Malleable – IGCSE Chemistry Definition and Key Facts

Malleability is a physical property of metals tested in the Cambridge 0620 syllabus under metallic bonding and the general properties of metals. It is closely linked to ductility — both are explained by the same structural feature.

The 0620 definition

A malleable material can be hammered or pressed into a new shape without breaking. Gold is the most malleable metal — it can be beaten into sheets just a few atoms thick (gold leaf). Aluminium is hammered into thin foil used in kitchens.

Explaining malleability using metallic bonding

In a metal:

1. Positive metal ions are arranged in regular layers
2. A “sea” of delocalised electrons surrounds the ions, holding them together
3. When a compressive force (hammering) is applied, layers of ions slide over one another
4. The delocalised electrons move with the layers, maintaining the electrostatic attraction between the electrons and the positive ions throughout
5. The metallic bond is not broken — it simply reforms in the new arrangement
6. The metal changes shape instead of shattering

This explanation earns full marks on Paper 4 when candidates mention: layers sliding, delocalised electrons, and the bond not breaking.

Malleable vs ductile

Property	Meaning	Type of force	Memory aid
Malleable	Can be hammered into shape	Compressive (pushing/hammering)	Malleable = hammered
Ductile	Can be drawn into wire	Tensile (pulling/stretching)	Ductile = drawn

Both properties result from the same mechanism — layers of ions sliding while delocalised electrons maintain bonding.

Why ionic compounds are brittle, not malleable

In a giant ionic structure, positive and negative ions alternate. If a force shifts one layer:

• Positive ions line up next to positive ions
• Negative ions line up next to negative ions
• Like charges repel strongly
• The structure cracks and shatters

This contrast between metals (malleable) and ionic compounds (brittle) is a very common comparison question.

The effect of alloying on malleability

In a pure metal, all atoms are the same size. Layers slide easily, making the metal soft and very malleable. In an alloy, atoms of different sizes are introduced:

• The different-sized atoms disrupt the regular layers
• Layers cannot slide as easily
• The alloy is harder, stronger, and less malleable than the pure metal

Example: pure gold (24 carat) is too soft and malleable for jewellery. Gold alloys (18 carat = 75% gold + 25% other metals) are harder and more practical, though less malleable.

Examples of malleability in use

Metal	Malleable application
Gold	Gold leaf, jewellery
Aluminium	Kitchen foil, drink cans
Copper	Plumbing fittings shaped by pressing
Tin	Tin foil, tin cans
Lead	Historically used for roofing sheets (now avoided due to toxicity)

Worked exam question

Explain why metals can be hammered into different shapes but sodium chloride shatters when hit with a hammer. [4]

Metals have layers of positive ions surrounded by a sea of delocalised electrons [1]. When hammered, the layers slide over each other and the delocalised electrons move with them, maintaining the metallic bond [1]. Sodium chloride has a giant ionic lattice of alternating positive and negative ions [1]. When layers are forced to move, ions of the same charge are brought next to each other and repel, causing the structure to shatter [1].

Common exam mistakes

1. Confusing malleable with ductile. Malleable = hammered into shape; ductile = drawn into wire.
2. Saying metals are malleable because they are “soft” — softness and malleability are different properties. Hard metals like steel can still be shaped by pressing.
3. Explaining malleability without mentioning delocalised electrons — the electrons are what maintain the bond as layers slide.
4. Saying ionic compounds are “not malleable because the bonds are too strong” — the issue is not bond strength but the repulsion that occurs when like-charged ions align.