STATES OF MATTER

The kinetic theory of matter explains that all substances are made up of tiny particles in constant motion. These particles move faster when temperature increases and slower when it decreases. The spaces between particles and the strength of forces holding them together determine whether matter exists as a solid, liquid, or gas.

Think about how a pot of water behaves on your kitchen stove. At room temperature, water molecules move slowly and stay close together as a liquid. When you heat it, the particles move faster and faster until they escape as steam—a gas. If you freeze water, the particles barely move and form ice crystals in a fixed pattern. This transformation happens because particle movement changes with temperature, not because the water itself changes its nature.

The kinetic theory applies to everything around you: the air you breathe, the chair you sit on, and even the food you eat. Understanding this helps explain melting, boiling, evaporation, and condensation.

Matter exists in three main states: solid, liquid, and gas. Each state can change into another through the addition or removal of heat energy. When a solid is heated, it melts into a liquid. Further heating causes the liquid to evaporate and become a gas. The reverse process also occurs: a gas condenses into a liquid when cooled, and a liquid freezes into a solid as temperature drops further.

Think about how ice (solid) melts into water (liquid) when left under the hot Nigerian sun, then evaporates into water vapor (gas) as heat increases. These changes happen because heat energy affects how particles move and arrange themselves. The stronger the heat, the more freely particles move.

Understanding these transitions is crucial because examiners frequently test your ability to identify and explain state changes in practical scenarios.

Diffusion is the spontaneous spreading of particles from an area where they're concentrated to areas where they're less concentrated. Think of it as particles moving randomly until they're evenly distributed everywhere. This happens because particles are always moving due to heat energy, and they naturally spread out to fill available space.

You experience diffusion daily in Nigeria. When someone opens a bottle of perfume in your classroom, the sweet smell eventually reaches everyone sitting far away. Those perfume particles are diffusing through the air, spreading from high concentration near the bottle to lower concentration across the room.

Diffusion occurs in all three states of matter—solids, liquids, and gases. However, it happens fastest in gases because particles move freely and quickly, slower in liquids, and slowest in solids where particles are tightly packed.