Single Replacement and the Activity Series
A more reactive element displaces a less reactive one.
About this topic
In a single replacement reaction, a more reactive element displaces a less reactive one from a compound: A + BC → AC + B. The activity series ranks metals (and halogens) by reactivity: potassium, sodium, calcium, magnesium, aluminium, zinc, iron, lead, hydrogen, copper, silver, gold. A metal replaces any below it, and metals above hydrogen react with acids to release hydrogen gas.
The reaction happens because the more reactive metal loses electrons more readily, so it forms ions while the other metal ion gains electrons and comes out as the metal. For example, zinc in copper(II) sulfate solution: Zn + CuSO4 gives ZnSO4 + Cu. The blue colour fades as copper plates onto the zinc. Copper in zinc sulfate does nothing, because copper is below zinc. Halogens follow the same idea: chlorine displaces bromine and iodine from their salts.
The series explains why gold and silver are found as pure metals but iron is found as ore, why aluminium needs electrolysis to extract and why iron objects are coated with zinc (galvanising), which sacrificially corrodes first. Reactions with water range from explosive potassium to no reaction for copper.
A common misconception is that every combination reacts. If the free element is lower in the series, there is no reaction. Always check the series, and write net ionic equations to show electron transfer.
Key ideas
- Activity series ranks metals
- Zinc displaces copper
- Halogens displace halides
Quick check
Use cases: where Single Replacement and the Activity Series helps
- Homework: review the key idea behind Single Replacement and the Activity Series before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Single Replacement and the Activity Series without notes.
- Visual learning: play with the interactive lab to see how Single Replacement and the Activity Series changes when you adjust its inputs.
- Teaching a friend: explain Single Replacement and the Activity Series in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Single Replacement and the Activity Series?
A more reactive element displaces a less reactive one.
What will I learn in Single Replacement and the Activity Series?
Activity series ranks metals. Zinc displaces copper. Halogens displace halides.
Is Single Replacement and the Activity Series part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Single Replacement and the Activity Series lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Single Replacement and the Activity Series?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.