Why is there a point of orbits along with quantization in case of energy gaps?

Question

As per my textbook and online sources. The definition of Energy bands I have found is this:
A) Energy levels:

( In a simplified view of an electronic structure of a single atom or isolated molecule. Electrons can exist in quantised energy states each with a discrete energy value.)
Energy levels refers to specific or discrete energy values in a quantised energy state that an electron within a material can occupy.
B) Energy bands:
I) In case of an isolated atom , electrons move in specific orbits around the nucleus and each orbit correspond to a discrete & definite energy level.In a solid material , atoms are closely packed together. Due to this , electron clouds of neighbouring atoms start interacting with each other.
ii) This interaction causes the energy levels of the electrons in the same orbit to change slightly from their isolated atom values & electrons in the same orbit of a solid material to not possess a single, definite energy level anymore.
iii) Instead , The energy levels of these electrons spread out and form a continuous range of energies resembling a band rather than a single discrete energy level. Therefore , Energy bands refers to the continuous range of energies possessed by electrons in the same orbit of a solid material.

Q1: What the correct definition would be then ?
Q2: Why is there mention of energy bands in relation to the orbits around the nucleus and also mentioning electron clouds ( a topic of quantum mechanics ) , quantisation. Isn't that wrong ? Because quantum mechanics rejects the theory of electronic moving around the nucleus.

Answer 1

All statements are partially correct if you get rid of the classical term "orbit". Even if you use the term "orbitals", you will have some difficulty understanding solids, especially metals. The obvious transition from molecular orbitals to bands can be described by gradually increasing the conjugation of conjugated molecules. An atom is approximately described by the electrons in a spherical box (without any potential inside), if the box expands and the radius is large enough, the level will be closer and will form a band. An "orbit" is related to a spherical symmetry, while a solid tends to promote a translational symmetry. If you have no notion of QM, try to solve the case of a particle in a box, you will get bands by increasing the size of the box.