Metallic Structures
"Metallic structure which is characteristic of metals in their solid or liquid states, is more complex than those considered of atomic, molecular or ionic structures. This structure contains simultaneously both neutral and ionised atoms, i.e., atoms in which some of the valency electrons have become detached. Since all the atoms of a given metal are identical, each stands the same chance of being ionised. In other words, transfer of an electron from a neutral to an ionised atom can take place without the expenditure of energy. In consequence, there is always a continuous exchange of electrons taking place in metallic structures, and they always contain a certain number of free electrons, i.e., electrons which do not belong to any particular atom at the moment.
The extremely small size of electrons enables them to travel more or less freely throughout the whole of the metal crystal. In this connection, the latter may be regarded as a space lattice of neutral atoms and positive ions in an atmosphere of an "electron gas." Since each of the structural elements of the metallic crystal is not linked preferentially with any other, the crystal as a whole is a gigantic single particle."
|
