What defines metallic bonding?

Metallic bonding is characterized by the electrostatic attraction between positively charged metal ions and a 'sea' of delocalised electrons that are free to move throughout the structure. In metallic bonds, metal atoms release some of their electrons, allowing them to become positively charged cations, while these electrons become delocalised over the entire metallic structure. This delocalisation contributes to several key properties of metals, such as electrical and thermal conductivity, as well as malleability and ductility.

When the delocalised electrons move, they help to hold the positive metal ions together in a lattice structure through strong electrostatic forces, which results in the cohesive integrity of the metal. The strength of this bond facilitates the solid and often crystalline structures found in metals. The other options do not accurately reflect the nature of metallic bonding; hence they focus on different bonding mechanisms or forces not relevant to metals.