4.5 Metallic Bonding

All metal atoms need to lose electrons.

But without any non-metal atoms they have nothing to give the electrons to.

The solution is for all metal atoms to lose electrons (and become positive ions) which are then surrounded by a “sea of delocalised electrons”.

The ions repel each other, but they are closer to the electrons so the attractions outweigh the repulsions.

2. Suggest two reasons why the melting points of Sodium, Magnesium and Aluminium vary in the way shown.

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An alloy is one metal mixed with at least one other element (often but not always another metal)

Pure metals are often rather soft and overly malleable/ductile.

This is because the atoms build up crystals in layers that slide over each other.

Alloying mixes in other atoms, either much bigger or much smaller and this disrupts the layer structure.

Steel is an alloy of Iron and Carbon.

Why is it so much stronger than Iron?

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