What role do valence electrons play in metallic bonding?

Valence electrons in metallic bonding are delocalised and move freely, creating a 'sea of electrons' that holds the metal atoms together.

In metallic bonding, the valence electrons, which are the outermost electrons of an atom, play a crucial role. These electrons are not attached to any particular atom in the metal but are free to move throughout the entire structure. This is often described as a 'sea of electrons'. The positively charged metal ions are embedded in this sea of delocalised electrons, creating a strong bond between them.

The free movement of these valence electrons is what gives metals their unique properties. For instance, the ability of metals to conduct electricity and heat is due to these freely moving electrons. When an electric current is applied, the electrons move and carry the charge through the metal. Similarly, when heat is applied, the energy is quickly transferred through the movement of these electrons.

Moreover, the delocalised electrons also contribute to the malleability and ductility of metals. When a force is applied to a metal, the layers of atoms can slide over each other without breaking the metallic bonds. This is because the 'sea of electrons' maintains the attraction between the positive ions, even when they move position.

In summary, valence electrons in metallic bonding are not associated with individual atoms but are delocalised. They move freely throughout the metal, creating a strong bond between the positive metal ions. This delocalisation of electrons is responsible for the unique properties of metals, such as electrical conductivity, heat conductivity, malleability, and ductility.