Matter and Energy

Matter

Anything that has mass and occupies space.

States of Matter

The physical forms in which matter can exist: solid, liquid, and gas.

Solid

A state of matter with a definite shape and volume; particles are closely packed together.

Liquid

A state of matter with a definite volume but no definite shape; particles are close but can move past each other.

Gas

A state of matter without a definite shape or volume; particles are far apart and move freely.

Melting

The process by which a solid turns into a liquid.

Freezing

The process by which a liquid turns into a solid.

Evaporation

The process by which a liquid turns into a gas.

Condensation

The process by which a gas turns into a liquid.

Sublimation

The process by which a solid turns into a gas without passing through the liquid stage.

Deposition

The process by which a gas turns into a solid without passing through the liquid stage.

Physical Change

A change that affects one or more physical properties of a substance without changing its chemical composition.

Chemical Change

A change that occurs when one or more substances change into entirely new substances with different properties.

Boiling Point

The temperature at which a liquid turns into vapor.

Freezing Point

The temperature at which a liquid turns into a solid.

Non-Reversible Change

A change that cannot be undone, resulting in the formation of new substances.

Reversible Change

A change that can be reversed to get back the original substance.

Flammability

The ability of a substance to catch fire.

Reactivity

The tendency of a substance to undergo a chemical reaction.

Toxicity

How poisonous a substance is.

Condensation

The process by which water vapor turns back into liquid water.

Humidity

The amount of moisture in the air.

Density

The mass per unit volume of a substance.