Levels of Energy Bands #8211; We call these set of energy levels as energy bands. (i) Valence Band. The electrons in the outermost shell are known as valence electrons (ii) Conduction Band (iii) Forbidden Energy Gap (iv) Conductors (v)Insulators (vi) Semiconductors (vii) Formation of Energy Bands. In an isolated atom, the electrons in each orbit possess definite energy.