The activity series of metals is a ranked list that shows which metals react most easily. Metals near the top, such as lithium and potassium, lose electrons readily and are very reactive. Metals near the bottom, such as copper, silver, and gold, are much less reactive.
This chart matters because it lets you predict whether many single-replacement reactions will happen before doing an experiment.
Key Facts
- A metal higher in the activity series can replace a metal lower in the series from a compound.
- General single-replacement pattern: A + BC -> AC + B, if A is more reactive than B.
- Metals above hydrogen can react with acids to produce hydrogen gas: metal + acid -> salt + H2.
- Very active metals such as Li, K, Na, Ca, and Ba can react with water to form a metal hydroxide and H2.
- Less active metals such as Cu, Ag, Pt, and Au do not usually replace hydrogen from acids.
- Reactivity is linked to oxidation: more active metals lose electrons more easily, M -> M^n+ + ne-.
Vocabulary
- Activity series
- A ranked list of metals arranged from most reactive to least reactive.
- Single-replacement reaction
- A reaction in which one element replaces another element in a compound.
- Reactivity
- The tendency of a substance to undergo a chemical reaction.
- Oxidation
- The loss of electrons by an atom or ion during a chemical reaction.
- Hydrogen gas test
- A test in which a burning splint makes a pop sound if H2 gas is present.
Common Mistakes to Avoid
- Putting the metals in alphabetical order is wrong because the activity series is based on chemical reactivity, not names or symbols.
- Predicting that any metal can replace any other metal is wrong because replacement only occurs when the free metal is higher in the activity series than the metal ion in the compound.
- Forgetting hydrogen in the series is wrong because hydrogen is used to predict whether a metal reacts with acid to release H2 gas.
- Assuming all metals react strongly with water is wrong because only the most active metals react readily with cold water, while many metals react slowly or not at all.
Practice Questions
- 1 Magnesium is above copper in the activity series. Will Mg + CuSO4 -> MgSO4 + Cu occur? Explain your answer and identify the metal that is replaced.
- 2 Zinc is above hydrogen, but copper is below hydrogen. If 2 samples are placed separately in hydrochloric acid, which sample produces H2 gas? Write the expected reaction for zinc with HCl.
- 3 A student places a strip of silver metal into a solution of copper(II) nitrate and observes no reaction. Explain how the activity series supports this observation.