SSC CGL - Detailed Guide 2025
Self-Paced Course
Metals and Non-Metals
Reference: NCERT Class 10, Lucent GK
1. Physical and Chemical Properties
| Property | Metals | Non-Metals |
|---|---|---|
| Appearance | Lustrous (shiny) | Dull (except iodine) |
| State | Solid (except mercury) | Solid/gas (except bromine - liquid) |
| Malleability | Malleable (can be beaten into sheets) | Non-malleable (brittle if solid) |
| Ductility | Ductile (drawn into wires) | Not ductile |
| Conductivity | Good conductor of heat and electricity | Poor conductor (except graphite) |
| Sonority | Sonorous (produce sound when struck) | Non-sonorous |
| Melting/ Boiling Point | Generally high | Generally low (except diamond) |
| Nature (Chemical) | Electropositive, form basic oxides | Electronegative, form acidic/neutral oxides |
Example:
Metals → Iron (Fe), Copper (Cu), Zinc (Zn), Aluminium (Al)
Non-Metals → Sulphur (S), Oxygen (O₂), Carbon (C), Phosphorus (P)
2. Reactivity Series
A list of metals arranged in order of their reactivity from highest to lowest:
| Reactivity Level | Metals |
|---|---|
| Highly Reactive | K > Na > Ca > Mg > Al |
| Moderately Reactive | Zn > Fe > Pb |
| Less Reactive | Cu > Hg > Ag > Au > Pt |
Key Points:
• More reactive metals displace less reactive ones from their compounds.
• Reactivity determines how metals are extracted from ores.
Order of Reactivity (Mnemonic):
K Na Ca Mg Al Zn Fe Pb (H) Cu Hg Ag Au Pt
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3. Alloys and Corrosion
Alloys
A homogeneous mixture of two or more metals or a metal with a non-metal.
Purpose: To improve hardness, strength, corrosion resistance.
| Alloy | Composition | Use |
|---|---|---|
| Bronze | Copper + Tin | Medals, statues |
| Brass | Copper + Zinc | Electrical fittings, decorative items |
| Steel | Iron + Carbon | Construction, tools |
| Stainless Steel | Iron + Chromium + Nickel | Cutlery, utensils |
| Solder | Lead + Tin | Joining electric wires |
| Duralumin | Aluminium + Copper + Magnesium | Aircraft parts |
Corrosion
Gradual destruction of metals due to reaction with air and moisture.
| Metal Affected | Name of Corrosion | Reaction Example |
|---|---|---|
| Iron | Rusting | Fe + H₂O + O₂ → Fe₂O₃·xH₂O (Rust) |
| Silver | Tarnishing | Ag + H₂S → Ag₂S (black coating) |
| Copper | Green coating | Cu + CO₂ + H₂O → CuCO₃·Cu(OH)₂ |
Prevention Methods:
• Painting, greasing, oiling
• Galvanization (zinc coating)
• Alloying (e.g., stainless steel)
• Electroplating
4. Quick Facts
- • Gold is the most malleable and ductile metal (1g can be drawn into 2km wire)
- • Mercury is the only metal liquid at room temperature
- • Graphite conducts electricity due to delocalized electrons between layers
- • Aluminium is the most abundant metal in Earth's crust (8% by weight)
- • Gallium melts in your hand (melting point 29.8°C)
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