Front

What is a phase change?

Back

A phase change is a transition of a substance from one state of matter to another, such as solid to liquid or liquid to gas, typically due to changes in temperature or pressure.

Front

What happens to molecules during a phase change when energy is added?

Back

When energy is added, molecules move faster, which can lead to a phase change, such as from solid to liquid.

Front

What happens to molecules during a phase change when energy is removed?

Back

When energy is removed, molecules move slower, which can lead to a phase change, such as from gas to liquid.

Front

Define 'solid' in terms of molecular movement.

Back

In a solid, molecules are closely packed together and vibrate in place, maintaining a fixed shape.

Front

Define 'liquid' in terms of molecular movement.

Back

In a liquid, molecules are close together but can move around each other, allowing the liquid to take the shape of its container.

Front

Define 'gas' in terms of molecular movement.

Back

In a gas, molecules are far apart and move freely, filling the entire volume of their container.

Front

What is the effect of temperature on molecular movement?

Back

As temperature increases, molecular movement increases; as temperature decreases, molecular movement decreases.

Front

What is the role of energy in phase changes?

Back

Energy is required to overcome molecular attractions during a phase change; adding energy can cause a substance to change from solid to liquid or liquid to gas.

Front

What is the difference between a physical change and a chemical change?

Back

A physical change affects the form of a substance but not its chemical composition, while a chemical change results in the formation of new substances.

Front

What is meant by 'molecular attraction'?

Back

Molecular attraction refers to the forces that hold molecules together; stronger attractions result in solids, while weaker attractions allow for liquids and gases.