In 1911, Bohr received his doctorate from Copenhagen University. After graduation, he attended Victoria University of Manchester in England where he studied under Ernest Rutherford. Under Rutherford's theories Bohr published his model of atomic structure (1913) and introduced the theory of electrons orbiting around the atom's nucleus and stated that the element's properties are largely determined by the number of electrons in the electron cloud. He also introduced the idea of electrons dropping from a higher-energy orbit to a lower one could emit a photon of discrete energy. These findings later became known as the quantum theory.
In 1916, Niels Bohr became a professor for the University of Copenhagen and director of the Institute of Theoretical Physics in 1920. In 1922, he was awarded the Nobel Prize in physics for his investigation of the atom. Bohr later went on to conceive the principle of complementarity, that items can be analyzed seperately as having contradictory properties. Bohr met with Albert Einstein to debate the truth of the principles. Bohr's most famous student was Werner Heisenberg, who helped develop quantum mechanics and was the head of the German atomic bomb project.
In 1943, Bohr was to be arrested by the German police. However, Bohr escaped to Sweden and later to London before an arrest could be made. From there, Bohr went to the USA and secretly worked on the Manhattan Project at the Los Alamos laboratory under the name "Nicholas Baker" for security reasons. His role on the project were extremely important and was seen as the knowledgeable consultant or "father confessor" of the project. However, when asked of the nuclear arms race, Bohr stated "That is why I went to America. They didn't need my help in making the atom bomb."
Bohr believed the atomic secrets should be shared with the international community. After meeting with President Franklin Roosevelt, the two agreed the results should be shared with the Russians in order to speed the process. However, when Bohr returned to England to ask for approval from Churchill, the Prime Minister opposed the idea. After the war had ended, Bohr returned to his native Copenhagen and advocated for the peaceful use of nuclear energy. Niels Bohr died in Copenhagen in 1962. The element bohrium was named in his honor and his picture was put on the 500 kr. Danish bank note.