Metals and Non-Metals
1. Introduction
All elements can be broadly classified into METALS and NON-METALS (with some METALLOIDS having properties of both).
Examples
| Metals | Non-Metals |
|---|---|
| Iron (Fe) | Oxygen (O) |
| Copper (Cu) | Carbon (C) |
| Aluminium (Al) | Sulphur (S) |
| Gold (Au) | Nitrogen (N) |
| Silver (Ag) | Chlorine (Cl) |
| Zinc (Zn) | Hydrogen (H) |
| Sodium (Na) | Phosphorus (P) |
| Magnesium (Mg) | Iodine (I) |
2. Physical Properties Comparison
| Property | Metals | Non-Metals |
|---|---|---|
| State at room temp | Solid (except Mercury — liquid) | Solid, liquid (Bromine), or gas |
| Lustre | SHINY (metallic lustre) | DULL (except Iodine) |
| Hardness | Generally HARD (except Na, K — soft) | Mostly SOFT (diamond is very hard) |
| Malleability | YES (can be beaten into sheets) | NO (brittle) |
| Ductility | YES (can be drawn into wires) | NO |
| Conductivity | GOOD conductors of heat and electricity | POOR conductors (except graphite) |
| Sonority | YES (produce ringing sound) | NO |
| Density | Generally HIGH | Generally LOW |
| Melting point | Generally HIGH | Generally LOW |
| Tensile strength | HIGH | LOW |
Exceptions to Note
- Mercury: Liquid metal.
- Iodine: Shiny non-metal (sublimes).
- Graphite: Non-metal that conducts electricity.
- Diamond: Non-metal that is extremely hard.
- Sodium and Potassium: Soft metals (can be cut with a knife).
3. Chemical Properties Comparison
Reaction with Oxygen (Forming Oxides)
| Type | Metals | Non-Metals |
|---|---|---|
| Product | BASIC oxides (or amphoteric) | ACIDIC or NEUTRAL oxides |
| Example | 2Mg + O₂ → 2MgO (basic oxide) | C + O₂ → CO₂ (acidic oxide) |
| Test | MgO turns red litmus BLUE | CO₂ turns blue litmus RED |
Reaction with Water
- Metals: Many metals react with water/steam (reactivity varies).
- Na, K react VIOLENTLY with cold water.
- Mg reacts with HOT water/steam.
- Fe reacts with steam.
- Cu, Ag, Au do NOT react with water.
- Non-metals: Generally do NOT react with water directly (except Cl₂).
Reaction with Acids
- Metals: Many metals react with dilute acids to give HYDROGEN gas.
- Zn + 2HCl → ZnCl₂ + H₂ ↑
- Mg + H₂SO₄ → MgSO₄ + H₂ ↑
- Cu, Ag, Au do NOT react with dilute acids.
- Non-metals: Generally do NOT react with dilute acids.
Displacement Reactions
A MORE REACTIVE metal can DISPLACE a LESS REACTIVE metal from its compound. Example: Fe + CuSO₄ → FeSO₄ + Cu (iron displaces copper).
4. Reactivity Series of Metals
Most Reactive → Least Reactive:
K > Na > Ca > Mg > Al > Zn > Fe > Sn > Pb > H > Cu > Ag > Au
Key Points
- K, Na, Ca: React with COLD water.
- Mg, Al, Zn: React with ACIDS readily.
- Fe, Sn, Pb: React slowly with acids.
- Cu, Ag, Au: Do NOT react with dilute acids (called NOBLE metals).
5. Uses of Metals
| Metal | Uses |
|---|---|
| Iron (Fe) | Construction (buildings, bridges), machinery, tools |
| Copper (Cu) | Electrical wires, coins, cooking utensils |
| Aluminium (Al) | Aircraft bodies, food packaging, window frames |
| Gold (Au) | Jewellery, electronic connectors, coins |
| Silver (Ag) | Jewellery, silverware, photography |
| Zinc (Zn) | Galvanising iron, dry cell batteries |
| Mercury (Hg) | Thermometers, barometers |
Uses of Non-Metals
| Non-Metal | Uses |
|---|---|
| Oxygen (O₂) | Breathing, combustion |
| Carbon (C) | Fuel (coal), diamonds, graphite in pencils |
| Nitrogen (N₂) | Fertilizers, food packaging |
| Chlorine (Cl₂) | Water purification, bleaching |
| Sulphur (S) | Matchsticks, gunpowder, vulcanisation of rubber |
| Hydrogen (H₂) | Fuel, ammonia production |
6. Alloys
An ALLOY is a HOMOGENEOUS MIXTURE of a metal with one or more other elements (usually metals).
| Alloy | Composition | Use |
|---|---|---|
| Steel | Iron + Carbon | Construction, tools |
| Stainless steel | Iron + Chromium + Nickel | Utensils, surgical instruments |
| Brass | Copper + Zinc | Musical instruments, decoration |
| Bronze | Copper + Tin | Statues, medals |
| Solder | Lead + Tin | Soldering electrical joints |
7. ICSE Exam Focus
| Topic | Marks | Frequency |
|---|---|---|
| Physical properties comparison | 3 marks | Very High |
| Chemical properties (oxides reaction) | 2-3 marks | High |
| Reactivity series | 2 marks | High |
| Uses of metals and non-metals | 2 marks | Medium |
| Alloys (composition and uses) | 2 marks | Medium |
Common Mistakes
- Saying ALL metals are hard (Na, K are soft enough to cut with a knife).
- Confusing basic and acidic oxides — metal oxides are BASIC (turn red litmus blue).
- Thinking all non-metals are gases at room temperature (C, S, P, I are solids; Br is liquid).
- Forgetting Mercury is a liquid metal.
Self-Test (5 Questions)
Q1. Which non-metal is a good conductor of electricity? (1 mark)
- A) Sulphur
- B) Iodine
- C) Graphite
- D) Phosphorus
Q2. 'Name the only metal that is liquid at room temperature.' (1 mark)
Q3. 'What type of oxide does a metal form? How can you test it?' (2 marks)
Q4. Arrange in order of reactivity: Zn, Na, Cu, Fe. (2 marks)
Q5. 'Why is stainless steel preferred for cooking utensils over ordinary steel?' (2 marks)
Answers
A1. C) Graphite (an allotrope of carbon). A2. Mercury (Hg). A3. Metals form BASIC oxides. Test: Add water to the oxide and test with red litmus — it turns BLUE. A4. Most reactive: Na > Zn > Fe > Cu (least reactive). A5. Stainless steel does NOT rust (it contains chromium which prevents rusting). It is also more durable and shiny.
