The Atomic bomb
The atomic bomb was one of our world greatest and most deadly scientific achievement. The science behind it was evolutionary and changed the world. but like everything we do this discovery was two sided. we have the brilliant advancement of science and the devastating regret of the worst weapon so far imagined. Behind this achievement were a lot of scientist working very hard and struggling to advance our societies understanding of unstable isotopes. To fully understand what lead to the development if the atomic bomb we must start at the beginning and first understand what is an atom and an isotope and how did we come to understand them the way we do now.
The Atom
An atom is the smallest unit of matter that still retains the properties of the element. For example an atom of gold is the smallest unit of gold you can get until the particle is no longer considered gold. While an is the smallest unit of matter still recognized as a certain element it itself is made up of smaller particles called subatomic particles, these particles are proton neutrons and electrons. The atom is made up of two parts a nucleus and electron cloud.
Parts of the atom
The Nucleus
The nucleus is the center of the atom and contains protons and neutrons. If you want to relate the atom to something you can see think of baseball field. The nucleus would be the pitchers mound, the neutrons would be the baseball and the protons would the bag of chalk the pitcher holds. The stands would be the electron cloud and vendors would be electrons.
The electron cloud
The electron cloud is a general region in which electrons travel and can never be truly seen unlike in the previous example where the electrons were vendors. The electron cloud is outside of the nucleus and is made up of several orbitals or layers if you will.
The atom as we know it
Our understanding of the atom has changed drastically over the years from ancient Greek to today the atom has gone from a solid ball to the smallest unit of matter made up of subatomic particles. There were several scientist behind the development of the atomic model and each one has a part in figuring out parts of the whole. Each of these scientist were at the forefront of their field making discoveries that changed the path of scientific discovery.
Atomic models
| Scientist | year | theory | model |
|---|---|---|---|
| Democritus | 442 B.C. | All matter consisted of invisible particles called atoms and a void. These atoms are indestructible and unchangeable. His model was solid stating that all atoms were differed in size, shape, mass, position, and arrangement.
Coined the name “atomos” meaning Indivisible |
Example |
| Dalton | 1803 | Elements consist of tiny particles called atoms.
Atoms of the same element were uniform having the same shape, size and mass. Different atoms have different shapes, sizes and masses. Atoms combine to form compounds. |
Billiard ball model |
| J.J. Thompson | 1904 | An atom is made of positively charged fluid (the pudding) in this fluid was negative particles scattered around (the raisins) | Plum Pudding Model |
| Rutherford | 1911 | Proposed that the atom contained a small dense positively charged center. He named this center the nucleus. The nucleus was surrounded by negative charges. | Planetary Model |
| Bohr | 1913 | Atoms had a dense positive nucleus. Electrons moved in a fixed circular orbit called an electron shells or energy levels around the nucleus. Each shell was a fixed distance from the nucleus. | Energy level model |
| Schrodinger | 1926 | A dense nucleus surrounded by a cloud of electrons in various levels called orbitals. These clouds determined the best likely location of electrons. | Electron cloud model |
The Manhattan Project
The Manhattan Project was the code name for the research and development project for the creation of the atomic bomb. The main reason behind the Manhattan Project was they fear that Germany was developing their own atomic bomb. Something that would have been devastating creating a world entirely different. As luck would have it Germany's work on the atomic bomb stalled in 1942 about the same time U.S. effort to produce an atomic bomb began in earnest.
Locations of the Manhattan Project
To keep the project safe and secure several locations were used as research and development sites. During the project over thirty locations were used for research but only three were the main locations of research. These three sites included Hanford, Washington, Oak Ridge, Tennessee and Los Alamos, New Mexico. Hanford, Washington was the location used for the production of plutonium for the atomic bombs. Scientist at Oak Ridge, Tennessee were tasked with designing reactors which could produce plutonium and later to produce the U-235 isotope of uranium at a purity and quantity to make an atomic bomb. In Los Alamos, New Mexico scientist designed and built the first atomic bombs. in the end two different kind of bombs were produced one a gun-type weapon using the bomb as a bullet and another that used implosion to detonate plutonium.
