Metallic bonding is the principal force holding together the atoms of a metal. A metallic bond results from the sharing of a variable number of electrons by a variable number of atoms.
The force that binds together the atoms of metals is called metallic bond. The properties of metals cannot be explained in terms of common types of bonds such as ionic and covalent bonds. The inadequacy of these two type of bonds for metal formation can be explained as under.
The atoms of metals are all alike therefore they cannot form ionic bonds. Moreover, ionic compounds do not conduct electricity in the solid state and ionic compounds are brittle as opposed to properties of metals.The atom of metallic elements contain only 1 to 3 valence electrons, therefore these atoms cannot form covalent bonds, with noble gas configurations as they will remain incomplete. Covalent compounds are bad conductors of electricity and are generally liquids; properties opposed to metal formations. Thus, metals have a different model of bonding.