Reactivity Series of Metals

🔥 Reactivity Series of Metals

The reactivity series is a list of metals arranged in order of decreasing chemical reactivity. It helps predict how metals react with air (oxygen), water, dilute acids, and their extraction methods, as well as displacement reactions and thermal stability of their carbonates.

📋 The Reactivity Series (from most to least reactive)

Potassium (K)
Sodium (Na)
Calcium (Ca)
Magnesium (Mg)
Aluminium (Al)
(Zinc (Zn)
Iron (Fe)
Tin (Sn)
Lead (Pb)
(Hydrogen - for comparison)
Copper (Cu)
Silver (Ag)
Gold (Au)

⚠ Note: Hydrogen is not a metal, but included to compare reactions with acids.

🔥 Reaction with Air (Oxygen)

Metals react with oxygen to form metal oxides. The more reactive the metal, the more vigorous and faster the reaction.

🧪 Examples:

• Potassium: Burns brightly, forming potassium oxide
• Magnesium: Burns with a bright white flame, forming magnesium oxide
• Iron: Reacts slowly, forms iron oxide (rust)
• Copper: Forms a black coating of copper(II) oxide on heating

💧 Reaction with Cold Water

Only very reactive metals (top of the series) react with cold water.

🧪 Examples:

• Potassium: Reacts violently with water, forming KOH + H₂
• Sodium: Reacts quickly, melts, and forms a ball on the water surface
• Calcium: Reacts slowly forming Ca(OH)₂ + H₂
• Magnesium and below: No reaction with cold water

💦 Reaction with Steam (Hot Water Vapor)

Metals that don’t react with cold water may react with steam.

🧪 Examples:

• Magnesium: Reacts with steam to form MgO + H₂
• Zinc: Reacts slowly with steam
• Iron: Reacts slowly, forms Fe₃O₄ (black oxide)

⚗ Reaction with Dilute Acids (e.g., HCl, H₂SO₄)

Metals above hydrogen in the reactivity series will displace H₂ gas from acids.

🧪 Examples:

• Zinc + HCl → ZnCl₂ + H₂
• Iron + H₂SO₄ → FeSO₄ + H₂
• Copper: No reaction (below hydrogen)

🧲 Displacement Reactions

A more reactive metal can displace a less reactive metal from its salt solution.

🧪 Examples:

• Zn + CuSO₄ → ZnSO₄ + Cu (Zinc displaces Copper)
• Fe + CuSO₄ → FeSO₄ + Cu

🔁 No displacement if the metal is less reactive than the one in the solution.

🧱 Extraction of Metals from their Oxides

• Very reactive metals (K, Na, Ca, Mg, Al): Extracted using electrolysis.
• Medium reactivity metals (Zn, Fe, Pb): Extracted by reduction with carbon (e.g., in a blast furnace).
• Low reactivity metals (Cu, Ag, Au): Often found native (uncombined) or extracted by heating alone.

🧪 Examples:

• Aluminium: Electrolysis of molten Al₂O₃
• Iron: Reduction of iron oxide in the blast furnace with carbon (coke)
• Copper: Roasting copper sulfide to form CuO, then reduction

🔥 Thermal Stability of Metal Carbonates

Less reactive metals form less stable carbonates, which decompose easily on heating.

🔁 General Reaction:

Metal Carbonate → Metal Oxide + CO₂

🧪 Examples:

• Copper(II) carbonate → Copper(II) oxide + CO₂ (easily decomposes)
• Zinc carbonate → Zinc oxide + CO₂ (needs stronger heat)
• Calcium carbonate: Very stable, decomposes at high temperatures

The higher the metal in the reactivity series, the more stable its carbonate.

✅ Summary Table

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