A few minerals, such as native gold, silver, and copper, are made entirely of metal atoms packed tightly together in an orderly way. The bonding that holds these atoms together results from each atom contributing its valence electrons to a common pool of electrons, which freely move throughout the entire metallic structure. The contribution of one or more valence electrons leaves an array of positive ions immersed in a “sea” of valence electrons, as shown in Figure.
The attraction between this “sea” of negatively charged electrons and the positive ions produces the metallic bonds that give metals their unique properties.
Metals are good conductors of electricity because the valence electrons are free to move from one atom to another. Metals are also malleable, which means they can be hammered into thin sheets, and ductile, which means they can be drawn into thin wires. By contrast, ionic and covalent solids tend to be brittle, and fracture when stress is applied. Consider the difference between dropping a metal frying pan and a ceramic plate onto a concrete floor.