How does metallic bonding hold metal atoms together?

Metallic bonding is the force that holds atoms together in a metallic substance. In this structure, metal atoms are closely packed, and their outermost valence electrons are not associated with any specific pair of atoms.1

Instead, these electrons become nonlocalized, forming a "sea" of mobile electrons that wander freely throughout the entire crystal lattice. As the atoms lose these electrons, they become positive ions. The cohesive force that binds the metal together arises from the electrostatic interaction between these positive ions and the surrounding sea of negative, mobile valence electrons.12

This bonding mechanism also accounts for the characteristic properties of metals:
* Conductivity: The mobility of the valence electrons allows them to carry electric current and transmit energy.2
* Malleability and Ductility: Because the binding force is nondirectional, the ions can easily slide past one another without fracturing the crystal, while the mobile electrons act as a buffer to prevent repulsive forces between the ions.1