Final answer:
Niels Bohr discovered Bohr's atomic model, which explained the atomic spectrum of hydrogen and established new principles in quantum mechanics.
Step-by-step explanation:
Niels Bohr discovered the model of the atom, known as Bohr's atomic model, which he proposed in 1913. His model explained the atomic spectrum of hydrogen and established new principles in quantum mechanics. The key idea of Bohr's model was that electrons orbit the nucleus at fixed distances, in what he referred to as stationary states.