----1915-1950


 * __James Chadwick__**

James Chadwick discovered the neutron in 1932, and was awarded the Nobel Prize in 1935. Chadwick’s experiment consisted of hitting beryllium with alpha particles which forced it to emit what turned out to be neutrons. The particles that were emitted were proved to be neutral by putting a magnetic field around them and observing that they did not react at all. Also these rays could also penetrate 200 mm of lead when an proton could penetrate only 2 mm. if a proton was to penetrate that far it would have taken more then triple the energy put into the beryllium. Chadwick proved the neutron existed and had an approximate weight of 1 and charge of 0. James Chadwick was born in England 1891, and went to Manchester high school, then Manchester University in 1908. He continued his scientific career under Earnest Rutherford, earning a masters degree then proving the existence of the neutron.

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Bohr was responsible for the latest and greatest atomic model, the one that we believe today. He began to explain why the electrons orbit the way they do and how they do not crash in on the nucleus. He was the first to theorize quantum mechanics. He explained how electrons gain energy and leap from level to level away from the nucleus. When electrons gain energy they jump out orbits, and when they lose energy they emit light as the move inward. He also believed that electron can only be on an orbit and never in between. Neils Bohr lived from 1885 to 1962. He studied at Copenhagen university first philosophy then physics. He then studied under Earnest Rutherford. He earned the Noble Prize for Physics in 1922, for his work with quantum mechanics. [] []
 * __Neils Bohr__**

**__Werner Heisenberg__** Heisenberg discovered the uncertainty principle, which states that one can never know the precise location and velocity of anything at the atomic level. Due to the fact that light has momentum, and it is required to observe the particle as soon as it is observed it changes. The momentum of the light hits the particle and alters its place and velocity. In normal physics the precise velocity and position of an object can be observed. In quantum physics it cannot. Heisenberg was born in Germany in 1901. He studied at the University of Munich where he earned his PhD in physics. Heisenberg then became a professor and was very involved with the creation of the Max Plank institute for physics as well as giving lectures around the world. []

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** Erwin Schrödinger ** Erwin Schrödinger was born on August 12, 1887, in Vienna. He made his discovery in 1933. Schrödinger was a student at the University of Vienna from 1906 to 1910. After Vienna he went on to World War 1, and then to University of Zürich in 1921 where he remained for six years. He went on to write papers about specific heats of solids, and problems of thermodynamics and of atomic spectra, Also he indulged in physiological studies of color. Later he paired up with Paul Dirac, and proved his aversion of the quantum condition in Bohr’s orbit theory and belief that atomic spectra should really be established by some kind of mathematical problem. The discovery that Erwin Schrödinger made pertained to Quantum Physics. By this he was able to describe the paths that electrons would most likely follow in their orbit around the nucleus. The formula that Schrödinger developed in 1926 was later known as the basics of quantum mechanics. These studies awarded him the Nobel Prize in 1933. Later he discovered that there is not a pre-determined path of where elections orbit, they are just moving around in an area. All of these had new quantum mechanical formulas, and were presented in the “Wave Mechanical formula” which is the basic modern atomic theory. This went on to make the Electron Cloud Model. [] [] [] []

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