Which model did Neils Bohr develop to describe atomic structure?

Neils Bohr developed the planetary model to describe atomic structure, which fundamentally changed the understanding of how electrons are positioned around the nucleus of an atom. In this model, electrons travel in specific circular orbits around the positively charged nucleus, much like planets orbiting the sun. This idea introduced the concept of quantized energy levels, suggesting that electrons can only occupy certain allowed orbits and gain energy by moving to a higher orbit or lose energy by falling to a lower one.

The planetary model was groundbreaking because it provided a visual representation of atomic structure that was easier to understand while also introducing important principles of quantum mechanics. This model contrasted with earlier models that lacked the concept of quantized orbits, allowing for a more accurate explanation of atomic behavior, especially in explaining hydrogen's spectral lines.

Other models mentioned are either less relevant or do not pertain to Bohr's contributions. The spherical model does not adequately describe the behavior of electrons in terms of their energies and positions, while the cubic model does not exist in the sphere of atomic theory. The quantum model represents a more advanced understanding of atomic structure that evolved after Bohr and incorporates more complex principles of quantum mechanics.