and power technologies. Nonmetals, equally essential, form gases we breathe, liquids we drink, and the very fabric of living matter. Understanding metals and nonmetals—their properties, extraction, reactivity, and applications—is essential for competitive exams and understanding industrial chemistry.

Part 1: Physical and Chemical Properties

Metals

Physical Properties:

• Luster (shine): Reflect light (except when oxidized)
• Malleability: Can be hammered into thin sheets without breaking
• Ductility: Can be drawn into wires
• High density: Most are dense (except alkali metals)
• High melting/boiling points: Generally high; mercury (Hg) is exception (liquid at room temp)
• Electrical conductivity: Conduct electricity due to delocalized electrons
• Thermal conductivity: Conduct heat efficiently
• Sonority: Produce sound when struck

Chemical Properties:

• Lose electrons: Tend to lose electrons and form positive ions (cations)
• Oxidation states: Usually positive
• Metallic bonding: Electrons form a "sea" throughout the structure
• React with nonmetals: Form ionic or covalent compounds

Example: Sodium (Na)

• Soft, silvery metal; can be cut with a knife
• Low density; floats on water (but reacts explosively)
• Excellent electrical conductor
• Very reactive; loses its valence electron easily (Na → Na⁺ + e⁻)

Nonmetals

Physical Properties:

• Dull appearance: Don't reflect light (except diamond and graphite)
• Brittle (as solids): Break when struck (solid nonmetals)
• Low density: Generally lighter than metals
• Low melting/boiling points: Many are gases or liquids at room temp
• Poor electrical conductivity: Don't conduct electricity (except graphite)
• Poor thermal conductivity: Don't conduct heat well

Chemical Properties:

• Gain or share electrons: Accept electrons or share them covalently
• Oxidation states: Usually negative or variable (depending on bonding partner)
• Covalent bonding: Form molecules by sharing electrons
• React with metals: Form ionic or covalent compounds

Example: Chlorine (Cl₂)

• Yellow-green gas with pungent smell
• Highly toxic
• Excellent oxidizing agent; gains electrons easily (Cl₂ + 2e⁻ → 2Cl⁻)
• Reacts vigorously with metals and other nonmetals

[Memory Hook] Metals: shiny, conduct, malleable, lose electrons. Nonmetals: dull, poor conductors, brittle, gain/share electrons.

Part 2: Reactivity Series (Activity Series)

The reactivity series arranges elements in order of their tendency to lose electrons (or gain them, for nonmetals).

Metals (Reactivity Series)

From most to least reactive:

K > Na > Ca > Mg > Al > Zn > Fe > Cu > Ag > Au

Groups by reactivity:

Reactivity	Metals	Characteristics
Very High	Alkali metals (K, Na, Li)	Lose electrons extremely easily; very reactive
High	Alkaline earth metals (Ca, Mg, Ba)	Lose electrons easily; quite reactive
Medium	Transition metals (Al, Zn, Fe)	Lose electrons moderately; useful for most applications
Low	Less reactive (Cu, Ag, Au)	Lose electrons reluctantly; very unreactive

Applications:

• Highly reactive metals (K, Na): Used in rocket fuels, nuclear reactions
• Medium reactivity (Mg, Al, Fe, Zn): Structural metals, engines, tools
• Low reactivity (Cu, Ag, Au): Jewelry, coins, electrical wiring

[Memory Hook] K and Na most reactive; Au and Ag least reactive; transition metals in middle

Nonmetals (Reactivity Series, Halogens)

From most to least reactive:

F₂ > Cl₂ > Br₂ > I₂

Fluorine is the most reactive element overall (most eager to gain electrons).

Displacing each other:

• Cl₂ displaces Br⁻ from its compounds: Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂
• Cl₂ displaces I⁻ from its compounds: Cl₂ + 2I⁻ → 2Cl⁻ + I₂
• Br₂ cannot displace Cl⁻ (Cl is more reactive)

Part 3: Extraction of Metals from Ores

Step 1: Ore Selection and Concentration

An ore is a naturally occurring mineral containing enough metal to be economically extracted.

