Final answer:
In a metallic bond, mobile valence electrons form a 'sea of electrons' around positive metal ions in a crystal lattice, resulting in electrostatic attraction that constitutes the metallic bond.
Step-by-step explanation:
The electrons between atoms in metallic bonds are highly mobile and are not associated with any single atom. This characteristic leads to the formation of a 'sea of electrons' which facilitates many of the properties of metals. In a metallic bond, metals such as copper, iron, and aluminum exist in a crystal lattice structure where the metal atoms are positive ions (+ions). These ions are surrounded by a 'sea of electrons' that are free to move throughout the metal's entire 3-dimensional structure. The mobile valence electrons are also referred to as delocalized electrons. The electrostatic attraction between the positively charged atomic nuclei of metal atoms and these delocalized electrons constitutes the metallic bond. This type of bonding allows metals to conduct electricity and heat efficiently and gives them their malleability and ductility. Metals exhibit various degrees of hardness and melting points depending on the number of valence electrons contributing to the 'sea of electrons'.