What is the Activity Series of a Metal in Electrochemistry?

The Activity Series of a Metal is a list that ranks metals according to their reactivity with other substances, such as acids and water. In electrochemistry, it helps predict the outcomes of reactions involving metals, such as displacement reactions. Metals higher in the series are more reactive and can displace metals lower in the series from their compounds.

How is the Activity Series of a Metal used in predicting chemical reactions?

In the IB MYP Science curriculum, the Activity Series is used to predict whether a metal can displace another metal from a compound. For example, if a metal is higher in the series than the metal in a compound, it can replace the latter in a reaction. This is crucial for understanding single displacement reactions in electrochemistry.

Why are some metals more reactive than others in the Activity Series?

The reactivity of metals in the Activity Series is determined by their ability to lose electrons and form positive ions. Metals that lose electrons easily are more reactive. Factors such as atomic structure, ionization energy, and electron affinity influence this ability, making some metals more reactive than others.

Can the Activity Series of a Metal change over time or with conditions?

The Activity Series itself is a theoretical construct and does not change over time. However, the reactivity of metals can be influenced by environmental conditions such as temperature and pressure. In practical applications, these conditions can affect the outcomes of reactions predicted by the Activity Series.

How does the Activity Series relate to the extraction of metals?

In the context of the IB MYP Science curriculum, the Activity Series is essential for understanding metal extraction processes. Metals higher in the series are more reactive and often require more energy-intensive methods for extraction, such as electrolysis. Less reactive metals can be extracted using simpler methods like reduction with carbon.

Why is "Applying displacement to mixed reactions (e.g. iron + sodium chloride)." a common mistake in Activity series of a Metal?

Why it happens: Same word. How to avoid it: Displacement applies metal-with-metal-salt (or halogen-with-halide). Iron + NaCl wouldn't work because Na is way above Fe.

Why is "Saying iron is extracted by electrolysis." a common mistake in Activity series of a Metal?

Why it happens: Electrolysis sounds modern. How to avoid it: Iron is less reactive than carbon, so carbon reduction in a blast furnace is cheaper and works. Reserve electrolysis for K, Na, Ca, Mg, Al.

Why is "Confusing H's position in the series as if it's a metal." a common mistake in Activity series of a Metal?

Why it happens: It's in the list. How to avoid it: H is included as a REFERENCE — metals above react with acids; below don't. H itself is a non-metal.

ElectrochemistryIB MYP Sciences (Years 1-5)

Activity series of a Metal

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Activity Series of Metals — IB MYP Sciences: ranking metals by reactivity and predicting displacement

Why does sodium react explosively with water but gold sit unchanged for centuries? The activity series ranks metals by their tendency to lose electrons. This MYP Sciences note covers the order, the underlying reasoning, and how to use the series to predict displacement reactions.

What you’ll learn

Mapped to the IB MYP Sciences subject guide (2026 onwards).

MYP Sciences A — State the order of the reactivity series for the common metals.
MYP Sciences A — Predict whether a displacement reaction will occur.
MYP Sciences A — Explain why some metals are found native and others need extraction.
MYP Sciences D — Link the activity series to choice of extraction method.

The activity series order

Most reactive at the top, least at the bottom.

Memorise the order for common metals (mnemonics help):

Position	Metal
Most reactive	Potassium (K)
	Sodium (Na)
	Calcium (Ca)
	Magnesium (Mg)
	Aluminium (Al)
	Zinc (Zn)
	Iron (Fe)
	(Hydrogen) — for reference
	Copper (Cu)
	Silver (Ag)
Least reactive	Gold (Au)

A common mnemonic: Please Stop Calling Me A Zebra Instead Call Some Great Advice — letters match K, Na, Ca, Mg, Al, Zn, Fe, (H), Cu, Ag, Au.

Reactivity series: most reactive metals at the top, least at the bottom. Hydrogen included as a reference.

The further UP the series, the more easily the metal loses electrons → more vigorous reactions, more tendency to corrode, more drive to form positive ions.

Top = most reactive (K, Na, Ca, ...).
Bottom = least reactive (Au, Ag, Cu).
Hydrogen sits between Fe and Cu — used as reference.

Displacement reactions

A more reactive metal kicks a less reactive one out of its compound.

A displacement reaction happens when a more reactive metal pushes a less reactive one out of its compound. Classic example:

$\text{Zn (s)} + \text{CuSO}_4 \text{ (aq)} \rightarrow \text{ZnSO}_4 \text{ (aq)} + \text{Cu (s)}$

Zinc is above copper → zinc displaces copper. The blue Cu²⁺ solution becomes colourless ZnSO₄, and brown copper metal coats the zinc.

In electron terms (redox!):

Zn → Zn²⁺ + 2e⁻ (oxidation; lost electrons).
Cu²⁺ + 2e⁻ → Cu (reduction; gained electrons).

Use the series to predict any displacement. Can iron displace gold from gold chloride? Yes (Fe is above Au). Can gold displace iron from iron sulfate? No (gold is below iron).

Reaction with water and acid:

K, Na, Ca: react VIGOROUSLY with cold water (give H₂ + alkali). Sodium fizzes; potassium ignites.
Mg: reacts slowly with cold water, faster with steam.
Al, Zn, Fe: react with steam but not really with cold water.
Cu, Ag, Au: don't react with water at all.
K, Na, Ca, Mg, Al, Zn, Fe (above H): all react with dilute HCl to give H₂.
Cu, Ag, Au (below H): don't react with dilute HCl.

