Niels Bohr and Atomic Energy Levels By Nina Sellers and Shelby Cramer 1 1

Niels Bohr: A Biography Full name: Niels Henrik David Bohr Born October 7th, 1885 Died November 18th, 1962 Born in Copenhagen, Denmark 2 2

Niels Bohr: A Biography Went to many different schools, including Gammelholm Latin School, and Copenhagen University Danish Physicist; studied under Christian Christiansen, the only physics professor at the time Also studied mathematics and astronomy Known for the Bohr model 3 3

Most Important Work Helped contribute to the understanding of the structure of an atom and quantum theory In order to graduate, he wrote an important thesis on the electron theory of metals In 1921, the Dutch physicist Hendrika Johanna van Leeuwen would independently derive a theorem from Bohr's thesis that is today known as the Bohr-van Leeuwen theorem He read into it, and eventually decided on a model by Paul Drude and elaborated by Hendrik Lorentz. The model demonstrated how electrons in a metal seem like a gas 4 4

The Bohr Model of the Atom Electron's energy levels in the atom: to find the electron capacity, the formula is 2n^2 The variable n represents the number of the energy level

Most Important Work (cont'd.) Despite his research and overall knowledge on the topic, he failed to explain the Hall Effect (the voltage difference made across a conductor of electricity) Concluded that his theory failed to explain other metal's magnetic properties Since his these was written in Dutch, it was not understood by many outside of Scandinavia Even with this setback, it was still a groundbreaking event for science 6 6

Why it's important He adapted Rutherford's nuclear structure to Max Planck's quantum theory and so created his Bohr Model of the atom. Energy levels (discrete) Introduced the idea of electrons being able to drop into a lower-energy orbit from a higher one, and whilst doing this, give off a quantum of discrete energy This was the basis for the old quantum theory 7 7

Importance of Atomic Spectra Substances that are not known can now be known by adding heat and observing the specific frequency of light that is emitted Light can also be shown onto them to see the frequencies that are absorbed This can be applied to analyze any substance (even elements that are in space and planets!)

Why it's important (cont'd) Without Bohr's experiments and his insight on atomic energy levels, our understanding of atoms (in general and their charges) would be minimal Due to his diagram and discovery of the atom, big advances in technology were able to be made 9 9

Bohr's Involvement Involvement in development of atomic theory: Due to his breakthrough with the understanding of the atom, he inadvertently helped with the atomic bomb in the Manhattan Project (as did others like Einstein) Made theories about the structures of atoms and through models and research proved what was soon to be a breakthrough The Bohr Model of atomic structure was the core of all future theories regarding quantum mechanics 10 10

The Bohr model of the Hydrogen Atom Pictures The Bohr model of the Hydrogen Atom Negatively charged electron orbits a small positively charged nucleus Quantum jump between orbits with help from an absorbed amount of electromagnetic radiation 11 11