What is the Valence electron?
The electrons in the outermost orbit are known as valence electron.
The outermost orbit has a maximum 8 number of electrons. From valence electrons, you can determine the physical and chemical properties of a material. These electrons determine whether or not the material is a chemically active; metal or non-metal or a gas or solid.
on the basis of the electric conductivity materials are generally classified into the conductors, insulators, and semiconductors. You can determine the electrical behavior of a material from the number of valence electrons.
When the number of valence electrons is less than 4 the material is usually a metal and a conductor. Examples are sodium, magnesium, and aluminum which have 1,2,3 valence electron respectively.
When the number of valence electrons is more than 4 the material is usually a nonmetal or insulator. Examples are nitrogen, sulfur, and neon which have 5,6 and 8 valence electrons respectively.
When the number of valence electrons is 4 the material has both metal and nonmetal properties which are usually a semiconductor. Examples are carbon, silicon, and germanium.
What are the free electrons?
The valence electrons of different materials have different energies. The greater the energy of a valence electron, the lesser it is bound to the core. In particular substance like metal, valence electrons possess so much energy that’s why they are loosely bound to the core of an atom. These loosely attached valence electrons move at random within the material are called free electrons.
The valence electrons which are very loosely bound to the nucleus are known as free electrons.
The free electrons can be easily removed by supplying the small amount of external energy. Free Electrons can determine the electrical conductivity of a material.
A conductor is a material which has a large number of free electrons.
An insulator has no free electrons.
A semiconductor has few free electrons.