describe how adding thermal energy affects particle motion, temperature, and state.
Adding thermal energy makes particles move faster, raises the temperature, and can change the substance’s state from solid to liquid to gas as enough energy is added. When energy is removed, the opposite happens: particles slow down, temperature drops, and the state can go from gas to liquid to solid.
Particle motion
- In a solid, particles vibrate in place and are packed closely together; adding thermal energy makes these vibrations stronger and faster.
- In a liquid, particles move around one another more freely, and extra thermal energy makes them move faster and spread out more.
- In a gas, particles move very quickly and are far apart; adding thermal energy increases their speed even more, so they zoom around and occupy more space.
Temperature changes
- Temperature is a measure of the average kinetic energy (motion) of particles in a substance.
- When thermal energy is added, particle kinetic energy increases, so the temperature rises; when energy is removed, kinetic energy decreases and temperature falls.
- Even at the same temperature, some particles move slower and some faster, but adding energy shifts the overall motion toward higher speeds.
Changes of state
- Adding enough thermal energy to a solid causes melting (solid → liquid), and adding more can cause boiling/evaporation (liquid → gas), because particles gain enough energy to break many of the attractive forces between them.
- Removing thermal energy can cause condensation (gas → liquid) and freezing (liquid → solid), as particles lose energy, move less, and get pulled closer together into more ordered structures.
- In some cases, enough thermal energy can turn a solid directly into a gas (sublimation), while removing energy from a gas can turn it directly into a solid (deposition).
During phase changes
- While a substance is actually changing state (for example, melting ice at 0 °C or boiling water at 100 °C at standard pressure), added thermal energy goes into breaking or loosening particle attractions instead of raising temperature, so the temperature stays constant until the change is complete.
- This is why a mixture of ice and liquid water can sit at the same temperature even as it absorbs thermal energy, and why steam condensing releases thermal energy without its temperature changing until all of it has condensed.
Everyday examples
- Heating a pot of water on a stove adds thermal energy: water molecules move faster, the temperature rises, bubbles form, and eventually the liquid becomes water vapor.
- Leaving a cold drink out on a warm day causes thermal energy from the air to flow into the drink and the ice; ice melts (solid → liquid) because its particles gain enough energy to move out of their rigid positions.
Bottom note: Information gathered from public forums or data available on the internet and portrayed here.