Here's why:
* Temperature is a measure of average kinetic energy: The hotter something is, the faster its particles are moving. Even at absolute zero (-273.15 °C or 0 Kelvin), the theoretical point where all thermal motion ceases, particles still possess a small amount of *quantum* motion.
* States of matter and motion:
* Solids: Particles vibrate in fixed positions.
* Liquids: Particles move more freely, sliding past each other.
* Gases: Particles move rapidly and randomly, colliding frequently.
* Diffusion and Brownian Motion: These phenomena demonstrate the constant motion of particles. Diffusion is the spreading out of particles, and Brownian motion is the random movement of particles suspended in a fluid.
In summary: Particles of matter are constantly in motion, even if it's just tiny vibrations. Their motion is directly related to temperature and dictates the properties of different states of matter.
