The Manhattan Project was an attempt to develop the first atomic bomb. Scientist Albert Einstein, fled Nazi persecution, and Enrico Fermi, escaped Fascist Italy, both of them refugeed to the United States. They had learned about Germany’s scientist had been working on a weapon using nuclear technology and Adolf Hitler was prepared to use it in war. They agreed upon writing a letter informing President Roosevelt about what German scientist were doing in Germany.
President Roosevelt responded by assembling a team of the best scientist and military officials called the Uranium Committee. They researched uranium and its potential use as a weapon. In the early 1940’s the U.S government began to organize and fund nuclear research. Fermi and Szilard’s research was funded by the government, they were researching radioactive isotope separation and nuclear chain reactions.
Leo Szilard theory was that nuclear material could react in the same way as a chemical chain reaction. If a neutron form one atom can be used to cause an energy producing reaction in another atom a chain reaction could form releasing more neutrons generating more reactions. When man discovers how to make that chain reaction occur a nuclear bomb can be made. The Uranium Committee primary focus was to isolate enough uranium to create the chain reaction Szilard theorized.
Most of the natural uranium in the world is primarily of U-235 (0.7% natural abundance) and U-238 (99% natural abundance). When neutrons collide with U-235, it emits huge amounts of energy through a fission reaction, whereas U-238 is less fissile then U-235. The committee was trying to figure out how to separate the U-235 from the U-238, they eventually discovered that it could be done by combining uranium with fluorine to form a gas that could be filtered to extract the isotope that they wanted. But then, they had to figure out how much uranium-235 was needed to achieve critical mass, the smallest amount of fissile material necessary to sustain a nuclear chain reaction. After that, they just had to figure out how fast a neutron had to be fired at the uranium atom to trigger a reaction.