Nuclear Fission For Kids! Trivia Quiz

Answer: The nucleus of an atom changes into two smaller ones

Nuclear fission is the process in which the nucleus of an atom splits into two smaller nuclei, usually of roughly the same size. The emission of an electron from a nucleus is called beta decay; the emission of an alpha particle is called alpha decay; the combination of two nuclei to form a larger one is called nuclear fusion.

Answer: Fissionable isotope

Atoms which can undergo spontaneous fission are described as fissionable. The combination of neutrons and protons in its nucleus is unstable, making it tend to split into smaller pieces to become more stable. This usually results in the release of a significant amount of energy, which is what makes the process so useful.

Answer: Absorption of a neutron by the nucleus

When a fissile nucleus (one which can be made to undergo fission through neutron capture) is hit by a neutron and captures it, the resulting nucleus is thought to be just too large for the nuclear forces that hold the nucleus together (despite the electrostatic forces pushing the protons away from each other) to be effective.

As a result, the nucleus breaks into two smaller pieces for which nuclear attraction can once again overcome electrostatic repulsion. The exact products cannot be predicted definitively, but they will usually be slightly unequal in size, and both about half the mass of the original nucleus.

Answer: Total number of protons and neutrons in the nucleus

The nucleus of almost every atom contains a mixture of protons and neutrons. The number of protons, called its atomic number, determines the element name; the total of neutrons and protons gives its mass (often inaccurately called its weight). Hydrogen-1 is the only atom without neutrons - it has a single proton in its nucleus. All atoms with more than one proton need neutrons to provide the nuclear attraction forces that hold the nucleus together even though the protons are repelling each other because they have the same electric charge.

Answer: Plutonium-239

The other three atoms are too small for fission, although they are all radioactive, and have their uses. When plutonium-239 absorbs a neutron, it becomes an atom of plutonium-240, which can then break into two smaller pieces. Instead of having 94 protons and 145 neutrons, it has 94 protons and 146 neutrons, which rearrange themselves to form two smaller atomic nuclei.

Answer: Three neutrons

Looking at the mass numbers of the reactant (236) and the products (92 and 141), we can see that a mass of 3 is not accounted for, even though all the protons of the original nucleus are in place. This means that there are also 3 neutrons, as well as a number of other products, including a lot of energy.

Answer: Chain reaction

A chain reaction describes the situation in which there are enough atoms near each other that the neutrons released from each fission event can trigger more. The possibility of a fission chain reaction was first suggested by the Hungarian physicist Leo Szilard, who, along with the Italian physicist Enrico Fermi, set up the first controlled chain reaction in Chicago Pile 1, a reactor built in a rackets court (some sources say squash court) at the University of Chicago on 2 December 1942.

Answer: Critical mass

If there is less than a critical mass of fissile material present, the neutrons that are emitted will not find targets to hit and initiate further fissions, so there cannot be any chain reaction. The actual value of the critical mass depends on the nature of the isotope, the actual shape of the material, and its surroundings.

Answer: Moderators

The neutrons produced from fission are usually moving very quickly, because they have a lot of energy, and may move through the fissile material and escape without any further collisions. When the neutrons collide with the carbon atoms in the graphite, they are slowed down, and reflect back moving more slowly than before, making it more likely that they will collide with another fissile nucleus.

The moderator in Chicago Pile 1 was graphite, which is still used for about 20% of nuclear reactors. The rest mostly use water as a moderator.

Answer: Cloning body parts

Nuclear fission releases large amounts of energy, which can be used to heat water and run turbines which can then move a ship through the water or run an electric generator. They also can be set up to optimise the production of various isotopes in the reaction products, which may be used for treating cancer.

Nuclear fission is also, sadly, used to create immensely powerful and destructive weapons.