Molecular Motion

Definition

The collective vibration, rotation, and translation of particles within a substance, which is what heat physically is. When heat moves, nothing visible travels; only energy changes hands.

Molecular motion is the energy that pushes water molecules apart and competes against intermolecular cohesion. It is expressed through three modes of movement: translation, rotation, and vibration. Adding heat speeds molecules up so they can overpower cohesion, while removing heat slows them so cohesion takes over, and this contest decides the state of water.

Related concepts

Heat Transfer · Sensible Heat · Intermolecular Cohesion

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Part of The Blueprint of Water · 🔥 thermodynamics