AQA GCSE Combined Science (8464), Higher tier · Chemistry › Chemical changes › Reactivity of metals
Practise The reactivity series. 11 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
How metals are ranked by how readily they react, how this links to forming positive ions, and how a more reactive metal displaces a less reactive one. Questions often give observations from an experiment and ask you to put metals in order or predict whether a reaction happens.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
Recall the order of the reactivity seriesPotassium, sodium, lithium, calcium, magnesium, (carbon), zinc, iron, (hydrogen), copper, from most to least reactive.
4
Describe metal reactions with water and acidSay what you would see, e.g. fizzing, and name the products (metal hydroxide or salt, plus hydrogen).
5
Deduce an order of reactivity from resultsThe more vigorous the reaction (more bubbles, bigger temperature rise), the more reactive the metal.
5
Predict whether a displacement reaction happensA metal displaces another metal from its compound only if it is more reactive.
6
Write equations for displacement reactionsFor example, zinc + copper sulfate → zinc sulfate + copper.
7
Link reactivity to forming positive ionsThe more easily a metal's atoms lose electrons to form positive ions, the more reactive the metal is.
Notes
The reactivity series
Metals can be put in order of reactivity. The order you need, most reactive first: potassium, sodium, lithium, calcium, magnesium, zinc, iron, copper.
The non-metals carbon and hydrogen are often included: carbon goes between magnesium and zinc, and hydrogen goes between iron and copper.
When metals react, their atoms lose electrons and form positive ions. The more easily a metal forms its positive ion, the more reactive it is.
Reactions with water and dilute acids
Potassium, sodium and lithium react with cold water, fizzing and moving about on the surface: metal + water → metal hydroxide + hydrogen. Potassium reacts so violently that the hydrogen catches fire with a lilac flame.
Calcium reacts steadily with cold water. Magnesium reacts only very slowly with cold water. Zinc, iron and copper show no visible reaction with cold water.
With dilute acids: metal + acid → salt + hydrogen. Magnesium fizzes quickly, zinc steadily and iron slowly. Copper does not react with dilute hydrochloric or sulfuric acid.
Calcium reacts very vigorously with dilute acids. Potassium, sodium and lithium react dangerously fast with acids, so these reactions are not done in school.
Test for hydrogen: a lit splint gives a squeaky pop.
Displacement reactions
A more reactive metal displaces a less reactive metal from its compound, e.g. from a solution of its salt.
Example: magnesium + copper sulfate → magnesium sulfate + copper. The blue colour fades, a pink-brown coating of copper forms and the mixture gets warmer.
If the metal added is less reactive, nothing happens, e.g. copper + zinc sulfate: no reaction.
You can find an order of reactivity by adding each metal to solutions of the other metals' salts and seeing which ones react.
Why some metals are more reactive grade 7+
Reactivity depends on how easily a metal atom loses its outer electrons. Potassium loses its outer electron very easily, so it reacts vigorously; copper does not form ions easily, so it is unreactive. grade 7+
In a displacement reaction, atoms of the more reactive metal lose electrons and become ions, while ions of the less reactive metal gain electrons and become atoms. grade 7+
Cheatsheet
K > Na > Li > Ca > Mg > C > Zn > Fe > H > Cu
metal + water → metal hydroxide + hydrogen
metal + acid → salt + hydrogen
A more reactive metal displaces a less reactive metal from its compound
Reactivity = tendency of a metal to form its positive ion
Copper does not react with water or with dilute hydrochloric or sulfuric acid
Hydrogen test: lit splint → squeaky pop
How to answer each type of question
Put metals in order of reactivity from results
1 to 3 marks4
Find the measure of how vigorous each reaction was: bubbles, time to disappear, temperature rise.
More vigorous means more reactive.
Write the order in the direction the question asks (most or least reactive first).
Example. A student added equal-sized pieces of four metals, W, X, Y and Z, to dilute hydrochloric acid. W: steady fizzing. X: no bubbles. Y: very rapid fizzing. Z: a few slow bubbles. (a) Put the metals in order of reactivity, most reactive first. (b) Which metal could be copper? Give a reason.
Show the model answer
(a) Y, W, Z, X (1) (b) X (1) because copper does not react with dilute hydrochloric acid / copper is less reactive than hydrogen (1)
Describe the reaction of a metal with water
2 to 3 marks4
Give what you would see: fizzing, floating, moving, melting, getting smaller.
Name both products: the metal hydroxide and hydrogen.
Example. A small piece of sodium is added to a trough of water. Describe what you would see and name the products.
Show the model answer
Fizzing / bubbles (1) Floats and moves around / melts into a ball / gets smaller and disappears (1) Products: sodium hydroxide and hydrogen (1)
Predict and explain a displacement reaction
2 to 4 marks5
Find both metals in the reactivity series.
If the solid metal is more reactive than the metal in the compound, it displaces it.
Name the products; if it is less reactive, say 'no reaction' and give the reason.
