Particulate Nature of Matter

Overview

All matter is made of tiny particles that are constantly moving. This chapter explains the three states of matter and how the arrangement and motion of particles explain their properties.

Key concepts

• Matter is made of very small particles with spaces between them.
• Particles are always moving and attract each other.
• Solids have closely packed particles and a fixed shape.
• Liquids have particles that can move and take the shape of the container.
• Gases have particles far apart that fill all available space.

Important terms / formulae

• Diffusion: mixing of particles of two substances on their own.
• States of matter: solid, liquid, and gas.
• Intermolecular space: gaps between particles.
• Intermolecular force: attraction between particles.

Solved example or key process

When a drop of ink is added to water without stirring, the colour slowly spreads through the whole water. This is diffusion, and it shows that particles of matter are moving and that there are spaces between them.

Important questions

1. State the main points of the particulate nature of matter.
2. Compare the particle arrangement in solids, liquids, and gases.
3. What is diffusion? Give an example.
4. Why can gases be compressed easily but solids cannot?

Quick revision

Matter is made of moving particles with spaces and attractive forces between them. Solids are rigid, liquids flow, and gases spread out. Diffusion and compressibility prove the particle nature of matter.