chemistry term 3 2025 science test

Physical Change

A change in which no new substance is formed, often reversible, involving changes in state or form.

Chemical Change

A change that results in the formation of a new substance, usually not reversible, involving chemical reactions.

Melting

The process of a solid turning into a liquid.

Boiling

The process of a liquid turning into a gas.

Condensation

The process of a gas turning into a liquid.

Freezing

The process of a liquid turning into a solid.

Sublimation

The process of a solid turning directly into a gas without becoming a liquid.

Deposition

The process of a gas turning directly into a solid without becoming a liquid.

Melting Point

The temperature at which a solid becomes a liquid.

Boiling Point

The temperature at which a liquid becomes a gas.

Particles in Solids

Tightly packed and vibrate in place.

Particles in Liquids

Loosely packed and slide past each other.

Particles in Gases

Spread out and move quickly in all directions.

Signs of a Chemical Change

Indicators include color change, gas production, temperature change, precipitate formation, and release of light or smell.

Exothermic

A reaction that releases heat.

Endothermic

A reaction that absorbs heat.

Reactants

The substances you start with in a chemical reaction.

Products

The new substances that are formed in a chemical reaction.

Catalyst

A substance that speeds up a reaction without being consumed.

Diffusion

The process of particles spreading out.