STUDENT SPACE · TOPIC 1
Compounds and ions
Distinguish mixtures from compounds and explain how ions form.
The essentials
- Compounds contain different elements chemically combined in a fixed ratio. Mixtures have variable composition and can be separated physically.
- A chemical change forms new substances. A physical change does not.
- Positive ions form when atoms lose electrons. Negative ions form when atoms gain electrons. The nucleus stays unchanged.
Key vocabulary
| English | Chinese |
|---|---|
| compound | 化合物 |
| cation | 阳离子 |
| anion | 阴离子 |
Quick practice
Why does losing an electron produce a positive ion?
Need a hint?
The proton number identifies an element.
Check your reasoning after trying
There are now more protons than electrons.
Use the matching chapter worksheet. Attempt independently, compare your reasoning with your partner, then bring unresolved questions to your teacher.