Why the motion of electron in solid and in an isolated atom is different ?

Explanation

According to the Bohr atomic model the electrons in the atom move in a different orbit around the nucleus so the energy of any electron depends on the orbit it is in.
When the atoms come together to form a solid they are close to each other. So the outer orbits of electrons from neighbouring atoms would come very close or could overlap, that is they merge into each other.
Due to this reason the motion of electron in solid and in an isolated atom is very different.