Metallic structure and bonding

In metals, the electrons leave the outer shells of metal atoms, forming positive metal ions and a ‘sea’ of delocalised electrons. The structure of a solid metal consists of closely packed metal ions, arranged in a regular way to form a metallic lattice structure.

Delocalised electrons moving freely among an array of tightly packed metal atoms.A model for the structure of metals
Metallic bonding is the strong electrostatic force of attraction between the metal ions and the delocalised electrons.

Chemical formulae

Metallic lattices do not contain fixed numbers of atoms. This means that the chemical formula used for a metal is simply the symbol for the element. For example, the formula for iron is Fe, even though a piece of iron contains very many iron atoms.