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How does metallic bonding hold metals together?

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Bohr model diagram of a hydrogen atom showing a green nucleus labeled H, a single electron orbit, and text with atomic mass 1.008 and electron configuration 1. — atom The Bohr model describes the structure of atoms, in this case hydrogen.

Metallic bonding holds metals together through the interaction between a lattice of positive ions and a surrounding sea of nonlocalized valence electrons.12

In this structure, the outermost electron shells of metal atoms overlap, allowing valence electrons to detach from their parent atoms and move freely throughout the entire crystal lattice. This "sea" of mobile electrons acts as a buffer, neutralizing the charges of the cations and preventing them from repelling one another, which provides the cohesive force that binds the metal together.132

The nature of this bond varies based on the electrons involved:
* Simple metals: Bonded primarily by sp-electrons, which are detached and roam freely. This results in relatively weak cohesive energy, often making these metals mechanically soft.3
* Transition metals: Involve partially filled d-shells. These electrons form stronger, more directional covalent-like bonds between neighboring atoms, contributing to the exceptional mechanical strength found in metals like iron or tungsten.3

This nonlocalized electron model also accounts for characteristic metallic properties, such as high electrical conductivity, malleability, and ductility.12