Indian ore sources:

Metal	Ore	Primary State	Annual Production
Iron (Fe)	Hematite (Fe₂O₃), Magnetite (Fe₃O₄)	Jharkhand, Odisha	~50 million tons
Aluminum (Al)	Bauxite (Al₂O₃·3H₂O)	Odisha (90%)	~20 million tons
Copper (Cu)	Chalcopyrite (CuFeS₂), Malachite	Rajasthan, Karnataka	~600,000 tons
Zinc (Zn)	Sphalerite (ZnS)	Rajasthan, Gujarat	~1 million tons
Manganese (Mn)	Pyrolusite (MnO₂)	Madhya Pradesh, Odisha	~2 million tons
Lead (Pb)	Galena (PbS)	Rajasthan	~70,000 tons
Chromium (Cr)	Chromite (FeCr₂O₄)	Odisha	~150,000 tons

Concentration methods:

• Magnetic separation: Separates magnetic ores (magnetite) from gangue (worthless rock)
• Froth flotation: Separates sulfide ores (like chalcopyrite) using detergent foam
• Gravity separation: Heavier ore particles sink; lighter gangue floats

Step 2: Roasting (for Sulfide Ores)

Roasting: Heating sulfide ores in air to convert them to oxides.

Example: Chalcopyrite roasting

2CuFeS₂ + O₂ → Cu₂S + 2FeS + SO₂

The sulfur escapes as SO₂ gas (pollutant; causes acid rain if not captured).

Step 3: Reduction (Getting Metal from Oxide)

Method A: Carbon Reduction (for Fe, Zn, Cu)

Example: Iron extraction from hematite

2Fe₂O₃ + 3C → 4Fe + 3CO₂ (in a blast furnace)

Carbon is oxidized (loses electrons); iron oxide is reduced (gains electrons).

Limitations: Only works if metal is less reactive than carbon.

• Iron: can be reduced by carbon ✓
• Aluminum: CANNOT be reduced by carbon ✗ (aluminum is more reactive)

Method B: Electric Reduction (for Highly Reactive Metals)

Example: Aluminum extraction from bauxite

2Al₂O₃ → 4Al + 3O₂ (by electrolysis in molten solution)

Electrons are forced to transfer by electrical current.

Why electricity? Aluminum is too reactive to be reduced by carbon. Electrolysis uses electrical energy to "push" electrons into aluminum.

Method C: Displacement by More Reactive Metal

Example: Copper from copper sulfate using iron

CuSO₄ + Fe → FeSO₄ + Cu

Iron (more reactive) displaces copper (less reactive).

Step 4: Purification

Electrolytic refining: Impure metal is purified by electrolysis.

Setup:

• Impure metal = anode (positive electrode)
• Pure metal = cathode (negative electrode)
• Electrolyte = salt solution of the metal

Process:

• Impure metal at anode oxidizes: M → M⁺ + e⁻ (impurities either fall as "anode mud" or dissolve)
• Ions migrate to cathode and reduce: M⁺ + e⁻ → M (pure metal deposits)

[Memory Hook] Ore extraction: concentration → roasting (sulfides) → reduction → purification

Part 4: Corrosion and Prevention

Rusting of Iron

Rusting: Iron oxidizes to form iron oxide (Fe₂O₃·xH₂O), a red-brown coating that's porous and non-protective.

Conditions needed:

1. Oxygen: Oxygen oxidizes Fe to Fe³⁺
2. Water: Creates electrolytic environment
3. Moisture: Provides medium for electron transfer

Chemical equations:

• Fe → Fe²⁺ + 2e⁻ (oxidation at anode)
• O₂ + 2H₂O + 4e⁻ → 4OH⁻ (reduction at cathode)
• Fe²⁺ + 2OH⁻ → Fe(OH)₂ (precipitate)
• 4Fe(OH)₂ + O₂ + 2H₂O → 4Fe(OH)₃ (oxidation to Fe³⁺)
• 2Fe(OH)₃ → Fe₂O₃ + 3H₂O (dehydration to rust)

Prevention of Rusting

Method 1: Barrier Coating

Paint or enamel: Creates physical barrier preventing O₂ and H₂O access

• Example: Painted bridges, cars

Oil/grease coating: Prevents water contact

• Example: Machine parts, bicycle chains

Method 2: Galvanization

Zinc coating: Iron is coated with zinc (Zn is more reactive).

Process:

• Hot-dip galvanizing: Dip iron in molten zinc
• Electroplating: Electrolytically coat iron with zinc

Protection:

• Zinc oxidizes first (sacrificial anode): Zn → Zn²⁺ + 2e⁻
• Even if coating scratches, zinc protects underlying iron

Example: Zinc-coated steel roofing sheets (common in India)

Method 3: Alloying

Stainless steel: Iron alloyed with chromium (Cr) and nickel (Ni)

• Chromium forms a protective oxide layer (Cr₂O₃)
• This layer is non-porous and self-healing
• Example: Kitchen utensils, surgical instruments

Method 4: Cathodic Protection

Sacrificial anode: Attach a more reactive metal (Zn, Mg) to iron.