Example. A piece of zinc is placed in blue copper sulfate solution. (a) Explain why a reaction happens. (b) Write a word equation for the reaction. (c) Predict what happens when copper is placed in zinc sulfate solution.
Show the model answer
(a) Zinc is more reactive than copper (1) so zinc displaces copper from copper sulfate (1) (b) zinc + copper sulfate → zinc sulfate + copper (1) (c) No reaction, because copper is less reactive than zinc (1)
Explain reactivity in terms of ions
2 marks7
Say that metal atoms lose electrons to form positive ions when they react.
Say that the more reactive metal forms positive ions more easily.
Example. Potassium reacts much more vigorously with water than magnesium does. Explain why, in terms of ions.
Show the model answer
When metals react, their atoms lose (outer) electrons to form positive ions (1) Potassium atoms form positive ions more easily than magnesium atoms (1)
Shortcuts and memory tricks
Mnemonic for the order: Please Send Lions, Cats, Monkeys, Cute Zebras In Hot Countries (K, Na, Li, Ca, Mg, C, Zn, Fe, H, Cu).
Reactivity increases down Group 1, so potassium > sodium > lithium.
Displacement: the more reactive metal 'steals' the other metal's partner in the compound.
Anything below hydrogen (copper here) does not give hydrogen with dilute acids.
Where marks are lost
Putting lithium above sodium or potassium.
Saying copper reacts with dilute acid to give hydrogen.
Giving the metal oxide as the product with cold water: it is the metal hydroxide.
Writing 'hydrogen is produced' when asked what you would see: say 'fizzing' or 'bubbles'.
Predicting a displacement when the metal added is less reactive than the metal in the compound.
Exam technique
'Describe what you would see' means observations: bubbles, the metal disappearing, colour changes, getting warm.
When you deduce an order, quote the evidence, e.g. 'Y gave the most bubbles'.
For a fair comparison, keep the size of metal pieces, the acid concentration and volume, and the temperature the same.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Zinc reacts with dilute hydrochloric acid, but copper does not. Name the gas produced when zinc reacts with the acid.
hydrogen
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy3 marks
The reactivity series lists metals in order of reactivity.
(a) Which list shows these metals in order of decreasing reactivity (most reactive first)? Tick (✓) one box.[1]
potassium, zinc, iron, copper
copper, iron, zinc, potassium
zinc, potassium, copper, iron
iron, copper, potassium, zinc
(b) Zinc reacts with dilute hydrochloric acid, but copper does not. Name the gas produced when zinc reacts with the acid.[1]
(c) Explain, in terms of the ions that metals form, why zinc is more reactive than copper.[1]
Show the answer and mark scheme
(a)Answer: potassium, zinc, iron, copper
(b)Answer: hydrogen
hydrogen
(c)
zinc has a greater tendency than copper to form positive ions (to lose electrons)
Question 2Medium6 marks
When metals react with other substances the metal atoms form positive ions.
(a) Which metal forms positive ions most easily? Tick (✓) one box.[1]
Calcium
Copper
Iron
Zinc
(b) Explain why potassium is more reactive than magnesium. Use ideas about ions in your answer.[2]
(c) Describe what you would see when a small piece of calcium is added to cold water.[2]
(d) Hydrogen is often included in the reactivity series. Copper does not react with dilute acids. Should hydrogen be placed above or below copper in the reactivity series? Give a reason.[1]
Show the answer and mark scheme
(a)Answer: Calcium
(b)
potassium atoms lose electrons / form positive ions more easily than magnesium atoms
so potassium reacts more vigorously / faster (with water and acids)
(c)
fizzing / bubbles of gas
the calcium gets smaller / disappears
the solution turns cloudy / milky
(d)
above copper, because copper does not displace hydrogen from acids
Question 3Hard8 marks
A student wants to put four metals in order of reactivity: copper, iron, magnesium and zinc. The student has powdered samples of the metals, copper(II) sulfate solution and normal laboratory apparatus.
(a) Describe a method the student could use to put the metals in order of reactivity by measuring temperature changes. Include how the student should make it a fair test and how the results would show the order of reactivity.[6]
(b) Explain why the student should use powdered metals rather than lumps of metal.[2]
Show the answer and mark scheme
(a)
measure a fixed volume (e.g. 25 cm3) of copper(II) sulfate solution into a polystyrene cup (with a lid) using a measuring cylinder
measure the starting temperature of the solution with a thermometer
add a fixed mass (e.g. 1.0 g) of one metal powder (an excess) and stir
record the highest temperature reached and calculate the temperature rise
repeat with each metal using fresh copper(II) sulfate solution of the same concentration and volume, and the same particle size of metal
repeat each test and calculate a mean temperature rise
the greater the temperature rise, the more reactive the metal
copper produces no temperature change (no reaction), so it is the least reactive
Marked with levels of response: the full level descriptors are in the app.
(b)
powder has a larger surface area so reacts faster
so less energy is lost to the surroundings before the maximum temperature is reached / the reaction is complete