1.46 understand that a metal can be described as a giant structure of positive ions surrounded by a sea of delocalised electrons

Metallic crystals

Metals have a giant, three-dimensional lattice structure in which positive ions are arranged in a regular pattern in a 'sea of electrons'.

The outer shell electrons are detached from the atoms and are delocalised throughout the structure.

The attraction between the positive ions and the delocalised electrons is known as a metallic bond and this attraction keeps the ions together.