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 associated with a single atom or a covalent bond. Instead, they are delocalised, meaning they can move freely throughout the entire metal. This forms a 'sea of electrons' around the positively charged metal ions.

This 'sea of electrons' is what gives metals their unique properties. The free movement of these electrons allows metals to conduct electricity and heat efficiently. When an electric field is applied, the electrons can move freely, carrying the charge from one end of the metal to the other. Similarly, when heat is applied, the energy is quickly transferred through the movement of these electrons.

The delocalised electrons also provide a strong electrostatic attraction between the positive metal ions and the negative electron cloud. This attraction, known as metallic bonding, holds the metal atoms together in a regular structure and gives metals their characteristic strength and malleability. The electrons can move and rearrange themselves, allowing the metal to be bent or shaped without breaking.

Furthermore, the 'sea of electrons' model also explains the high melting and boiling points of metals. A lot of energy is required to overcome the strong electrostatic forces of attraction between the delocalised electrons and the positive metal ions. Therefore, metals generally have high melting and boiling points.

In summary, valence electrons in metallic bonding are not tied to specific atoms but are delocalised, forming a 'sea of electrons'. This delocalisation gives rise to the unique properties of metals, including their ability to conduct electricity and heat, their strength and malleability, and their high melting and boiling points.