Metallic bonding — AQA A-Level Chemistry
Test yourself on Metallic bonding with AQA A-Level practice questions.
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Metallic bonding explained
In a metal each atom releases its outer-shell electrons into the structure, leaving a regular lattice of positive ions in a sea of delocalised electrons that are free to move throughout the whole solid.
Read the full explanation
The bond is the electrostatic attraction between those positive ions and the delocalised electrons. Strength grows with the charge on the ion and with the number of electrons each atom releases, and falls as the ion gets larger, so magnesium with 2⁺ ions and two delocalised electrons per atom melts far above sodium. Because the electrons are mobile, metals conduct electricity in the solid state, and because the attraction is not directional, layers of ions can slide over each other, making metals malleable.
Your focus
- Explain why magnesium has a higher melting point than sodium in terms of ionic charge and delocalised electrons.
- Describe metallic bonding using the three elements of the mark scheme definition.
- Account for the malleability and electrical conductivity of a metal from its structure.
Metallic bonding exam tips
Marking Points
- one mark for a lattice of positive ions or cations
- one mark for delocalised electrons released from the outer shell
- one mark for electrostatic attraction between the positive ions and the delocalised electrons
- one mark for linking a greater ionic charge, more delocalised electrons or a smaller ion to a higher melting point
Examiner Tips
- 💡Give all three components in a definition: positive ions, delocalised electrons, electrostatic attraction.
- 💡When comparing metals, state the ionic charge and the number of delocalised electrons per atom explicitly.
- 💡Explain conductivity by mobile electrons, and malleability by layers of ions sliding.
Common Mistakes
- describing metallic bonding as attraction between atoms rather than between ions and electrons
- saying the electrons come from the nucleus instead of from the outer shell
- claiming the delocalised electrons still belong to individual atoms
- saying that covalent bonds break when a metal melts
- writing sea of electrons without naming the electrostatic attraction