Uses of aluminium
2 marks · NormalDescribe what happens to the movement of the layers of atoms in aluminium when it is alloyed. Explain why this affects the strength of the metal.
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The layers cannot slide over each other as easily because atoms of different sizes disrupt the lattice. This makes the alloy stronger.
Also accept: As the metal is alloyed, the atomic layers are less able to slide, increasing strength
Common mistakes: Alloying makes layers slide more easily; Alloying makes metal weaker
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Marking points
B1 · 1 mark · States layers cannot slide over each other as easily in alloyed aluminium.
B2 · 1 mark · Explains this difficulty is due to disruption/distortion from different sized atoms, making the alloy stronger.
Worked solution
When other elements are added, the atoms disrupt the regular structure. This prevents the layers of atoms from sliding easily, so the alloy becomes stronger.