NDA Chemistry · Metals and Non-Metals
Reactivity Series and Reactions with Water
Metals ranked from most reactive (potassium) to least reactive (gold), and how each one behaves toward cold water, hot water and steam.
Why this matters
The highest-yield subtopic in the chapter — about 6 PYQs, recurring most years. The bank tests it three ways: order the metals by reactivity, decide which metals react with cold water versus steam, and recall the alkali-metal melting-point trend. Learn the reactivity series cold and most of these become one-line answers.
Concept 1 of 3
Metals versus non-metals — the property contrast
Intuition
Before ranking metals, fix the basic contrast. Metals lose electrons easily, so they are shiny, bendable, conduct heat and electricity, and form basic oxides. Non-metals gain or share electrons, so they are dull, brittle, poor conductors, and form acidic oxides. This electron behaviour is what the whole chapter rests on.
Definition
The defining differences:
- Metals are electropositive — they lose electrons to form positive ions (cations). They are lustrous, malleable, ductile, good conductors of heat and electricity, and usually solid at room temperature (mercury is the liquid exception).
- Non-metals are electronegative — they gain or share electrons. They are dull, brittle when solid, poor conductors (graphite is the exception), and can be solid, liquid or gas.
- Metal oxides are basic; non-metal oxides are acidic.
- A more reactive metal is a stronger reducing agent because it gives up electrons more readily.
| Property | Metals | Non-metals |
|---|---|---|
| Electron behaviour | Lose electrons (electropositive) | Gain/share electrons (electronegative) |
| Appearance | Lustrous (shiny) | Dull (except graphite, iodine) |
| Malleability | Malleable and ductile | Brittle when solid |
| Conductivity | Good conductors | Poor conductors (except graphite) |
| Nature of oxide | Basic | Acidic Metal oxide + water → base; non-metal oxide + water → acid. This is a common 'which statement is correct' test. |
Metals are electropositive and form basic oxides; non-metals are electronegative and form acidic oxides.
Practice this concept4 quick reps
Practice — Level 1 (4 reps)
Quick reps to lock in the method. Try each, then check.
- 1.Are metals electropositive or electronegative?
- 2.Is a metal oxide acidic or basic?
- 3.Name the only metal that is liquid at room temperature.
- 4.Which non-metal conducts electricity?
Oxide nature is reversed for non-metals
Metal oxides are basic and non-metal oxides are acidic. A statement claiming metal oxides are acidic, or non-metal oxides basic, is the wrong one.
Concept 2 of 3
The reactivity series — order of metals
Intuition
The reactivity series ranks metals from the one that loses electrons most eagerly (potassium) down to the one that barely reacts at all (gold). A metal higher in the series displaces any metal below it from its salt solution. The bank asks you to put four metals in decreasing order — memorise the spine of the list.
Definition
The reactivity series, most reactive first: K > Na > Ca > Mg > Al > Zn > Fe > Pb > (H) > Cu > Hg > Ag > Au
- The metals above hydrogen (K to Pb) displace hydrogen from acids; those below (Cu, Hg, Ag, Au) do not.
- A more reactive metal is a stronger reducing agent and is harder to extract from its ore.
- Decreasing-reactivity examples the bank uses: Sodium > Iron > Copper > Silver.
| Reactivity | Metals (in order) |
|---|---|
| Most reactive | Potassium (K), Sodium (Na), Calcium (Ca) |
| Moderately reactive | Magnesium (Mg), Aluminium (Al), Zinc (Zn), Iron (Fe) |
| Least reactive | Copper (Cu), Mercury (Hg), Silver (Ag), Gold (Au) |
Decreasing reactivity: K > Na > Ca > Mg > Al > Zn > Fe > Pb > Cu > Hg > Ag > Au.
Practice this conceptself-check · 4 quick reps
Try it yourself
Arrange in decreasing order of reactivity: Copper, Zinc, Iron, Magnesium.
Practice — Level 1 (4 reps)
Quick reps to lock in the method. Try each, then check.
- 1.Which is more reactive, sodium or copper?
- 2.Which is the least reactive metal in the series?
- 3.Order by decreasing reactivity: Silver, Iron, Sodium, Copper.
- 4.Which metals do NOT displace hydrogen from acids?
From the bank · past-year question
Which one of the following is the correct arrangement of metals in the decreasing order of their reactivity?
[Q108 · Apr · 2023]
Iron beats copper, copper beats silver
A common wrong ordering swaps copper and iron, or copper and silver. The correct decreasing order is Sodium > Iron > Copper > Silver — iron is above copper, copper is above silver.
Concept 3 of 3
Reactions with water and alkali-metal trends
Intuition
How violently a metal reacts with water tracks its place in the series. Potassium and sodium react with cold water and float; magnesium and iron need hot water or steam; copper does nothing. Alongside this the bank tests one physical trend — alkali-metal melting points fall as you go down the group, so caesium melts lowest.
Definition
What reacts with what:
- K, Na, Ca react with cold water, releasing hydrogen. Potassium and sodium are less dense than water and float during the reaction.
