1. Split The Atom

By the way, the most amazing thing about the wikiHow on how to split an atom — other than the fact that there is a wikiHow on how to split an atom — is the warning at the end: “As with any. Also referred to as nuclear fission, splitting an atom results in its overall mass being reduced, causing the release of a relatively massive amount of energy. Virtually every atom can generate nuclear energy in this way, but those with the greatest atomic mass will provide the most energy from fission. Splitting an atom or nuclear fission is a saying we hear from time to time. After the discovery of the nucleus in the atom in 1911, it was found that these atomic nuclei, which were bombarded with particles from radioactive substances, could breakdown and eventually produce a large amount of energy. Unauthorised History looks at the origins of nuclear energy in which the father of nuclear physics, Ernest Rutherford, splits the atom in 1917.

The immense destructive power of atomic weapons derives from a sudden release of energy produced by splitting the nuclei of the fissile elements making up the bombs' core. The U.S. developed two types of atomic bombs during the Second World War. The first, Little Boy, was a gun-type weapon with a uranium core. Little Boy was dropped on Hiroshima. The second weapon, dropped on Nagasaki, was called Fat Man and was an implosion-type device with a plutonium core.

Fission

The isotopes uranium-235 and plutonium-239 were selected by the atomic scientists because they readily undergo fission. Fission occurs when a neutron strikes the nucleus of either isotope, splitting the nucleus into fragments and releasing a tremendous amount of energy. The fission process becomes self-sustaining as neutrons produced by the splitting of atom strike nearby nuclei and produce more fission. This is known as a chain reaction and is what causes an atomic explosion.

When a uranium-235 atom absorbs a neutron and fissions into two new atoms, it releases three new neutrons and some binding energy. Two neutrons do not continue the reaction because they are lost or absorbed by a uranium-238 atom. However, one neutron does collide with an atom of uranium-235, which then fissions and releases two neutrons and some binding energy. Both of those neutrons collide with uranium-235 atoms, each of which fission and release between one and three neutrons, and so on. This causes a nuclear chain reaction. For more on this topic, see Nuclear Fission.

Criticality

In order to detonate an atomic weapon, you need a critical mass of fissionable material. This means you need enough U-235 or Pu-239 to ensure that neutrons released by fission will strike another nucleus, thus producing a chain reaction. The more fissionable material you have, the greater the odds that such an event will occur. Critical mass is defined as the amount of material at which a neutron produced by a fission process will, on average, create another fission event.

The Difference Between the Bombs

Little Boy and Fat Man utilized different elements and completely separate methods of construction in order to function as nuclear weapons. Little Boy detonated due to a fission chain reaction involving the isotope U-235 of uranium, while Fat Man used plutonium’s Pu-239 form.

Little Boy

Little Boy was powered by the uranium isotope U-235 in a process that didn’t come easily to the many Manhattan Project scientists working on the uranium extraction and enrichment process. Most uranium found naturally in the world exists as uranium-238, leaving only 0.7% of naturally existing uranium as the U-235 isotope. When a neutron bombards U-238, the isotope often captures the neutron to become U-239, failing to fission, and thus failing to instigate a chain reaction that would detonate a bomb. The first challenge of the project was thus to determine the most efficient way to separate and purify uranium-235 from the overly-abundant uranium-238 - standard methods of separation could not be used due to the strong chemical similarity between the two isotopes. In order to avoid wasting time on one new method that could later prove insufficient to produce enough U-235 to allow the atomic bomb to reach critical mass, General Leslie Groves consulted with lead scientists of the project and agreed to investigate simultaneously four separate methods of separating and purifying the uranium-235: gaseous diffusion, centrifuge, electromagnetic separation and liquid thermal diffusion.

Once enough U-235 was obtained to power the bomb, Little Boy was constructed using a gun-type design that fired one amount of U-235 at another to combine the two masses. This combination created a critical mass that set off a fission chain reaction to eventually detonate the bomb. The two masses of U-235 had to combine with one another quickly enough to avoid the spontaneous fission of the atoms, which would cause the bomb to fizzle, and thus fail to explode.

Fat Man

Powered by plutonium, Fat Man could not use the same gun-type design that allowed Little Boy to explode effectively - the form of plutonium collected from the nuclear reactors at Hanford, WA for the bomb would not allow for this strategy. The Hanford plutonium emerged from the reactors less pure than the initial plutonium extracted from Ernest O. Lawrence’s Berkeley Lab, instead containing traces of isotope plutonium-240, as opposed to the desired plutonium-239. Plutonium-240’s higher fission rate would cause the atoms to undergo spontaneous fission before the gun-type design could bring two masses of plutonium together, which would lower the energy involved in the actual detonation of the bomb.

Thus, a new design was required. Physicist Seth Neddermeyer at Los Alamos constructed a design for the plutonium bomb that used conventional explosives around a central plutonium mass to quickly squeeze and consolidate the plutonium, increasing the pressure and density of the substance. An increased density allowed the plutonium to reach its critical mass, firing neutrons and allowing the fission chain reaction to proceed. To detonate the bomb, the explosives were ignited, releasing a shock wave that compressed the inner plutonium and led to its explosion.

Jay Shelton - Geography and Science of the Atomic Bomb (Part 1 of 7)

My nine-year-old is obsessed with atoms and that has extended to questions about what happens when you split them, how does it cause an explosion and can atoms be split in space? What are atoms?

Before talking about what happens when you break an atom apart, it would help to understand what an atom is and what they are made of. Atoms are extremely small objects that make up everything around us, they are the basic building blocks for all matter.

Every atom has a nucleus at its centre. The nucleus is made up of two things, neutrons and protons. Neutrons have no charge and protons have positive charges. Together neutrons and protons are called nucleons. These are the main parts we focus on when talking about splitting atoms but atoms also have electrons. Electrons have negative charges and they are not found inside the nucleus, they circle around it.

What happens when you split an atom?

There is a certain amount of energy involved in keeping all the nucleons together in the nucleus. This is called the binding energy. If we put the right strain on the nucleus, the binding energy is not great enough to keep everything together and the nucleus splits.

To split an atom a neutron, travelling at just the right speed, is shot at the nucleus. Under the right conditions the nucleus splits into two pieces and energy is released. This process is called nuclear fission.

The energy released in splitting just one atom is miniscule. However, when the nucleus is split under the right conditions, some stray neutrons are also released and these can then go on to split more atoms, releasing more energy and more neutrons, causing a chain reaction.

This chain reaction very rapidly multiplies the amount of atoms split and the amount of energy released. Under the right conditions a large amount of energy can be released within a fraction of a second resulting in a nuclear explosion.

Can every atom be split like this?

In theory every atom can be split in this way, but in reality size matters. The smaller the nucleus, the more energy required to split the atom. Atoms with larger nuclei can be more successfully split

in this way.

Iron is a very stable element. Atoms with nuclei larger than those of iron are generally considered big enough for nuclear fission in this way. In reality, only a few elements are actually used, Uranium is the most common one used in nuclear reactors.

Splitting in two

When the atom is split it does not split into two exact halves; uranium, for example, has 92 protons in its nucleus. An atom of uranium typically splits into an atom of krypton (36 protons) and an atom of barium (56 protons). This is called binary fission. On rare occasions atoms can be split in three, it is called ternary fission.

What about splitting an atom in space?

NASA has already created a nuclear reactor that can operate in space. This small, compact reactor is said to be able to create enough energy (10 kilowatts of electricity) to power several average households continuously for 10 years.

Split The Atom

Although not yet tested in space, this kind of power system has been developed to allow us to travel farther into space, well beyond our current explorations to the Moon.