JJ Thomson was a British Physicist who was born in England in 1856 and died in 1940 at the age of 83. He won a Nobel Peace Prize for Physics in 1906 for his work with cathode rays and electrons. He theorized that the atom was able to be broken apart into smaller pieces and that the fundamental unit was over 1000 times smaller than the actual atom. His results in his experiments led to the discovery of the electron and the charge-­‐to-­‐mass ratio of the electron. Robert Millikan was an American Physicist born in Illinois in 1868. He died in 1953 at the age of 85. He won the Nobel Peace Prize in Physics in 1923 for his work with the charge of electrons. Millikan and one of his graduate students used an oil drum to find the charge of a single electron particle. Once he knew that, he could use the ratio of charge-­‐to-­‐mass of an electron to calculate its mass. Niels Bohr was a Danish physicist who was born in 1885 and died in 1962 at the age of 77. He won the Nobel Peace Prize in Physics in 1922 for his work on quantum theory. He made an accurate model of a hydrogen molecule. In his model, the electrons orbited around the central atomic nucleus and they could move from energy level to energy level. He modeled his atom after Ernest Rutherford’s nuclear structure and the quantum theory of Max Planck. Louis de Broglie was a French physicist who was born in 1892 and lived for 94 years before his death in 1987. He won the Nobel Peace Prize for Physics in 1929 for his work in quantum theory. He hypothesized the wave nature of electrons. Additionally he postulated that all matter has wave properties. Werner Heisenberg was a German theoretical physicist who was born in 1901 and died in 1976 at the age of 74. He won the Nobel Peace Prize for Physics in 1932 because he was one of the important founders of quantum mechanics. Additionally he published a paper in which he created a model of the nucleus of atoms. Erwin Schrodinger was an Austrian physicist who was born in 1887 and died in 1961 at the age of 73. He won the Nobel Peace Prize for Physics in 1933. He did work on quantum theory along with wave mechanics. He also studied the orbit of electrons around the nucleus. His worked proved that the quantum orbits were associated with certain geometric properties. He also constructed the quantum mechanical model of the atom. Bohr’s Model was an atomic model made by Bohr based on Ernest Rutherford’s nuclear structure and the quantum theory of Max Planck; however, it only was accurate for a hydrogen atom. In the model, the electrons orbit in a set course around the nucleus. Schrodinger’s quantum mechanical model replaced Bohr’s because Schrodinger’s was more accurate. The quantum mechanical model was made by Schrodinger following his studies of the orbit of electrons. His model accurately shows how the electrons orbit around the nucleus in relation to the radius. This model was more accurate than Bohr’s because it worked for all of the elements. Bohr’s model only worked for a hydrogen atom. Schrodinger used Heisenberg’s model of the nucleus in his quantum mechanical model. Thomson did the cathode ray experiments in order to prove his theories and Millikan did the oil drop experiment to prove his. The theories and models fit into the last few years of the history of atom theory. All of the models and theories were discovered and theorized in the span of about 33 years. Even though they happened some time ago, there hasn’t been much more development into atom theory. Bohr’s model of the atom was partially correct and partially incorrect. It worked for only the hydrogen model. Broglie’s thesis on wave nature of electrons held up over time. The quantum mechanical model that Schrodinger made was correct for all elements and Heisenberg’s model of the nucleus also held its own over the years. Planck’s quantum theory was an influence to Bohr’s model and it was correct. Thomson’s plum pudding model of the atom was incorrect and replaced by both Bohr’s model, which was incorrect for all atoms but hydrogen atoms, and the quantum mechanical model, which was correct for all atoms.