Revision Notes: Class 8 Science Chapter 7 Particulate Nature of Matter

Class 8 Science Chapter 7: Particulate Nature of Matter — Quick Revision Notes

• Matter is made of tiny particles (atoms/molecules), each far too small to see individually, even under an ordinary microscope.
• Breaking or grinding a substance is usually a physical change — particles get smaller, but every speck remains the same substance.
• Solids: particles closely packed in fixed positions, only vibrating in place; fixed shape and fixed volume.
• Liquids: particles close together but free to move and slide past each other; fixed volume, but take the shape of their container.
• Gases: particles far apart, moving fast and randomly; no fixed shape or fixed volume.
• Interparticle attraction: strongest in solids, weaker in liquids, weakest in gases — this explains why gases mix/diffuse easily and solids do not.
• Dissolving (e.g. sugar in water): a physical process where solute particles fit into the spaces between solvent particles; this differs from a substance like sand, whose rigid particle structure doesn’t break down, so it simply settles instead.
• Sublimation: a solid changes directly into a gas (or vice versa) without passing through the liquid state — e.g. camphor, dry ice.
• If all particles were removed from an object, nothing of it — its structure, shape, or mass — would remain, since particles are what the object is made of.
• Diffusion: the spontaneous spreading of one substance’s particles through another (like a smell filling a room) — fastest in gases due to their weak interparticle forces and high particle speed.

Frequently Asked Questions

What does it mean to say that matter has a particulate nature?
It means that all matter is made up of extremely small particles that are constantly in motion, and there are tiny gaps between these particles, which explains many observable properties of solids, liquids, and gases.

Last Updated: September 23, 2026

How does the particulate nature of matter explain the process of diffusion?
Because particles of matter are always in random motion, particles of one substance can spread out and mix with particles of another substance without stirring, a process called diffusion, fastest in gases and slowest in solids.

Written by Satish

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