The Reactivity Series
Order common metals in the reactivity series and explain how a more reactive metal displaces a less reactive one; describe how carbon is used to extract metals from their oxides in industry
What a learner can do afterwards
- Recalls the order of common metals in the reactivity series (potassium to gold)
- Predicts whether a displacement reaction will occur given two metals
- Explains why carbon can be used to extract iron from iron oxide but not aluminium from aluminium oxide
- Links the reactivity series to the history of metal use (gold found free, iron smelted, aluminium electrolytic)
The lesson
Chemists arrange common metals into a list called the reactivity series, ordered from the metal that reacts fastest down to the metal that barely reacts at all. Potassium sits at the top. Gold sits at the bottom, which is why gold barely reacts with anything around it.
Zinc sits above copper in the reactivity series, so zinc is more reactive. Drop a strip of zinc into a blue copper sulfate solution and the zinc pushes the copper out: a layer of copper metal builds up on the zinc, and the blue color fades. A more reactive metal always displaces a less reactive metal from its compound.
Reactivity also explains how metals get separated from their ores, the rocks that contain metal oxides. Carbon can rip oxygen away from any metal that sits below carbon in the reactivity series, so heating iron oxide with carbon leaves pure iron behind. Aluminium sits above carbon, so carbon cannot pull oxygen away from aluminium oxide. Instead, factories use electrolysis, an expensive process that passes electricity through the melted ore.
One way to remember the order: Please Send Cats Monkeys And Cute Zebras In Cars, Silly Goose, for potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, copper, silver, gold. That order matches history too: gold sits so low that people found lumps of it pure in riverbeds thousands of years ago, iron needed carbon and fire to smelt, and aluminium stayed rarer than gold until electrolysis was invented in the 1800s.
The reactivity series ranks metals from most to least reactive, and that ranking decides which metal displaces another and which ones carbon alone can pull free from their oxide.
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8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.