Alloy Structure & Strength
Cambridge IGCSE Chemistry 0620 · Supplement · Metallic Bonding
🏒 The Ice Rink Problem
Imagine a hockey rink packed with perfectly identical ice cubes. Push one side — the whole surface slides smoothly. That's a pure metal: identical atoms stacked in perfect rows, layers gliding past each other with ease.
Now imagine a maintenance crew drops giant boulders and tiny pebbles randomly onto the ice. Try pushing now — the layers jam. They lock. Nothing moves. That's an alloy.
🔬 MODULE 1: Identify the Alloy
Three structures are shown below. Click the one that represents an alloy.
⚡ MODULE 2: The Shear Force Simulator
Select a material, then apply a shear force and watch what happens at the atomic level.
🔨 MODULE 3: The Hammer Test
Choose your material, then strike with the hammer.
📝 MODULE 4: Build the 3-Mark Answer
Cambridge examiners want 3 specific ideas to explain why alloys are stronger. Tap all three parts in order to assemble the perfect answer.
Your Answer:
Select the phrases above to build your answer...
⚠️ Examiner Traps — Don't Lose Marks!
"Alloy atoms are bigger so they're stronger" — Size alone earns zero marks.
Always explain the mechanism: different sizes → disrupt lattice → layers cannot slide.
"The bonds are stronger in an alloy" — Wrong! The bonds are still metallic. It's the structure that changes.
Core students: You only need to identify the alloy (different sized circles). Supplement students must explain the 3-mark mechanism.
🧠 Keyword Summary
Regular lattice
Atoms arranged in ordered repeating rows
Different sized atoms
The key ingredient of all alloys
Disrupt
To break the regular pattern
Layers cannot slide
The direct reason for hardness
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