I was taught this in school but my teacher could not explain why the band splits again with decreasing atomic distance. Also, then i wondered how do you explain the fact the it splits again nicely into 4N states for the valence band and 4N states for the conduction band? Could some one help? Also, how would one redraw the above energy band diagram if the semiconductor was doped to become a n-type or a p-type? Hope someone could help! Thank You!