States of Matter
All matter exists in three main forms: solids, liquids, and gases. The differences arise from how their particles are arranged and how they move.
Molecular Structure
- Solids — particles are closely packed and vibrate about fixed positions.
- Liquids — particles are close together but can slide over each other.
- Gases — particles are far apart and move randomly in all directions.
Distinguishing Properties
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Flow | No | Yes | Yes |
| Shape | Fixed | Takes container shape | Fills container |
| Volume | Fixed | Fixed | Can be changed |
| Density | High | High | Low |
Change of State
Matter can change from one state to another by heating or cooling.
Process Summary
- Melting: Solid → Liquid
- Boiling / Evaporation: Liquid → Gas
- Condensation: Gas → Liquid
- Freezing: Liquid → Solid
Exam Note
For the 2023–2025 examinations, sublimation (solid ↔ gas) is not required.
Key Formula
For perpendicular vectors (analogy for resultants): R = √(X² + Y²)
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