Metals as Conductors

Section 1 of 6Metallic bonding

Giant structure

• Giant structure Metals are giant structures in which atoms are arranged in regular layers.
• Each atom gives up its outer-shell electrons and becomes a positively charged metal ion.

Delocalised electrons

• Delocalised electrons The outer electrons no longer belong to a particular atom.
  • They move freely through the structure and are said to be delocalised.

The bond itself

• The bond itself The metallic bond is the strong electrostatic attraction between the positive metal ions and the delocalised electrons.
• This type of bonding is found in pure metals and in alloys.

Section 2 of 6Why metals conduct electricity

1Voltage applied

• Voltage applied A potential difference is connected across the metal.

2Electrons drift

• Electrons drift The delocalised electrons are free to move through the lattice towards the positive end.

3Charge carried

• Charge carried Electrons are charged, so their movement is an electric current.

4Conducts in solid and liquid

• Conducts in solid and liquid The electrons remain free in both the solid and the molten state, so metals conduct in both.

Section 3 of 6Why metals conduct heat

1

Heating one part of a metal gives the electrons there more kinetic energy.

2

The delocalised electrons move rapidly through the structure.

3

They collide with ions and other electrons and transfer energy to cooler regions.

4

Thermal energy therefore spreads quickly through the metal, much faster than in an insulator.

5

Different metals conduct heat differently: silver and copper are among the best, while steel and lead are poorer.

Section 4 of 6Linking structure to properties

Property	Reason
Electrical conductivity	Delocalised electrons carry charge through the structure
Thermal conductivity	Delocalised electrons transfer energy
High melting point	Strong attraction between ions and delocalised electrons takes a lot of energy to overcome
Malleable and ductile	Layers of ions can slide over each other without breaking the bond

Section 5 of 6Key terms

Term	Meaning
Metallic bond	The attraction between positive metal ions and delocalised electrons.
Delocalised electrons	Outer electrons that are not tied to one atom and can move through the structure.
Metal ion	A positively charged particle formed when a metal atom loses outer electrons.
Giant structure	A very large regular arrangement of atoms or ions.
Thermal conductivity	How well a material transfers heat energy.

Section 6 of 6Exam technique

1

Saying metal atoms are neutral in the lattice. They are positive ions surrounded by delocalised electrons.

2

Writing that electrons move 'throughout' the structure. Say they move through the structure.

3

Stating that the ions carry the current in a metal. In metals it is the delocalised electrons.

4

Describing delocalised electrons as being shared between two atoms, which is covalent bonding.

5

Forgetting that metals conduct in both solid and liquid states.