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States and properties of matter

In the study of chemistry, matter is the essential substance that makes up everything in our universe. Learn the basics of matter using this resource, including its states, properties and classification.

Physical states of matter

Matter exists in three physical states: solid, liquid and gas.

Atoms in a solid mass

Solid: The particles in a solid are packed tightly with a regular pattern. They are held in place, giving solids a fixed shape and a fixed volume.

Atoms in a liquid

Liquid: In a liquid, particles are closely packed but lack a regular pattern, allowing them to slide past one another. This gives liquids an indefinite shape that conforms to their container, while maintaining a fixed volume.

Atoms in a gas

Gas: The particles in a gas move quickly and are far apart from each other. This allows gas to take the shape of the container by filling the space. Gases have both an indefinite shape and volume.


States of matter images, by RMIT, licensed under CC BY-NC 4.0

In solids, the particles are tightly packed and arranged in a regular pattern. The particles are locked in place and have minimal movement.

In liquids, the particles are closely packed but lack a regular pattern. The particles are more free to move.

In gases, the particles move quickly and are far apart from each other. The particles are very free to move.

Properties of matter

Properties of matter can be classified into two categories depending on whether it is determined by changing the chemical identity or composition of the substance.

Physical properties

If the property can be observed/measured without changing the chemical identity of the substance, it is a physical property. Examples of physical properties include:

  • Shape – the external form of a substance
  • Colour – the appearance of a substance (its hue, saturation and lightness) due to the reflection of light
  • Odour – the smell or scent of a substance
  • Hardness – the ability of a substance to resist being scratched
  • Melting point – the temperature at which the substance changes from a solid to a liquid
  • Boiling point – the temperature at which the substance changes from a liquid to a gas or vapour
  • Physical state – whether the substance is a liquid, solid or gas.

Chemical properties

If the property can only be observed or measured by altering the chemical identity of the substance, it is a chemical property. Examples of chemical properties include:

  • Flammability – the ability of a substance to ignite or burn
  • Corrosiveness – the ability of a substance to rust after exposure to moist air for prolonged periods of time
  • Acidity – the ability of a substance to donate hydrogen ions and decrease the pH of a solution
  • Reactivity – the ability of a substance to undergo a chemical reaction.

Classification of matter

Matter can be classified in many ways. You can use the flowchart shown and answer a series of yes/no questions to classify matter.

Flowchart showing a series of yes/no questions to classify matter
Matter classification flowchart, by RMIT, licensed under CC BY-NC 4.0

Matter: Anything that has mass and occupies space

Are properties and composition constant?

Yes

Pure substance (a substance that has a uniform chemical composition throughout, e.g. water, sugar, table salt).

Can the pure substance be broken into simpler substances?

  • Yes - Chemical compound (Can be chemically broken down into constituent elements, e.g. water, sugar, table salt.)
  • No - Element (Cannot be broken down into simpler substances by chemical or physical means, e.g. hydrogen, oxygen, sulfur.)

No

Mixture (A physical combination of two or more pure substances, e.g. salt–sand mixture, seawater, concrete.)

Does the mixture have a uniform composition throughout?

  • Yes - Homogeneous mixture (One visible phase which has uniform composition throughout, e.g. coffee, air, rainwater.)
  • No - Heterogeneous mixture (Two or more visible phases which have non-uniform composition throughout, e.g. vegetable stew, meat pie, salad.)

Banksia straws and seed yandying

Mixtures can be separated if we know the properties of their components, like state of matter.

In traditional times, the Gunditjmara Peoples of southwest Victoria used honeysuckle cones (banksias) as straws to filter water from muddy pools. The solid impurities would be trapped by the spikes, letting only clean drinking water through.

Banksias, image by TerriAnneAllen via Pixabay

The Yindjibarndi Peoples of the Pilbara region in Western Australia used their understanding of density (how much mass is packed into a given volume) to separate large, less dense particles from smaller and denser ones. This process is called yandying. It involves placing a mixture in a wooden container and gently shaking it on an angle so that the smaller particles would fall out first, like gold panning. Yandying was commonly used to separate sand, dirt and ash from seeds.

Your turn – states and properties of matter

Test yourself on your understanding of the states, properties and classification of matter.

Further resources

States of matter

Explore states of matter further with this helpful resource.

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