Particles of Matter

Key points

• Matter is not continuous: it is made of very tiny particles.
• The particles are far too small to see, even with an ordinary microscope.
• KMnO₄ activity: the colour stays visible after many dilutions.
• A few crystals contain a huge number of particles.

The potassium permanganate activity (NCERT)

• Dissolve 2–3 crystals of potassium permanganate in about 100 mL of water: deep purple.
• Take 10 mL of it into 90 mL of clear water.
• Take 10 mL of the new solution into another 90 mL of water.
• Repeat 5–8 times: the water is still coloured.

What it shows

A few crystals contain a very large number of very small particles, which keep spreading out into every glass. So matter is made of particles, and they are extremely small.

• Sugar dissolves and the water level hardly rises: its particles fit into the spaces between water particles.
• A few drops of Dettol or ink spread their smell or colour through a whole glass.

Common mistakes: the colour disappears on dilution (it gets lighter but stays visible); particles are dust-sized (they are far smaller).

Quick quiz

4 questions. Choose an answer for each, then submit to see your score and the explanations.