Which theory describes metallic bonding as having all valence electrons shared among all atoms?

The Free Electron Theory accurately describes metallic bonding by presenting the concept that valence electrons are not bound to any specific atom but are instead delocalized and shared among all atoms in the lattice structure of a metal. This creates a "sea of electrons" that allows metals to conduct electricity and heat efficiently, as these free-moving electrons can flow freely throughout the metallic structure.

In this theory, the delocalization of electrons is what gives metals their characteristic properties, such as malleability and ductility, as well as their ability to conduct electricity. The framework of the theory simplifies the understanding of how metallic bonds work by focusing on the collective behavior of valence electrons rather than individual atom interactions.

The other theories mentioned address different aspects of bonding. The Octet Rule primarily pertains to the formation of stable electron configurations in covalent and ionic compounds rather than metallic bonds. Band Theory explains the electronic structure of solids, including metals, in terms of energy bands but does not specifically describe the sharing of all valence electrons as cohesively as the Free Electron Theory. Molecular Orbital Theory is used to describe the behavior of electrons in molecules, particularly covalent bonds, which differs significantly from the characteristics of metallic bonding.