In my chemistry textbook, the chapter "Structure of Atom" deals with the old Bohr's model and the new Quantum mechanical model. But when I read the contents of the new model of atom, there were terms like energy levels, shells being repeated. I failed to understand the context. Moreover, Bohr's model has been discarded so why do we still talk about energy levels/ orbits in an atom?

Basically, I want a satisfactory explanation of these terms: energy levels, orbits, sub orbits, shells, sub-shells, orbitals and principal quantum number in accordance with the Quantum mechanical model of the atom.

I tried to understand this from two other books but there too the distinction was vague.

I also read the contents of:

Is there a difference between energy levels and electron shells?


PS: Please provide an answer keeping in mind that the questioner is a Grade 11 student.

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    $\begingroup$ There are no orbits, suborbits, and subshells in QM. $\endgroup$ – Zhe Jun 23 '17 at 13:08
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    $\begingroup$ What is the problem with the common QM definition of shell, subshell etc? $\endgroup$ – Greg Jun 23 '17 at 13:12
  • $\begingroup$ So, does the book not provide definitions of those terms? Or are you confused about those terms? $\endgroup$ – Jon Custer Jun 23 '17 at 15:40
  • $\begingroup$ @Greg I can't tell if that comment is directed at my comment or the OP. $\endgroup$ – Zhe Jun 23 '17 at 20:51