Metallic solids are the crystalline solids formed by atoms of the same metallic element. The bonding electrons are delocalised over the space of the crystal and have freedom to move from one end to the other. All these bonding electrons of the metal atoms constitute a sea of electrons. The metal atoms in the crystal are in the form of positive ions. The positive ions are arranged to form a kernel in the sea of delocalised electrons. The force of attraction between positively charged metallic ion and negatively charged sea of delocalised electrons is called metallic bond.
Kernel of metal ions in a sea of delocalised electrons. Valence electrons from sea of of electrons are not confined to one place and not restricted to any one metal ion. If energy is supplied the valence electrons from sea of electrons move from one place to another. The presence of mobile electrons make all the metals good conductor of heat and electricity. If metal is heated at one end, then the heat is transferred to the other end by mobile electrons. On application of shearing force, the layers slide on one another and hence the structure is not factured.
Metallic bonds are stronger than ionic and covalent bonds. Hence metallic bonds are tougher than other solids. The bonding in metals helps to acquire any shape to the metallic article. The metal is always present in the form of several layers arranged over one another. The layers of the metallic ions can slide on another layer. The metals are malleable and ductile i.e. they can be hammered or rolled into thin sheets of desired thickness and can be drawn into thin wires of required size. Like metals two or more metals can be alloyed together. The mixture of metals can be fused together to form alloys, which exhibit all the properties of metals. The surfaces of all metals exhibit lustre of grey or silvery colour. Gold metals exhibits yellow lustre and copper has reddish lustre.