Niels Bohr

1. Niels Bohr -NielsHenrik David Bohr was bored in Copenhagen, Denmark on October 7, 1885 and died in Copenhagen on November 18, 1962

2. Family & Heritage -Bohrs Father, Christian Bohr, was a professor of Physiology at the University of Copenhagen -Ellen Adler, his mother, came from a Jewish family -His brother, Herald, became a mathematician, and was thought to be a lot brighter then Niels in their younger years. -In August of 1912 Bohr married to Margrethe Norlund. They had six sons together, but two died at a very young age.

3. Bohr’s Education & Research • -Bohr attended the University of Copenhagen in the year 1906. • -On his first research project he won a gold medal from the Academy of sciences. His project involved precise measurement of the surface tension of water. • -He received his PhD in the year 1911, and his dissertation was “Studier over Metallerness Elektrontheori”. Today it is still seen as a classic when it comes to the field of electron theory of metals. • -A major bump in his education was the Cambridge Philosophical society rejected his dissertation.

4. Niel during the war • -Niel remained in Copenhagen during the 40’s when Hitler was in control. He left Denmark in the year 1943 and headed to Sweden. • -During his stay in Sweden he helped many Jewish people from Hitlers’ gas oven. • -He also came to the United States and worked on the atomic bomb at Los Alamos.

5. Bohr’s work toward Quantum Theory • -After his education he went to the Cavendish labs in Cambridge, England with hopes to work with J.J, Thompson, but J.J. Thompson had already lost interest. • -After realizing J.J. Thompson had lost interest, Bohr moved to Manchester in the year 1912 to work with Rutherford. • -Through his work with Ernest Rutherford they were able to lay the theory of atomic constitution. • -Bohr and Rutherford used the solar system as a way to describe what the atom might look like • -Rutherford had previously done an experiment in which he shot large alpha particles at a thin gold foil. When he did this he discovered that most of the light passed right through, but some actually went off at different angles (possibly deflected). This allowed him to conclude that most was made of empty space, but it did contain a space which was denser (where no alpha particles were able to pass through). Since this dense area deflected the positively charged alpha particles, he concluded this dense space had an overall positive charge.

6. Quantum Theory Con’t • -Bohr described how electrons would orbit around the nucleus, and how this represents different energy levels. He stated that an electron cannot exist between the energy levels, quantized energy levels. He said that the orbits which were closer to the nucleus had a lower energy then the orbits that were further from the nucleus. • -Bohr also proposed that when energy is added to an electron , in the form of a photon, it can jump up to a higher energy level and moves further from the nucleus. • -Bohr was able to explain how the electron went back down to a lower energy level , through photon emission. The difference in these energy levels would be the amount of energy released. The energy could be released in many different ways. It could be released in visible light, x-rays, or other parts of the electromagnetic spectra. • -Bohr’s idea of quantized energy levels fixed a major problem associated with the atom, but at the same time was slightly wrong with his idea of the amount of energy that is released when an electron drops energy levels. Bohr’s idea seemed to work for hydrogen, but not for much larger atoms. • -Erwin Schrodinger later proposed the idea that an electron could be both a wave and a particle. With this in mind he was able to find the probability of an electron being in a specific place.

7. Nobel Laureate • -Bohr received the Noble Prize in the year 1922 due to his work on atomic structure.