What is energy gap in bond theory?

What is energy gap in band theory? Compare its size in Conductors, semi Conductors and insulators?

What is energy gap in Band theory? Compare its size in conductors, semiconductors and insulators. Or Define the 'Forbidden zone' of an insulator.

What is the energy gap in Si semiconductor?

What is bond energy ?

In a good conductor, what is the energy gap between the conduction band and the valence band.?

In a good conductor, what is the energy gap between the conduction band and the valence band.?