Higher tier: Conduction in metals
Some of the electronSubatomic particle, with a negative charge and a negligible mass relative to protons and neutrons. in a piece of metal can leave their atoms and move about in the metal as free electrons.
The parts of the metal atoms left behind are now positively charged and are called metal ionElectrically charged particle, formed when an atom or molecule gains or loses electrons..
When the free electrons absorb heat energy, they move much faster.
As they move through the metal, free electrons crash into metal ions.
Some of the kinetic energyEnergy which an object possesses by being in motion. of the free electron is absorbed by the ions and it vibrates faster and with greater amplitude.
This process is very much faster than conduction caused by just passing vibrations from atom to atom.
Hence, conduction in metals is faster than in non-metals.
Key points
- Conduction in insulators (non-metals) is only caused by passing vibrations from atom to atom.
- Conduction in good conductors (metals) is caused by collisions between fast moving free electrons and metal ions and by passing vibrations from atom to atom.
- Conduction by collisions between fast moving free electrons is very much faster than conduction by passing vibrations from atom to atom.
- Metals are good conductors because they contain free electrons.
