Lesson focus: Metals show a wide range of reactions with water and steamWater as a gas., allowing a more discriminating reactivityHow easily a substance takes part in chemical reactions. order.
Predict metal–water products and use evidence from cold water and steam to order metal reactivity.
Build on earlier learning
Metals and oxygenMetal reactions with oxygen gave one source of reactivity evidence. Water provides a second test with different products and conditions.
Practical
Metals and water
- Place small pieces of calcium, magnesium and copper in water.
- Compare the bubbling and test the gas with a lit splint.
- Test the solution with universal indicator.
Record: Observations ranked by reactivity, with word equations.
Safety: Wear eye protection.
You will be successful when you can…
- State products with cold water.
- State products with steam.
- Order metals from matched evidence.
- Apply strict safety boundaries.
Words that carry the science
- metal hydroxide
- An ionic compound containing metal ions and hydroxide ions.
- steam
- Water in the gas state; visible mist is condensed liquid droplets.
- alkaline
- Having pH above 7 because hydroxide ions are present in solution.
- reactivity
- How readily a substance undergoes a chemical reaction under stated conditions.
- oxide
- A compound containing oxygen bonded to another element.
- control measure
- An action that removes or reduces risk during a procedure.
Distinguish reactions with cold water from reactions with steam
01Very reactive metals react with cold water
The general pattern is metal + water → metal hydroxide + hydrogen for metals such as lithium, sodium and potassium. Calcium also reacts with cold water, producing calcium hydroxide and hydrogen.
The hydroxide can make the remaining solution alkalineHaving a pH above 7, like soap or toothpaste.. Reaction vigour increases down Group 1 because the outer electron is lost more easily.
02Some metals react only with steam
Magnesium reacts very slowly with cold water but more clearly with steamWater as a gas., forming magnesium oxideA compound made when an element joins with oxygen, such as rust (iron oxide). and hydrogen: magnesium + steam → magnesium oxide + hydrogen. Zinc and iron can also react with steam under suitable hot conditions.
Copper does not react with water or steam in normal school conditions. The need for steam still counts as evidence of reaction, but conditions must be stated when comparing reactivityHow easily a substance takes part in chemical reactions..
03Reactive-metal demonstrations require strict safety control measures
School evidence for Group 1 reactions should be teacher controlled, microscale and protected by a safety screen. Potassium and sodium reactions can ignite hydrogen; larger pieces or uncontrolled disposal create serious risk.
Learners can compare supplied observations or simulations without handling highly reactive metals. Risk depends on metal identity, quantity, exposed surface and method, not just the hazard name.
Infer an order from water evidence
A reacts vigorously with cold water, B reacts only with steam, and C does not react with steam.
- Cold-water reaction provides stronger evidence of reactivity than needing steam.
- A is therefore more reactive than B.
- B reacts with steam, while C does not under the same condition.
- Order the metals A > B > C.
How to make the reasoning visible: State the conditions because reactivity evidence is always tied to the test performed.
Build a water-reactivity series
Use the observation categories rather than memorising one dramatic demonstration.
| Metal | Cold water | Steam | Hydrogen? | Placement evidence |
|---|---|---|---|---|
| Potassium | Very vigorous | Not used | Yes | Highest here |
| Calcium | Steady reaction | Not needed | Yes | Below Group 1 examples |
| Magnesium | Very slow | Clear reaction | Yes | Intermediate |
| Iron | No reaction | Reacts when hot | Yes | Below magnesium |
| Copper | No reaction | No reaction | No | Lowest here |
Why is “no visible reaction with cold water” insufficient to place iron and copper together?
Why must metal quantity be small in a Group 1 demonstration?
Check your understanding
Answer from memory, then check against the suggested answer.
What gas forms when a suitable metal reacts with water?
What solid forms when magnesium reacts with steam?
Why can the solution become alkaline?
A metal fizzes slowly in cold water and leaves an alkaline solution. Name a likely product type.
Explain why steam can reveal reactions not visible in cold water.
Exam Question Practice
Exam Question Practice
Mark points shown after marking
Calcium, magnesium and copper are tested with cold water and with steam.
Compare the reactions of the three metals with water and steam.
(4)Deduce the order of reactivity.
(1)Total for this question: 5 marks
Command word: For compareA command word: say how two or more things are similar and how they are different., pair each metal with the same test conditions before giving the overall order.