Process:

• Sacrificial metal oxidizes instead of iron
• More reactive metal becomes anode; iron becomes cathode (protected)
• Example: Zinc plates attached to ship hulls

[Memory Hook] Galvanization = coat with zinc; sacrificial anode = more reactive metal oxidizes first; stainless steel = alloy with Cr

Part 5: Alloys

An alloy is a mixture (not pure compound) of two or more elements where at least one is a metal.

Common Alloys

Alloy	Composition	Properties	Use
Brass	Cu + Zn (20-40%)	Hard, bright, low corrosion	Ornaments, valves, fittings
Bronze	Cu + Sn (5-12%)	Hard, corrosion-resistant	Sculptures, bells, bearings
Steel	Fe + C (0.1-2%) + other elements	Stronger than iron, less brittle	Structures, tools, vehicles
Stainless Steel	Fe + Cr (10-30%) + Ni + other	Corrosion-resistant	Kitchen utensils, medical tools
Duralumin	Al + Cu + Mg + Mn	Lightweight, strong	Aircraft bodies
Pewter	Sn + Cu + Ag	Soft, bright appearance	Decorative items

Why alloys?

• Increased hardness: Metal atoms of different sizes distort lattice, making it harder
• Increased strength: Prevents easy slipping of atomic layers
• Altered melting point: Alloys often melt at lower temperatures than pure metals
• Improved corrosion resistance: Alloying elements protect against rust

[Memory Hook] Alloys: mixtures of metals; harder and often less reactive than pure metals

Part 6: Nonmetals - Properties and Uses

Nitrogen (N)

• State: Colorless, odorless gas
• Reactivity: Relatively inert (N≡N triple bond is very strong)
• Uses:
  • Haber process: N₂ + 3H₂ ⇌ 2NH₃ (produces ammonia for fertilizers)
  • Fertilizers: NH₄NO₃ (ammonium nitrate), (NH₄)₂SO₄
  • Food preservation: Inert atmosphere prevents oxidation
  • Liquid nitrogen: Cryogenic applications

Oxygen (O)

• State: Colorless, odorless gas
• Reactivity: Very reactive; strong oxidizing agent
• Uses:
  • Respiration: Organisms use O₂ for energy
  • Combustion: Fuels burn in oxygen
  • Welding: Oxy-acetylene torches
  • Medical: Oxygen therapy for hypoxia

Sulfur (S)

• State: Yellow solid at room temperature
• Uses:
  • Sulfuric acid production: S + O₂ → SO₂ → SO₃ → H₂SO₄
  • Vulcanization of rubber: Sulfur cross-links rubber polymers
  • Fertilizers: Ammonium sulfate (NH₄)₂SO₄
  • Pesticides and fungicides

Halogens (F, Cl, Br, I)

• Reactivity: F₂ > Cl₂ > Br₂ > I₂ (decreases down group)

• Chlorine (Cl):

  • Disinfection: Kills bacteria in water and pools
  • PVC production: Vinyl chloride polymerization
  • Bleaching: Cl₂ + H₂O → HCl + HClO (hypochlorous acid bleaches)

• Iodine (I):

  • Medical: Antiseptic for wounds
  • Medical imaging: Contrast dye in X-rays
  • Table salt iodization: Prevents iodine deficiency

Noble Gases (He, Ne, Ar, Kr, Xe)

• Reactivity: Virtually inert (complete valence shell)
• Uses:
  • Neon (Ne): Neon lights (characteristic orange-red glow)
  • Argon (Ar): Welding gas, inert atmosphere, light bulb fill
  • Helium (He): Balloons (less dense than air), deep-sea diving (mixed with O₂)
  • Xenon (Xe): High-intensity discharge lamps

Conclusion

Metals and nonmetals are the elements that build our world. Understanding their properties, reactivity, extraction, and uses is essential for competitive exams and real-world applications. From the iron in your blood to the oxygen you breathe, from the copper in your home wiring to the aluminum in aircraft, these elements permeate civilization.

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23 MCQ Questions

Q1: Which of the following is NOT a property of metals?

• A) Malleability
• B) High electrical conductivity
• C) Brittleness as solid
• D) Luster

Q2: In the reactivity series of metals, which is the most reactive?

• A) Iron (Fe)
• B) Sodium (Na)
• C) Copper (Cu)
• D) Silver (Ag)

Q3: Which of the following metals CAN be reduced from its oxide using carbon?

