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Materials and Matter - Properties of solids, liquids, and gases

Grade 3Cambridge (IGCSE)

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Matter is everything around us that has mass and takes up space. It exists in three main states: solids, liquids, and gases.

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Solids have a fixed shape and a fixed volume. The particles in a solid are packed very closely together in a regular pattern and only vibrate in place.

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Liquids have a fixed volume but no fixed shape; they take the shape of the container they are in. The particles are close together but can move and slide past each other.

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Gases have no fixed shape and no fixed volume. They spread out to fill whatever container they are in. The particles in a gas move rapidly and are far apart.

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States of matter can change when energy (heat) is added or removed. For example, H2OH_2O can exist as ice (solid), water (liquid), or steam (gas).

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Melting is the process where a solid turns into a liquid, such as ice turning into H2OH_2O at 0∘C0^\circ C.

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Evaporation/Boiling is the process where a liquid turns into a gas, such as water turning into steam at 100∘C100^\circ C.

📐Formulae

Solid+Heat→Liquid (Melting)Solid + Heat \rightarrow Liquid \text{ (Melting)}

Liquid+Heat→Gas (Evaporation)Liquid + Heat \rightarrow Gas \text{ (Evaporation)}

Gas−Heat→Liquid (Condensation)Gas - Heat \rightarrow Liquid \text{ (Condensation)}

Liquid−Heat→Solid (Freezing)Liquid - Heat \rightarrow Solid \text{ (Freezing)}

Density=MassVolumeDensity = \frac{Mass}{Volume}

💡Examples

Problem 1:

Explain why a balloon expands when you blow air (a gas) into it.

Solution:

Gas particles move freely and spread out to fill the space available.

Explanation:

Because gas has no fixed volume or shape, the particles move rapidly in all directions, pushing against the inside walls of the balloon and causing it to inflate.

Problem 2:

What is the chemical notation for water, and what state is it in at −5∘C-5^\circ C?

Solution:

H2OH_2O in a Solid state (Ice).

Explanation:

The chemical formula for water is H2OH_2O. Since the freezing point of water is 0∘C0^\circ C, any temperature below that, like −5∘C-5^\circ C, will cause the particles to lock into a fixed solid structure.

Problem 3:

If you pour 50ml50ml of juice from a tall thin glass into a short wide bowl, what happens to the volume?

Solution:

The volume remains exactly 50ml50ml.

Explanation:

Liquids have a fixed volume, even though they change their shape to match the container they are poured into.