Solid
Fixed shape and volume; particle model intro.
Solid
Solid State of Matter
What you'll learn
- Properties of solids — definite shape and volume under normal conditions.
- A simple particle model: particles in solids are closely packed and vibrate in place.
- Examples from home and school — ice, wood, steel, chalk, salt crystals.
- To connect with NCERT Looking Around 5, Chapter 7 (Experiments with Water) and states of water.
Key concepts
Level 1 — Properties of solids
Verbal: Solids keep their shape unless a force breaks or bends them; they do not flow like liquids.
Symbolic: Solid → fixed shape + fixed volume (at constant temperature).
| Property | Solid behaviour | Example |
|---|---|---|
| Shape | Definite | Cube of sugar |
| Volume | Definite | Brick size unchanged in box |
| Compressibility | Very hard to compress | Syringe with cotton plugged |
| Flow | Does not flow | Sand pile keeps shape briefly but grains slide — still solid particles |
NCERT link: Looking Around 5, Ch 7 — ice as solid water; experiments melting and freezing.
Level 2 — Particle picture and daily life
Verbal: Particles are tightly arranged — strong forces hold them in fixed positions with small vibrations.
Real-life: Chalk writes on board (solid abrasive); steel spoon conducts heat; wooden desk supports books.
| Solid | Use | Why solid works |
|---|---|---|
| Ice | Cool drinks | Holds shape in tray |
| Salt | Seasoning | Crystals dissolve in water later |
| Plastic ruler | Measuring | Rigid straight edge |
Worked example
Is sand a solid? Why does it pour?
Step 1 — Each grain of sand is a tiny solid.
Step 2 — Grains slide past each other → pile flows like a liquid bulk.
Step 3 — Still classified as solid matter (each particle fixed internally).
Answer: Yes — collection of solid particles; pouring is sliding, not liquid flow.
Compare volume of a wooden block in a small box vs large box.
Step 1 — Block size unchanged.
Step 2 — Volume = amount of space block occupies — same.
Answer: Same volume; box size irrelevant.
Common mistakes
| Mistake | Why it happens | Fix |
|---|---|---|
| Powder is not solid | Looks like it flows | Fine solid particles |
| Solids cannot change shape at all | Ignoring bending/cutting | Force can deform or break solids |
| All solids hard as rock | Soft solids exist | Rubber, wax, butter (cold) are solids |
| Ice is not matter | Confusion when melting | Ice is solid state of water |
Quick check
- List two properties of solids.
- Name three solids in your kitchen.
- Do solids have fixed volume?
- Stretch: Why can you compress a sponge slightly but not a steel block much?
Revision tip: Collect five solid objects — classify each as natural (rock, wood) or man-made (plastic, glass).
Open the Practice tab for graded questions on Solid State of Matter.
Key Takeaways (TL;DR)
- What you'll learn
- Key concepts
- Worked example
- Common mistakes
Master this topic with Drishti OS
Get unlimited mock tests, AI-powered mentorship, and complete video courses when you join.
Start Free Practice