key term - Gases

Definition

Gases are one of the four fundamental states of matter. They have neither a defined shape nor volume, and they expand to fill any space available to them.

Related terms

Molecules:

These are two or more atoms bonded together. In gases, these molecules move freely and independently.

Pressure:

This is the force exerted by gas per unit area on its container's walls. It's like how much those hyperactive kids push against the playground boundaries.

Volume:

The amount of space that a substance or object occupies. For our playful kids (gases), this would be the entire playground they're running around in.