Video Transcript
In which state of matter do molecules have the greatest amount of motion? (A) Gas, (B) liquid, (C) solid.
All molecules regardless of their state of matter are in constant motion, but the amount of motion is dependent on the state. In a solid, there are strong forces between the particles that keep the particles tightly packed together. Because of the tightly packed nature of solid particles, the particles essentially stay in one spot as they vibrate and rotate.
In a liquid, there are strong forces between the particles, but these forces tend to be weaker than the forces between the particles in a solid. As the forces aren’t quite as strong, the particles in a liquid are less tightly packed and move about more rapidly than the particles in a solid.
There are weak forces between the particles in a gas. The particles in a gas are well separated from one another and move much more rapidly than the particles in a liquid or solid.
So, as a substance changes from a solid to a liquid to a gas, the forces of attraction between the particles decrease, the space between the particles increases, and the amount of motion increases. Therefore, the state of matter in which molecules have the greatest amount of motion is a gas, answer choice (A).
