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Niels Bohr - Danish Physicist Extraordinaire

© Jackie DiGiovanni

Niels Henrik David Bohr was born October 7, 1885, in Copenhagen. His parents, Christian and Ellen (Adler) Bohr were from respected, well-to-do families. Christian Bohr was a professor of physiology at Copenhagen University. He enjoyed bringing educated, interesting people to his home for dinner and conversation, and his children were exposed to great ideas and current thinking. Ellen Bohr felt more comfortable giving birth to her children in her mother's home, a large house opposite Christiansborg Castle where the Danish parliament met. There were three children in the family. Bohr's sister was Jenny and his younger brother was Harald (who would win an Olympic silver medal in soccer and become a professor of mathematics). The brothers were inseparable throughout their lives. 

Bohr finished Gammelholm Grammar School in 1903. He was a good student and excelled in physics and mathematics. He was also a good athlete. It is probable that he learned a great deal from his father who gave him access to his laboratory. After graduation, Bohr began studies at Copenhagen University. He studied physics, mathematics, astronomy, and chemistry. He studied under Christian Christiansen, Harald Hoffding, and Thorvald Thiele. There was no physics laboratory at the university, so he did his research at the physiology laboratory in this father's department. In 1907, he was awarded the gold medal of the Royal Danish Academy of Sciences and Letters for his essay on determining the surface tension of liquids. 

Bohr received a master's degree in physics in 1909, and a doctor's degree in 1911. His doctoral thesis was on the electron theory of metals.

He received a grant from the Carlsberg Foundation and went to England in 1911 to study and conduct research with Sir J J Thomson (discovered the electron) at Cambridge. Bohr and Thomson were not well suited to each other, so after a few months, Bohr changed to Victoria University in Manchester (University of Manchester) working with Ernest Rutherford. Rutherford had just published a paper describing the theory that most of the mass of an atom was in its nucleus. 

He married Margrethe Nørlund on August 1, 1912. They had six sons, four of whom survived. One son is Aage Bohr, who also received a Nobel Prize in physics.

Bohr returned to the University of Copenhagen in 1912. He extended Rutherford's theory, using the quantum ideas of Planck, to describe how electrons in an atom travel around a nucleus in various set orbits, that the outer orbits hold more electrons than inner orbits, and that outer orbits determine the atom's chemical properties. Bohr also described how atoms might emit radiation when an electron jumped from an outer orbit to an inner orbit. He