Niels Bohr first presented his atomic model in 1913.
Bohr published the model in a series of three papers in the Philosophical Magazine during July, September, and November 1913. He built on Ernest Rutherford’s 1911 discovery of the atomic nucleus and combined Rutherford’s nuclear atom with emerging ideas from Max Planck’s quantum theory.
The model proposed that electrons could occupy stable, quantized energy levels rather than radiating energy continuously and spiraling into the nucleus, as classical physics seemed to imply. Electrons could move between those levels by absorbing or emitting discrete amounts of energy. This helped explain the observed spectral lines of hydrogen, including the Balmer series.
The 1913 model was a major breakthrough but was not the final description of the atom. Modern quantum mechanics replaced its fixed electron orbits with orbitals and probability distributions. Even so, the Bohr model remains an important teaching model and a crucial step in the history of quantum physics.