Properties of Metals — Metallic Bonding | IGCSE Chemistry

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 5% of your exam marks.

stable

Rare

Stable5%

Shorter-answer topic; typically tested alongside ionic and covalent bonding comparisons.

High melting and boiling points

Most metals have high melting and boiling points
The electrostatic attraction between the positive metal ions and the delocalised electrons is strong
Breaking apart the lattice needs a large amount of energy, so the melting and boiling temperatures are high
- Group 1 metals are partial exceptions (sodium melts at about 98 °C) because the attraction is weaker when each atom only releases one electron

Electrical and thermal conductivity

Metals conduct electricity in both the solid and the liquid state
- The delocalised electrons are free to move through the lattice
- When a voltage is applied, they drift toward the positive terminal and carry the charge
Metals also conduct heat well
- The delocalised electrons gain kinetic energy at the hot end and pass it rapidly through the structure

Exam tip

Why metals conduct electricity

What comes up: "Explain why metals conduct electricity" (2 marks).

Write (two marks): (1) The electrons are delocalised (2) and can move or flow through the structure, carrying charge.

Watch out: Any mention of ions or atoms moving to carry charge scores zero for M2. The answer must name electrons specifically in the first mark point — the mark scheme requires electrons to be mentioned in M1 before M2 can be awarded.

Malleability and ductility

Metals are malleable: they can be hammered into shape
Metals are also ductile: they can be drawn into wires
Both properties follow from the same feature of the lattice
- The metal atoms/ions sit in layers
- Applying a force lets the layers slip past one another into a new arrangement
- The delocalised electrons rearrange around the shifted ions, so the metallic bonding survives the change of shape
- The metal changes shape without breaking

Exam tip

Why metals are malleable (or ductile)

What comes up: "Explain why metals are malleable" or "suggest why metals can be stretched into wires" (2 marks).

Write (two marks): (1) The metal ions/atoms are arranged in layers (2) the layers can slide over one another when a force is applied.

Watch out: The mark scheme rejects any reference to intermolecular forces, and also rejects answers that describe electrons sliding. Do not say the metallic bonds break — the bonding survives because the delocalised electrons rearrange around the shifted ions.