Electrons revolve in orbits around the nucleus.
The location of every electron in its orbit signifies a certain potential
energy. There is a attraction force between every electron and nucleus due to
opposite electric charge. This force is more in the electron to the nucleus
than that of farther electrons.
Since, the bond between the outer
electron and the nucleus is weaker; it is easy to detach the electron from
their parent atom.
As stated earlier, every orbit in an atom
signifies certain potential energy, the orbit are also referred as energy
level.
When numbers of atoms come closer, the
force acts on the electrons, is not only due to its parent nucleus but it is
also due to electric forces of other atoms. The effect of is more pronounced on
the outermost electrons. Due to these electric forces the energy level of the
electrons changes. Obviously, the energy level of outermost electrons suffers
the greater changes. Thus the energy level which are sharply defined in an
isolated atom, are now broadened into energy bands. Mainly two bands are
formed, one is called conduction band and other is valance band. The conduction
band is associated with the higher energy level than valance band.
The gap between these two bands is known
as band gap or forbidden energy gap. Each material has its won unique band
structure. This band structure is generally used for explaining the electrical
conductivity of a metal.
In metal, atoms are tightly packed
together. Because of that, electrons of outermost shell experience a
significant electrical force from neighbouring atoms. So the valance band and
conduction band come very close together and may even overlap. Consequently, by
receiving a small amount of energy, these electrons readily ascend to higher
levels in the conduction band and are available as electrons that can move
freely within the metal, as free electron. Whenever an electrical field is
applied, these free electrons readily move towards higher potential zone. The
movement of electron implies flow of charge within the metal piece. The
quantity of charge flows within one second is defined as electric current. This
is how metal conducts electricity.
Sign up here with your email
ConversionConversion EmoticonEmoticon