States of Matter

Everything is made up of tiny particles. The state of a material depends on the strength of the forces of attraction between its particles.

When looking at objects around us, we can see that different objects are in different states of matter. The Particle Theory Model explains the unique properties of the different states of matter.

The three states of matter are solidsliquids and gases. Let’s look at how particles are arranged in each state of matter, as well as their properties.

Solids

The diagram below represents the arrangement of particles in a solid.

Illustration of a solid state of matter contained within a rectangular vessel. The vessel holds closely packed blue spheres representing particles in a solid. The word "Solid" is written at the bottom.

As shown, the particles are very close together causing them to be arranged in a regular lattice shape. The particles are close together due to the strong forces between them.

Solids maintain a fixed shape because their particles are unable to move around freely. Under certain conditions, such as when heated, the particles can vibrate around fixed positions.

Example

A close-up photograph of four translucent ice cubes with water droplets, arranged on a reflective white surface. The cubes have a blue tint and display internal fractures and bubbles.

  • Ice cubes are in a solid state

Liquids

The diagram below represents the arrangement of particles in a liquid.

A representation of a liquid state inside a container. The container is filled with loosely arranged blue spheres, signifying liquid molecules. The word "Liquid" is written at the bottom.

In liquids, particles are arranged randomly. This is because the forces between them are weak. Having said this, some of the particles are still close together.

Liquids take the shape of their containers because they can flow.Liquid particles are constantly in random motion. Similar to solids, when heated, the particles vibrate more.

Example

A close-up of water droplets falling into a serene pool, creating concentric ripples and reflections, with a gradient blue background.

  • Water is in a liquid state

Gases

The diagram below represents the arrangement of particles in a gas.

A diagram illustrating gas molecules, depicted as scattered blue spheres, within a transparent container with the label "Gas" at the bottom.

In gases, the forces between particles are very weak, allowing them to move around freely. As you can see in the diagram above, the particles are very far apart from each other. Gases always take the shape of their containers, as they have no definite shape.

When the temperature increases, gas particles move faster.

Example

A steaming saucepan on a kitchen counter, illuminated by a warm backlight, with a spoon resting inside the pan.

  • Water vapour is in a gaseous state

Comparing the States of Matter

An illustrative diagram showing the three states of matter: a stack of ice cubes labelled 'SOLID' with a close-up view of its molecular structure, a laboratory flask emitting vapour labelled 'GAS' with a depiction of its dispersed molecular arrangement, and a beaker filled with liquid labelled 'LIQUID' showcasing its closely packed molecular formation.

Below is a table that compares the three states of matter.

StateSolidLiquidGas
Arrangement of particlesRegular arrangementRandom arrangementRandom arrangement
Movement of particlesVibrate around a fixed positionMove around each otherMoves quickly in all directions
Closeness of particlesVery close togetherClose together with no regular arrangementVery spaced out

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