Giant Metallic Lattice

Summary: A giant metallic lattice is a regular arrangement of positive metal ions held together by the electrostatic attraction between the ions and a “sea” of delocalised electrons, explaining the conductivity and malleability of metals. Tags: igcse chemistry Created: 2026-07-18

A giant metallic lattice is the structure adopted by solid metals: a regular, repeating arrangement of positive metal ions extending in three dimensions throughout the entire piece of metal, surrounded by a “sea” of delocalised electrons. Metallic Bonding is defined (Syllabus 2.7 Supplement) as the electrostatic attraction between these positive ions and the delocalised electrons, and it is this attraction that holds the lattice together. The delocalised electrons come from the outer shell (valence) electrons of the metal atoms, which are released and become free to move throughout the whole structure rather than belonging to any one atom. Because the lattice is a single continuous giant structure rather than a collection of discrete molecules, strong bonding acts throughout the metal, giving most metals high melting and boiling points. This model directly explains two characteristic metallic properties: electrical conductivity (mobile delocalised electrons carry charge) and malleability (layers of ions can slide without breaking the bonding). It is one of the three giant structures met at IGCSE, alongside the giant ionic lattice and giant covalent structures.

Structure of the Lattice

Each metal atom contributes its outer shell electrons to the sea, so the charge on the ions matches the group number of the metal. For example, sodium forms Na⁺ ions and contributes one electron per atom, while magnesium forms Mg²⁺ ions and contributes two. The more delocalised electrons per ion and the higher the ionic charge, the stronger the attraction and the higher the melting point.

Note that although the metal contains positive ions, the metal as a whole is electrically neutral: the total negative charge of the delocalised electrons exactly balances the total positive charge of the ions.

Explaining the Properties of Metals

Electrical Conductivity

The delocalised electrons are free to move throughout the lattice. When a potential difference is applied across the metal, the electrons drift towards the positive terminal, carrying charge through the solid. This is why metals conduct electricity in both solid and liquid states — unlike ionic compounds, which conduct only when molten or dissolved (see Electrolysis), because their ions are fixed in place in the solid lattice.

The mobile electrons also transfer kinetic energy rapidly through the lattice, which is why metals are good thermal conductors.

Malleability and Ductility

Because the metallic bond is non-directional — every ion is attracted to the surrounding electron sea rather than to specific neighbours — layers of positive ions can slide over one another when a force is applied. The electron sea moves with the ions and continues to bind the structure together in its new shape, so the metal deforms without shattering. This accounts for Malleability (hammering into shape) and Ductility (drawing into wires), properties exploited in the many Uses of Metals.

High Melting and Boiling Points

The electrostatic attraction between the ions and the electron sea is strong and acts throughout the giant lattice, so a large amount of energy is needed to separate the particles. Most metals therefore have high melting and boiling points (mercury is a notable exception).

Sources

• Cambridge IGCSE Chemistry 0620 Syllabus (2023-2025) — Section 2.7 Metallic bonding, Supplement 1–2, Cambridge Assessment International Education

Common Misconceptions