Properties of Metals Notes

Oxford AQA IGCSE Chemistry: Revision notes

Key facts

  • Metals are good conductors of heat and electricity.
  • They are malleable and ductile.
  • They usually have high melting points, high density, and are lustrous and sonorous.
  • Conduction is explained by delocalised electrons.
  • Bending is explained by layers of ions sliding while electrons keep the structure bonded.

Shared properties

Most metals conduct, can be shaped, are shiny and have high melting points.

Metals are good conductors, malleable (hammered into shape), ductile (drawn into wires), lustrous when polished, dense and sonorous. Most have high melting and boiling points; mercury is an exception.

02004006008001000120014001600MercurySodiumAluminiumCopperIronMetalMelting point (°C)
Melting points of some metals: most are high, but mercury is liquid at room temperature.

Conduct

  • Heat
  • Electricity

Shaping

  • Malleable
  • Ductile

Look and sound

  • Lustrous
  • Sonorous

Strength

  • High melting point
  • High density

Which describes a metal that can be drawn into wire?

Conduction

Delocalised electrons are free to move through the structure, carrying charge and energy.

Metals are giant structures of positive ions in a sea of delocalised electrons. When a voltage is applied, these electrons carry electrical charge. They also transfer kinetic energy quickly, and the closely packed ions pass energy on by vibrating.

Metal wire
A metal wire in a circuit: its delocalised electrons carry the current, so the lamp lights.

Electricity

  • Delocalised electrons carry charge

Heat

  • Electrons and vibrating ions transfer energy

Why do metals conduct electricity?

Bending and shaping

Layers of ions slide over each other while the delocalised electrons keep holding the structure together.

Metallic bonding is non-directional: each positive ion is attracted to the sea of electrons, not one particular neighbour. The layers move into new positions without the structure breaking.

  1. 1

    Regular layers

    Ions arranged in layers

  2. 2

    Non-directional bonding

    Attraction to the electron sea

  3. 3

    Force applied

    Layers slide

  4. 4

    Structure holds

    Metal changes shape

Why metals bend instead of shattering

Why do metals bend rather than shatter?

Metallic bonding explains it

Strong electrostatic attraction between ions and delocalised electrons explains conduction, bending and high melting points.

Metallic bonding is the strong attraction between positive metal ions and delocalised electrons, acting in all directions through the lattice.

+++++++++e⁻e⁻e⁻e⁻
Metallic bonding: positive ions (+) attracted to delocalised electrons (e⁻) in all directions through the lattice.

Conducts electricity

  • Electrons carry charge

Conducts heat

  • Electrons and ions transfer energy

Malleable and ductile

  • Layers slide

High melting point

  • Strong attraction needs lots of energy

Why do most metals have high melting points?

Try an exam question

Explain why metals are good conductors of electricity and can be bent into shape.

[4 marks]

That's the notes covered.

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