Metallic Bonding
Chemistry: AQA A Level, topic 1.3.4
Metals and Metallic Bonding
Metals bond in a different way to non-metals
Sea of free electrons
- In a metal, the valence electrons delocalise and can move about the entire material.
- This is referred to as a 'sea of free electrons'.
- Metallic bonding is viewed as a sea of free electrons surrounding positive ion cores.
- The positive ion cores are attracted to the free electrons.
- You can think of the free electrons as a glue, holding the positive ion cores together.
Electrical conductivity
- Metals are good electrical conductors because the free electrons can move and carry current.
- A general term for moving particles which carry current is 'charge carriers'.
Melting point
- The melting point of a metal is related to its group - a group 2 metal will donate two electrons to the sea of free electrons.
- This means that the positive ion cores carry a 2+ charge.
- The 2+ ion has a stronger attraction to the free electrons.
- This means the melting point is higher.
- For example, Na melts at 98oC, but Mg melts at 650oC!
Test yourself on Metallic Bonding
Why are metals good electrical conductors?
Which of the following are true of metals?