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