The scientist behind the Manhattan Project
The research and development of the atomic theory began many years before the actual production of the atomic bombs used during world war II to bring about the end of the war. In 1899 Ernest Rutherford identified two different types of natural radiation alpha particle (a helium nucleus emitted by some radioactive substances) and beta rays (a fast-moving electron emitted by radioactive decay of substances). This was followed by P.V. Villard discovery of a third type of natural radiation in 1900 called gamma rays (penetrating electromagnetic radiation of a kind arising from the radioactive decay of atomic nuclei). The discovery of natural radiation was the spark that started the firestorm of discoveries surrounding the production of the atom and the atomic bomb. While we now knew of three kinds of natural radiation scientist had not even explained the atom as a whole a lot was still left to discover. It would take many years until the atom was explain in full and scientist would move on to the next steps in discoveries. In 1933 Hungarian physicist Leo Szilard first comes up with the concept of a nuclear chain reaction and the possibility of an atomic bomb. Following this discovery is the discovery of artificial radioactivity by Irene Curie and Frederic Joliot this promoted Enrico Fermi to bombard elements with neutrons a split uranium without realizing it. Following in his footsteps was Otto Hahn and Fritz Strassmann who purposely split uranium in 1938 this phenomenon was later explained by Lise Meitner and Otto Frisch as nuclear fission in 1938. Not long after this in 1939 Germany invades Poland starting World War II setting into motion the catastrophic events that would lead to the dropping of atomic bombs on Japan.
In 1941 President Roosevelt asked Vahhevar Bush the man who established the Office of Scientific research and development (OSRD)to determine the cost of an atomic bomb. Later that same year Japan attacked Pear Harbor and United States declared war on Japan which was responded to by Germany Italy declaring war on the United States. In 1942 Roosevelt approved the production of an atomic bomb and an order is issued formally establishing the Manhattan Engineer District. Oak Ridge was selected as the site for the pilot plant in September of 1942 at this site designs would be made and uranium would be purified. Los Alamos was later selected as a site to design and produce the atomic bombs, Oppenheimer was chosen as the director for this site. In major discovery and turning point in the development of the atomic bomb Fermi and his team produced the first sustained nuclear fission chain-reaction in December of 1942. Now was the time to start developing the atomic bomb and gathering plutonium and uranium for this reason a new site (Hanford, Washington) was chosen in 1943 for plutonium production.
In 1945 President Roosevelt dies and the war starts to dwindle with Nazi Germany surrendering to allies. Italy had already surrendered two years prior in 1943 and all that seemed to be in the way of peace was Japan. Now was the time to finalize the atomic bomb with a test and then dropping it in Japan to end the war. The first nuclear explosion took place in Alamogordo, New Mexico on July 16th 1945. Now was the time to drop our nuclear bombs on Japan in the chosen cities.
The bombs themselves
Two different types of bombs were developed "Little Boy" and "Fat Man"
Little Boy
A gun-type device where the bullet being the atomic bomb itself. It has a total mass of 9,700 lbs and was 10 ft long with a 28 inch diameter. Little Boy was the first bomb dropped in the war. It bomb made of uranium and had the explosive force of 15,000 tons of TNT with only 1.38% of the uranium being used in fission making it an inefficient weapon.
Fat Man
The fat man was an implosion type bomb made up of plutonium and was the only bomb actually tested before its use. The core of this bomb was sub-critical plutonium surrounded by several thousand pounds of high-explosive. It was designed in a way that the explosive force of the high explosive would be directed inward and crush the core causing it to go into a super-critical state. the bomb weighed 10,800 lbs and was 10 ft 8 in in length with a diameter of 60 in this bomb was much more efficient that the little boy.
History behind the dropping of the atomic bomb
The purpose of the atomic bomb was to develop a weapon that could end the war in Japan with very few American casualties. While it was known the results it was still considered the best solution despite the scientist disapproval of the whole event. many scientist felt that since Germany had stopped work on their atomic device in 1942 there was no reason to continue the development of atomic bomb.
The cities chosen
To chose the cities the bobs would be dropped on a committee was created to decide which cities would be the best choice, the ones that would make the most impact. The criteria for a chosen city was as follow; the city must be an area that when bombed would destroy the Japanese peoples will to fight, be of a large diameter to contain the blast, the city should be military in nature such as a head quarter, and not previously hit by air raids with the likely hood they would reminded undamaged by August. the committee started with seventeen cities which they narrowed down to five then the two that little boy and fat man were dropped on.
Little boy was the first atomic bomb dropped on the Japanese city of Hiroshima; August 6, 1945. While the bomb was ineffective it still devastated the Japanese population killing more that 80,000 people and causing millions in damaged. Fat boy was the only atomic bomb tested and the second to be dropped on the Japanese city of Nagasaki on August 9, 1945. Fat boy was a more efficient bomb being ten times more efficient than little boy, while more efficient it still caused similar damage and causalities.
References
- http://www.u-s-history.com/pages/h1644.html
- http://sciencepark.etacude.com/chemistry/basic1.php
- http://www.solpass.org/science6-8-new/standards/standard_ps3.html?section=study-2
- http://www.atomicheritage.org/history/little-boy-and-fat-man
- Kelly, C The Manhattan Project
- Rhodes, R The making of the atomic bomb