Atoms and energy levels question

[eis3nheim]

As the atoms of a material are brought closer together to form the crystal lattice structure, there is an interaction between atoms, which will result in the electrons of a particular shell of an atom having slightly different energy levels from electrons in the same orbit of an adjoining atom. The result is an expansion of the fixed, discrete energy levels of the valence electrons. In other words, the valence electrons in a silicon material can have varying
energy levels as long as they fall within the band .

 

[Quantum Defect]

As the atoms of a material are brought closer together to form the crystal lattice structure, there is an interaction between atoms, which will result in the electrons of a particular shell of an atom having slightly different energy levels from electrons in the same orbit of an adjoining atom. The result is an expansion of the fixed, discrete energy levels of the valence electrons. In other words, the valence electrons in a silicon material can have varying
energy levels as long as they fall within the band .

Similar to what happens when you bring two H atoms together. The energies of the 1s "orbitals" split into a lower energy "bonding molecular orbital" and a higher energy "antibonding molecular orbital." (Higher and lower are also wrt the energies of the isolated H atoms' 1s energy levels.)

If you bring in three atoms, you get three levels; if you bring in what amounts to infinite atoms, you get an infinity of levels -- essentially a "band" of allowed energies. I wouldn't really say that the levels are confined to one atom or the next. In the molecular case, the "orbitals" are delocalized over both atoms. it doesn't make sense to say that the lower energy level sits on one of the atoms or the other, these are electronic states that are delocalized over the whole molecule.

 

[eis3nheim]

Similar to what happens when you bring two H atoms together. The energies of the 1s "orbitals" split into a lower energy "bonding molecular orbital" and a higher energy "antibonding molecular orbital." (Higher and lower are also wrt the energies of the isolated H atoms' 1s energy levels.)

If you bring in three atoms, you get three levels; if you bring in what amounts to infinite atoms, you get an infinity of levels -- essentially a "band" of allowed energies. I wouldn't really say that the levels are confined to one atom or the next. In the molecular case, the "orbitals" are delocalized over both atoms. it doesn't make sense to say that the lower energy level sits on one of the atoms or the other, these are electronic states that are delocalized over the whole molecule.

Would you explain more.