Electrical Engineering ⇒ Topic : Free Electrons
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Seema
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Free Electrons We know that electrons move around the nucleus of an atom in different orbits. The electrons in the inner orbits (i.e., orbits close to the nucleus) are tightly bound to the nucleus. As we move away from the nucleus, this binding goes on decreasing so that electrons in the last orbit (called valence electrons) are quite loosely bound to the nucleus. In certain substances, especially metals(e.g. copper, aluminium etc.), the valence electrons are so weakly attached to their nuclei that they can be easily removed or detached. Such electrons are called free electrons. Those valence electrons which are very loosely attached to the nucleus of an atom are called free electrons. The free electrons move at random from one atom to another in the material. Infact, they are so loosely attached that they do not know the atom to which they belong. It may be noted here that all valence electrons in a metal are not free electrons. It has been found that one atom of a metal can provide at the most one free electron. Since a small piece of metal has billions of atoms, one can expect a very large number of free electrons in metals. For instance, one cubic centimetre of copper has about 8.5 x 10-22 free electrons at room temperature. | |
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