• A) Aluminum (Al)
• B) Magnesium (Mg)
• C) Iron (Fe)
• D) Sodium (Na)

Q4: Why cannot carbon reduce aluminum oxide (Al₂O₃) to aluminum?

• A) Aluminum is too reactive
• B) Aluminum is less reactive than carbon
• C) Carbon doesn't reach high temperatures
• D) The reaction is reversible

Q5: Bauxite is the ore of which metal?

• A) Iron
• B) Copper
• C) Aluminum
• D) Zinc

Q6: Which state in India is the largest producer of bauxite (90% of national supply)?

• A) Jharkhand
• B) Rajasthan
• C) Odisha
• D) Madhya Pradesh

Q7: Rusting of iron requires all of the following EXCEPT:

• A) Oxygen
• B) Water/moisture
• C) Carbon dioxide
• D) All are required

Q8: In galvanization, zinc protects iron because:

• A) Zinc forms a non-porous oxide
• B) Zinc is less reactive than iron
• C) Zinc is more reactive and oxidizes instead of iron
• D) Zinc fills iron pores

Q9: Stainless steel is corrosion-resistant because:

• A) Steel doesn't contain iron
• B) Chromium forms a protective oxide layer (Cr₂O₃)
• C) Nickel prevents all oxidation
• D) It is coated with paint

Q10: Which of the following is an alloy?

• A) Pure copper
• B) Pure iron
• C) Brass (Cu + Zn)
• D) Carbon

Q11: Bronze is a better material for bearing surfaces than pure copper because:

• A) It conducts electricity better
• B) It is harder and stronger
• C) It is lighter
• D) It is easier to mine

Q12: In the Haber process, nitrogen (N₂) is combined with hydrogen to produce:

• A) Nitrogen gas
• B) Ammonia (NH₃), used in fertilizers
• C) Nitric acid
• D) Nitrogen oxide

Q13: Which of the following nonmetals is the most reactive?

• A) Iodine (I)
• B) Bromine (Br)
• C) Chlorine (Cl)
• D) Fluorine (F)

Q14: Chlorine is used in water disinfection because:

• A) It dissolves impurities
• B) It kills bacteria and other microorganisms
• C) It increases water density
• D) It removes minerals

Q15: Argon is commonly used in welding because:

• A) It increases temperature
• B) It prevents oxidation (acts as inert atmosphere)
• C) It increases metal strength
• D) It reduces welding cost

Q16: Noble gases are chemically inert primarily because:

• A) They have no electrons
• B) They have complete valence shells (8 electrons, or 2 for He)
• C) They are heavier than other gases
• D) They react only with each other

Q17: Liquid nitrogen is useful in cryogenic applications because:

• A) It's inexpensive
• B) It's very cold (boiling point: -196°C)
• C) It's radioactive
• D) It's highly reactive

Q18: The process of coating iron with zinc to prevent rusting is called:

• A) Electroplating
• B) Galvanization
• C) Anodizing
• D) Passivation

Q19: Which ore of copper is most commonly used in extraction?

• A) Malachite (Cu₂CO₃(OH)₂)
• B) Chalcopyrite (CuFeS₂)
• C) Cuprite (Cu₂O)
• D) Chalcocite (Cu₂S)

Q20: In extracting a metal from its sulfide ore, the first step usually involves:

• A) Direct reduction with carbon
• B) Roasting in air to convert sulfide to oxide
• C) Electrolysis
• D) Displacement with another metal

Q21: Sulfuric acid is produced industrially by oxidizing:

• A) Sulfur dioxide (SO₂) to sulfur trioxide (SO₃)
• B) Sulfur to sulfur dioxide
• C) Sulfuric acid directly
• D) Hydrogen sulfide to sulfur dioxide

Q22: Which of the following statements about alloys is true?

• A) Alloys are pure metals
• B) Alloys are harder and often stronger than pure metals
• C) Alloys always have higher density than pure metals
• D) Alloys are more reactive than pure metals

Q23: The sacrificial anode method of corrosion prevention works by:

• A) Coating the metal with a protective layer
• B) Removing oxygen from the environment
• C) Attaching a more reactive metal that oxidizes instead of the protected metal
• D) Increasing the pH of water

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Answer Key: 1-C, 2-B, 3-C, 4-A, 5-C, 6-C, 7-C, 8-C, 9-B, 10-C, 11-B, 12-B, 13-D, 14-B, 15-B, 16-B, 17-B, 18-B, 19-B, 20-B, 21-A, 22-B, 23-C