- Magnesium reacts only with hot water / steam — it does NOT react with cold water.
- Iron reacts slowly with steam, not cold water, so it does NOT liberate hydrogen from cold water.
- Copper does not react with water at all.
- Alkali-metal melting points decrease down the group (Li > Na > K > Rb > Cs), so caesium has the lowest melting point (about 28.5 °C).
- The reactivity-with-water order the bank uses: Zinc > Iron > Lead > Copper.
| Metal | Reacts with water? | Note |
|---|---|---|
| Potassium / Sodium | Yes, with cold water | Float and react vigorously (less dense than water) Both K and Na float on water; potassium reacts even more vigorously than sodium. |
| Calcium | Yes, with cold water | Reacts steadily, releasing H₂ |
| Magnesium | No (cold); yes with steam | Does NOT react with cold water |
| Iron | No (cold); slow with steam | Does NOT liberate H₂ from cold water |
| Copper | No | Below hydrogen — does not react with water |
Reactivity with water: Zinc > Iron > Lead > Copper. Caesium has the lowest alkali-metal melting point.
Practice this conceptself-check · 5 quick reps
Try it yourself
Two metals are dropped in cold water: one floats and fizzes, the other sits unreacted. Identify likely candidates.
Practice — Level 1 (5 reps)
Quick reps to lock in the method. Try each, then check.
- 1.Which metal floats in cold water while reacting?
- 2.Does magnesium react with cold water?
- 3.Which alkali metal has the lowest melting point?
- 4.Does iron liberate hydrogen from cold water?
- 5.Reactivity-with-water order of Zn, Fe, Pb, Cu?
From the bank · past-year question
Which one of the following metals floats in cold water?
[Q69 · Sep · 2022]
Magnesium and iron do NOT react with cold water
Only the most reactive metals (K, Na, Ca) react with cold water. Magnesium and iron react only with steam, so a 'reacts with cold water' claim for them is false.
Melting point falls DOWN the alkali group
Among alkali metals melting point decreases going down (Na > K > Rb > Cs), so caesium is lowest — not sodium. Bigger atoms = weaker metallic bonding = lower melting point.
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (3)
Metals versus non-metals — the property contrast5 rows
| Property | Metals | Non-metals |
|---|---|---|
| Electron behaviour | Lose electrons (electropositive) | Gain/share electrons (electronegative) |
| Appearance | Lustrous (shiny) | Dull (except graphite, iodine) |
| Malleability | Malleable and ductile | Brittle when solid |
| Conductivity | Good conductors | Poor conductors (except graphite) |
| Nature of oxide | Basic | Acidic Metal oxide + water → base; non-metal oxide + water → acid. This is a common 'which statement is correct' test. |
Metals are electropositive and form basic oxides; non-metals are electronegative and form acidic oxides.
The reactivity series — order of metals3 rows
| Reactivity | Metals (in order) |
|---|---|
| Most reactive | Potassium (K), Sodium (Na), Calcium (Ca) |
| Moderately reactive | Magnesium (Mg), Aluminium (Al), Zinc (Zn), Iron (Fe) |
| Least reactive | Copper (Cu), Mercury (Hg), Silver (Ag), Gold (Au) |
Decreasing reactivity: K > Na > Ca > Mg > Al > Zn > Fe > Pb > Cu > Hg > Ag > Au.
Reactions with water and alkali-metal trends5 rows
| Metal | Reacts with water? | Note |
|---|---|---|
| Potassium / Sodium | Yes, with cold water | Float and react vigorously (less dense than water) Both K and Na float on water; potassium reacts even more vigorously than sodium. |
| Calcium | Yes, with cold water | Reacts steadily, releasing H₂ |
| Magnesium | No (cold); yes with steam | Does NOT react with cold water |
| Iron | No (cold); slow with steam | Does NOT liberate H₂ from cold water |
| Copper | No | Below hydrogen — does not react with water |
Reactivity with water: Zinc > Iron > Lead > Copper. Caesium has the lowest alkali-metal melting point.
Watch out for (4)
- Oxide nature is reversed for non-metals→ Metals versus non-metals — the property contrast
- Iron beats copper, copper beats silver→ The reactivity series — order of metals
- Magnesium and iron do NOT react with cold water→ Reactions with water and alkali-metal trends
- Melting point falls DOWN the alkali group→ Reactions with water and alkali-metal trends
Mastery check — 4 interleaved questions
Try each one before clicking. Questions are interleaved across the concepts above, not grouped — interleaving sharpens transfer.
Which one of the following metals does NOT react with cold water?
[Q63 · Apr · 2019]
Which one of the following alkali metals has lowest melting point?
[Q106 · Apr · 2018]
Which one of the following is the correct reactivity series with water?
[Q68 · Sep · 2022]
Which one of the following metals does NOT react with cold water to liberate hydrogen gas?
[Q64 · Sep · 2023]
Drill every past-year question on this subtopic
6 questions from the bank — paginated, with cart and Word-export support.