What is Bohr's atomic model

The Bohr model is a relatively primitive model of the <a href="https://en.wikipedia.org/wiki/Hydrogen_atom" title="Hydrogen atom">hydrogen atom</a>, compared to the <a href="https://en.wikipedia.org/wiki/Atomic_orbital" title="Atomic orbital">valence shell atom</a>. As a theory, it can be derived as a <a class="mw-redirect" href="https://en.wikipedia.org/wiki/Orders_of_approximation#First-order" title="Orders of approximation">first-order approximation</a> of the hydrogen atom using the broader and much more accurate <a href="https://en.wikipedia.org/wiki/Quantum_mechanics" title="Quantum mechanics">quantum mechanics</a> and thus may be considered to be an <a class="mw-redirect" href="https://en.wikipedia.org/wiki/Obsolete_scientific_theory" title="Obsolete scientific theory">obsolete scientific theory</a>. However, because of its simplicity, and its correct results for selected systems (see below for application), the Bohr model is still commonly taught to introduce students to <a href="https://en.wikipedia.org/wiki/Quantum_mechanics" title="Quantum mechanics">quantum mechanics</a> or <a href="https://en.wikipedia.org/wiki/Energy_level#Energy_level_diagrams" title="Energy level">energy level diagrams</a> before moving on to the more accurate, but more complex, valence shell atom. A related model was originally proposed by <a href="https://en.wikipedia.org/wiki/Arthur_Erich_Haas" title="Arthur Erich Haas">Arthur Erich Haas</a> in 1910, but was rejected. The quantum theory of the period between <a class="mw-redirect" href="https://en.wikipedia.org/wiki/Planck#Black-body_radiation" title="Planck">Planck's discovery of the quantum</a> (1900) and the advent of a full-blown <a href="https://en.wikipedia.org/wiki/Quantum_mechanics" title="Quantum mechanics">quantum mechanics</a> (1925) is often referred to as the <a href="https://en.wikipedia.org/wiki/Old_quantum_theory" title="Old quantum theory">old quantum theory</a>