Metallic Bonding

Metallic bonding refers to the type of bonding found in metals. This unique bond structure gives metals their distinctive properties.
This form of bonding involves positively charged metal ions (cations) situated in a ‘sea’ of delocalised electrons.

Characteristics of Metallic Bonding

In metallic bonding, the outer electrons are removed from the metal atoms to form a ‘sea’ of delocalised electrons. These electrons move freely around the lattice of positively charged metal ions, providing an electrical connection between them.
The force of attraction between the delocalised electrons and metal ions, or the metallic bonds, keep the structure intact.
The bond strength varies depending on the charge on the ions and the size of the metal ions. The higher the charge and the smaller the size of the ion, the stronger the bond.

Metallic bonding leads to several properties common to metals, including high melting and boiling points, electrical and heat conductivity, malleability, and ductility.
High melting and boiling points: The strong attraction between the delocalised electrons and metal ions means a lot of energy is needed to overcome the bonds, leading to high melting and boiling points.
Electrical and heat conductivity: The free movement of the delocalised electrons allows metals to conduct heat and electricity very efficiently.
Malleability and ductility: The delocalised electrons allow the metal ions to slide over each other without breaking the bond, resulting in malleability (the ability to be hammered into shape) and ductility (the ability to be drawn into wires).

Metals crystallise in lattice structures. There are varying structural arrangements depending on the specific metal, these include body-centred cubic, face-centred cubic and hexagonal close-packed structures.
These structures contribute to the strength and density of the metals.

Alloys are mixtures of metals. The different sized atoms of the mixed metals distort the regular arrangements of the metal ions in the lattice, making it harder for the layers to slide over each other. This results in alloys being harder and stronger than pure metals.

This knowledge of metallic bonding and its subsequent properties is fundamental to understanding many chemical reactions and the behaviour of metals.