STUDENT SPACE · TOPIC 3
Explaining changes with particles
Explain properties and state changes using particles, and interpret a heating curve.
The essentials
- Solid particles vibrate about fixed positions. Liquid particles remain close but move past one another. Gas particles are far apart and move rapidly and randomly.
- Raising temperature increases the average kinetic energy of particles.
- During melting or boiling of a pure substance at constant pressure, temperature stays constant while energy is used to overcome attractions.
Key vocabulary
| English | Chinese |
|---|---|
| arrangement | 排列 |
| separation | 间距 |
| vibration | 振动 |
| kinetic energy | 动能 |
| heating curve | 升温曲线 |
| attraction | 吸引力 |
Quick practice
A pure solid is melting while being heated. Why can its temperature stay constant?
Need a hint?
Is the added energy increasing particle speed or overcoming attractions?
Check your reasoning after trying
The energy is used to overcome attractions between particles during the change of state, rather than increasing their average kinetic energy.
For more written practice, use Lesson 3 in your worksheet. Your teacher will discuss those answers in class.
Try it: States of Matter
Heat a solid in the simulation. Observe how particle arrangement and movement change. Use the simulation qualitatively, rather than as a precise heating curve.
Open simulation in a new tab ↗