IGCSE EXTENDED CHEMISTRY METALS – METALS MASTER CHEAT SHEET

Covering: Rusting, Galvanising, Blast Furnace, Reactivity Series, Group 1 Alkali Metals, Properties & Uses of Metals

🧪 1. RUSTING OF IRON (Corrosion)

🔹 Definition:

Rusting is the slow oxidation of iron in the presence of water and oxygen, producing a reddish-brown flaky substance called hydrated iron(III) oxide.

🔹 Balanced Word Equation:

Iron + Oxygen + Water → Hydrated Iron(III) Oxide

🔹 Chemical Equation:

4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃ → Fe₂O₃·xH₂O (Rust)

🔹 Conditions Required:

🔹 Ways to Prevent Rust:

🛡 2. GALVANISING METAL

🔹 Definition:

Galvanising is the process of coating iron or steel with zinc, which prevents rusting through:

1. Barrier Protection: Prevents air and water from contacting iron.

2. Sacrificial Protection: Zinc is more reactive, corrodes first.

🔹 Key Notes:

• Zinc continues to protect iron even when scratched, due to sacrificial action.

• Zinc forms Zn²⁺ ions, giving up electrons to protect Fe from oxidising.

🔥 3. BLAST FURNACE (Extraction of Iron from Hematite)

🔹 Raw Materials:

🔹 Step-by-Step Reactions:

🔹 Products:

• Iron (Fe) – collected at bottom

• Slag (CaSiO₃) – used in road construction

• Waste gases – CO₂, N₂ escape at top

⚡ 4. REACTIVITY SERIES

🔹 Definition:

The Reactivity Series ranks elements by their tendency to lose electrons and form positive ions.

🔹 Full Series with Mnemonic:

Please Stop Calling Me A Cute Zebra I Like Her Calling Smart Girls Please

🔹 Displacement Reactions:

Example:
Mg + CuSO₄ → MgSO₄ + Cu
(Magnesium displaces copper)

⚛ 5. GROUP 1 – ALKALI METALS

🔹 Characteristics:

• Soft

• Shiny when freshly cut

• Stored in oil

• Low melting/boiling points (↓ down group)

• Very reactive (↑ down group)

🔹 Reactions with Water:

Metal + Water → Metal Hydroxide + Hydrogen

Example:
2Na + 2H₂O → 2NaOH + H₂↑

🔹 Observations:

🧲 6. PROPERTIES & USES OF METALS

🔹 Alloys:

• Mixtures of metals (e.g., bronze = copper + tin)

• Harder than pure metals due to disrupted layers of atoms

📘 DEFINITIONS TO MEMORISE (Key Exam Vocabulary)

🧮 FORMULAS + MATHS IN CHEMISTRY (for high-level questions)

🔹 Moles, Mass, Mr

• Moles = Mass / Mr

• Mass = Moles × Mr

• Mr = Sum of Ar values

🔹 Volume of gas at r.t.p. (room temp and pressure)

• Volume = Moles × 24 dm³

🔹 % by Mass:

• (Ar × number of atoms / Mr of compound) × 100

🔹 Empirical Formula Steps:

1. Divide mass by Ar

2. Divide all values by smallest result

3. Use to write formula

🧠 EXAM QUIZ – QUICK A* LOCK-IN (ANSWER IN YOUR HEAD THEN CHECK)

✅ Q1: What two conditions are needed for iron to rust?

A: Oxygen and water

✅ Q2: Why does galvanising protect even when scratched?

A: Zinc is more reactive than iron and oxidises first (sacrificial protection)

✅ Q3: Give the main equation for iron extraction.

A: Fe₂O₃ + 3CO → 2Fe + 3CO₂

✅ Q4: What is slag made of?

A: Calcium silicate (CaSiO₃)

✅ Q5: Write the reaction between sodium and water.

A: 2Na + 2H₂O → 2NaOH + H₂

✅ Q6: Why do alloys have higher strength than pure metals?

A: Different atom sizes prevent layers from sliding

✅ Q7: Give 3 metals that don’t react with acid.

A: Copper, silver, gold

✅ Q8: Define oxidation and reduction.

A: Oxidation = gain of oxygen / loss of electrons; Reduction = loss of oxygen / gain of electrons

🎯 FINAL MNEMONICS RECAP

• Reactivity Series:
  "Please Stop Calling Me A Cute Zebra I Like Her Calling Smart Girls Please"

• Rusting Conditions:
  "WOW" = Water + Oxygen + iron = rust

• Blast Furnace Reactions:
  "Can Cool Friends Love Slag"
  C burns → CO → Fe extracted → Lime decomposes → Slag made

• Group 1 Trends:
  "Rats Melt Slowly" (Reactivity ↑, Melting ↓, Softness ↑)