More reactive metal displaces less reactive from compounds.
Above hydrogen in series → reacts with acids.
Above magnesium → reacts with cold water.

Native metals and choice of extraction

Reactivity dictates whether a metal is found pure or has to be extracted.

Metals at the BOTTOM of the series (Au, Ag, Pt) are so unreactive that they don't combine with other elements in nature — they're found native (as pure metal). This is why gold can be panned from rivers as nuggets, and ancient Egyptians could work with pure copper before they had any chemistry.

Metals further up exist as compounds (oxides, sulfides, carbonates). Getting the metal out depends on its reactivity:

Most reactive (K, Na, Ca, Mg, Al): require electrolysis — only electricity can supply enough energy to break their strong bonds.
Mid-range (Zn, Fe): extracted by reduction with carbon (carbon takes the oxygen, leaving the metal). Iron is extracted in a blast furnace this way.
Least reactive (Cu, Ag, Au): extracted by simple heating of the ore, or sometimes by displacement.

This connects directly to MYP criterion D — discuss why aluminium became economically useful only after the invention of electrolysis (Hall-Héroult process, 1886), even though it's the third most abundant element in Earth's crust.

Au, Ag often found native.
K, Na, Ca, Mg, Al → electrolysis.
Zn, Fe → reduction with carbon.
Cu, Ag → heating ore, or displacement.

How it’s examined

Criterion A tests recall of the series and prediction of displacement. Criterion D often asks for an evaluation of which extraction method is suitable for a given metal, and the historical/economic impact of the choice.

Sources: IB MYP Sciences guide (IBO, official subject guide). Last reviewed 2026-05-25.

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Step-by-step worked examples — Activity series of a Metal

Step-by-step solutions to past-paper-style questions on activity series of a metal, written exactly the way a tutor would explain them at the board.

1Will displacement happen?
Getting started• displacement
Question
Predict whether each reaction will occur: (a) Zn + CuSO₄, (b) Cu + ZnSO₄, (c) Mg + FeCl₂.
Step-by-step solution
1. Step 1
  (a) Zn above Cu → YES, Zn displaces Cu.
2. Step 2
  (b) Cu below Zn → NO.
3. Step 3
  (c) Mg above Fe → YES, Mg displaces Fe.
Answer
(a) yes, (b) no, (c) yes.
2Choosing an extraction method
Building confidence• extraction
Question
Why is aluminium extracted by electrolysis but iron extracted by carbon reduction?
Step-by-step solution
1. Step 1
  Aluminium is HIGH in the reactivity series (above carbon) — bonds in Al₂O₃ are too strong for carbon to break.
2. Step 2
  Iron is BELOW carbon — carbon can take the oxygen from iron oxide, giving pure iron.
3. Step 3
  Electrolysis uses electrical energy directly to break strong ionic bonds, so it works for the most reactive metals.
Answer
Aluminium is too reactive for carbon reduction; electrolysis supplies enough energy. Iron is less reactive than carbon, so carbon can reduce iron oxide.
3Why is gold found native?
Stretch• native metals
Question
Explain why gold can be found as nuggets in rivers, but iron is never found pure in nature.
Step-by-step solution
1. Step 1
  Gold is at the very BOTTOM of the reactivity series — it doesn't combine with O₂, H₂O or other substances.
2. Step 2
  Iron is MID-LEVEL in reactivity — it readily forms iron oxide (rust) with oxygen and water in the environment.
3. Step 3
  So gold stays pure forever in rivers; any iron exposed to the environment quickly oxidises and ends up as ore.
Answer
Gold is so unreactive it never combines with anything. Iron quickly oxidises to iron oxide, so it's only ever found as ore.

Key Definitions and Keywords — Activity series of a Metal

Definitions to memorise and the exact keywords mark schemes credit for activity series of a metal answers — sharpened from recent examiner reports for the 2026 IB MYP Sciences sitting.

Activity (reactivity) series
Examiner keyword
A list of metals in order of how readily they lose electrons (most reactive at the top).
Displacement reaction
Examiner keyword
A reaction where a more reactive metal pushes a less reactive metal out of its compound.
Native metal
A metal found in nature as the pure element rather than combined in a compound. Typical of unreactive metals (Au, Ag, Pt).

Common Mistakes and Misconceptions — Activity series of a Metal

The traps other students keep falling into on activity series of a metal questions — taken from recent IB MYP Sciences examiner reports and mark schemes — and how to avoid them.

✕Applying displacement to mixed reactions (e.g. iron + sodium chloride).
Why it happens
Same word.
How to avoid it
Displacement applies metal-with-metal-salt (or halogen-with-halide). Iron + NaCl wouldn't work because Na is way above Fe.
✕Saying iron is extracted by electrolysis.
Why it happens
Electrolysis sounds modern.
How to avoid it
Iron is less reactive than carbon, so carbon reduction in a blast furnace is cheaper and works. Reserve electrolysis for K, Na, Ca, Mg, Al.
✕Confusing H's position in the series as if it's a metal.
Why it happens
It's in the list.
How to avoid it
H is included as a REFERENCE — metals above react with acids; below don't. H itself is a non-metal.

Practice questions

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