Niels Bohr was born in Copenhagen. His father, Christian Bohr, was a professor of physiology. His mother, Ellen Adler, was the daughter of a prominent Jewish family in Denmark. Bohr distinguished himself at the outset of his career and in 1907 he was awarded a gold medal by the Danish Royal Academy of Science for his Bachelor of Arts project.

Upon receiving his doctorate degree, Bohr went to England to study at Cambridge with J.J. Thomson, the discoverer of the electron. However, he became interested in the research of Ernest Rutherford on the structure of the atom and went to Manchester to work with him.

In 1913, he published his own model of the atom, a revolutionary theory that served as a cornerstone for twentieth century physics and earned him the Nobel Prize.

In 1916, he was appointed professor at the University of Copenhagen, and in 1920, he established the Institute of Theoretical Physics and was its director until his death.

Niels Bohr was likable and well rounded; in addition to his scientific work, he devoted his time to sport and even played on a football team.

In 1943, during the German occupation of Denmark, he fled to Sweden, from there to England and, later, to the U.S. where he participated in “the Manhattan Project” for the development and production of the atomic bomb. After the war, he did his utmost to prevent the proliferation of atomic weapons.

Niels Bohr died of a stroke on November 18, 1962, in Copenhagen, the city of his birth.

Niels Bohr was awarded the 1922 Nobel Prize in Physics, “for his contribution in research into the structure of the atom and the radiation it emits. His most outstanding achievement was the model of the structure of the atom that he published in 1913. This model integrated the quantum theory, still in its infancy, with atomic physics and provided answers to key questions puzzling physicists of that period.

Upon discovering that the atom has a positively charged nucleus and negatively charged electrons, physicists theorized that electrons circle about the nucleus like planets about the sun. According to the laws of classical physics, they would then lose energy and enter a spiral course which would consequently cause them to collapse into the nucleus. However, electrons are never found in the vicinity of the nucleus.

Furthermore, an examination of radiation released by atoms, particularly the hydrogen atom, reveals that this radiation is not emitted at all frequencies. Classical physics cannot explain the existence of “allowed” frequencies and “forbidden” ones.

To resolve this contradiction, Bohr proposed a solution deviating from classical physics: he determined that electrons circle about the nucleus only in certain circular “allowed” orbits, each one characterized by a particular value of energy. Electron do not give off energy while they are orbiting around the nucleus. When they pass from an orbit of higher energy to one of lower energy, However, they emit the difference in energy in the form of radiation. The radiation is thus released in units of energy corresponding to the differences in energy of the various orbits and is limited only to these units.

Bohr explained that radiation frequencies must correspond to the units of energy emitted from the electron. This idea corresponds to the theory that radiation is emitted in individual units of energy called “quanta”.

The Bohr model led to the development of quantum mechanics, one of the major scientific achievement of modern physics which explain a lot of phenomenons.