Question

in terms of band theory what is the difference between a conductor and an insulator.​

Answer 1

Answer:

in conductors the gap between valence band and conduction band is little so electrons can jump from one to other

but in insulator the gap is very large and electrons cannot jump through so no free electrons become available for electrical conduction.

Answer 2

In conductor, the valence band is partially filled and it overlaps with a high energy unoccupied conduction band. Electrons can easily flow under an applied electric field. In case of insulator, the valence band is fully-filled and there is large energy gap between the valence band and the conduction band.