Template:POTD/2021-10-07
Niels Bohr (7 October 1885 – 18 November 1962) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory. He advanced the theory of electrons travelling in orbits around the atom's nucleus, with the chemical properties of each element being largely determined by the number of electrons in the outer orbits of its atoms. He introduced the idea that an electron could drop from a higher-energy orbit to a lower one, in the process emitting a quantum of discrete energy. For his work, he received the Nobel Prize in Physics in 1922.Photograph credit: Bain News Service; restored by Bammesk