STUDENT SPACE · TOPIC 1
Particles and evidence
Use observations to explain random particle motion and diffusion.
The essentials
- Matter consists of tiny particles: atoms, molecules or ions.
- Particles in liquids and gases move continuously and randomly.
- Diffusion is net movement from higher to lower concentration caused by random particle motion.
Key vocabulary
| English | Chinese |
|---|---|
| particle | 粒子 |
| random motion | 随机运动 |
| diffusion | 扩散 |
| atom | 原子 |
| molecule | 分子 |
| ion | 离子 |
Quick practice
A smell spreads through a room. Does this mean every smell particle moves away from the source?
Need a hint?
Distinguish the motion of an individual particle from the overall change in concentration.
Check your reasoning after trying
No. Each particle moves randomly. Overall, more particles move from the concentrated region into less concentrated regions than in the reverse direction.
For more written practice, use Lesson 1 in your worksheet. Your teacher will discuss those answers in class.
Try it: States of Matter
Select a gas. Watch a single particle: does it travel in only one direction?
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