Metallic bonding refers to the strong attraction between closely packed positive metal ions and a ‘sea’ of delocalised electrons.

More specifically, metallic bonding is a type of chemical bonding that originates from the electrostatic attractive force between conduction electrons—often conceptualized as an electron cloud or ‘sea’ of delocalised electrons—and positively charged metal ions. This type of bonding is predominant in metallic substances and is responsible for their distinctive characteristics, such as high melting and boiling points, electrical conductivity, and malleability.

The mechanism of metallic bonding occurs when the outermost electrons of metal atoms become delocalised. This delocalisation means that these electrons are not tied to any specific atom; instead, they are free to move throughout the entire metallic structure. This results in the formation of a ‘sea’ of electrons that surrounds the positively charged metal ions. It is the attraction between these ions and the delocalised electrons that constitutes the metallic bond.

The strength of a metallic bond is influenced by the number of electrons that each atom can contribute to the delocalised electron ‘sea’ as well as the charge of the metal ions. Generally, the more electrons that are delocalised and the higher the charge of the ions, the stronger the metallic bond becomes. This explains why certain metals, like iron, exhibit higher melting and boiling points than others, such as sodium.

Additionally, the ‘sea’ of delocalised electrons enables metals to conduct electricity. Since these electrons can move freely, they are capable of carrying an electric current. This property also contributes to the malleability and ductility of metals. The layers of metal ions can slide over one another without breaking the bond because the delocalised electrons can relocate to maintain the attractive forces between the ions.