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States of Matter - Properties of Solids, Liquids, and Gases

Grade 3IB

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 primary states: solid, liquid, and gas.

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Solids: Have a definite shape and a definite volume. The particles in a solid are packed very tightly together and can only vibrate in place.

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Liquids: Have a definite volume but no definite shape. They take the shape of the container they are in. The particles are close together but can slide past one another.

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Gases: Have no definite shape and no definite volume. They expand to fill whatever container they are in. Particles in a gas move very quickly and are far apart.

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Changes of State: Matter can change from one state to another when heat energy is added or removed. For example, water exists as ice (H2O(s)H_2O(s)), liquid water (H2O(l)H_2O(l)), and water vapor (H2O(g)H_2O(g)).

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Temperature Points: Pure water freezes at 0∘C0^\circ C and boils at 100∘C100^\circ C at standard pressure.

📐Formulae

Mass+Volume=MatterMass + Volume = Matter

Solid→HeatLiquid→HeatGasSolid \xrightarrow{Heat} Liquid \xrightarrow{Heat} Gas

Gas→CoolingLiquid→CoolingSolidGas \xrightarrow{Cooling} Liquid \xrightarrow{Cooling} Solid

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

💡Examples

Problem 1:

If you have 250 ml250\text{ ml} of water in a square bottle and pour it into a round bowl, what happens to the volume and the shape?

Solution:

The volume stays exactly 250 ml250\text{ ml}, but the shape changes from a square to a round shape.

Explanation:

This is a property of liquids. Because the particles in a liquid can move around each other, they take the shape of their container, but the total amount (volume) of the liquid does not change.

Problem 2:

What happens to the molecules of H2OH_2O when ice is heated to 100∘C100^\circ C?

Solution:

The H2OH_2O molecules gain energy, move faster, and eventually turn into a gas (steam).

Explanation:

Adding heat energy causes particles to move more rapidly. At 0∘C0^\circ C, the solid ice melts into liquid. At 100∘C100^\circ C, the liquid water reaches its boiling point and turns into water vapor (H2O(g)H_2O(g)).

Problem 3:

Why can you squash (compress) a balloon filled with air, but you cannot squash a solid wooden block?

Solution:

Gases have large spaces between their particles, while solid particles are already packed tightly together.

Explanation:

In a gas, there is a lot of 'empty space' between particles, allowing them to be pushed closer together. In a solid, the particles are so close that there is no room to move them further together.