1 Energy Band Diagram :- The range of energies that an electron may possess in an atom is known as the energy band. There Important energy bands are, Valence Band Conduction Band Forbidden Band Valence Band :- The Range of Energy possessed by valence electrons is known as valence Bands. Conduction Band :- The valence electrons are less tightly bound with the nucleus. So that even an appication of small elctric field some of the valence electrons detached from the nucleus and it becomes free electrons. These fee elctrons are responsible for the conduction of current in good conductors. The electrons are also called conduction electrons. → The Range of energy possed by these elctrons is known as conduction band. Forbidden Band (or) Energy Gap :- The energy band in between the condition band and the valence band is called forbidden Band. Classification of Materials (or) Solids According to Energy Bands :- Solids are classified in to there types Insulators Conudctors Semi conductors Insulators :- → The materials in which the condition band and valence bands are separeated by a wide energy gap (≈ 15 eV) as shown in figure. → A wide energy gap means that a large amount of energy is required, to free the electrons, by moving them from the valence band into the condition band ; → Since at room temperature, the valence electrons of an insulator do not have enough energy to jump in to the condition, therefore insulator do not have an ability to