Related Terms. Ratio of the density of a substance at 20Â°C or 68Â°F to the density of water at 4Â°C or 39.2Â°F.
Nuclear fission. NUCLEAR FISSION. Nuclear fission is a reaction in which an atom's nucleus is broken apart, releasing a tremendous amount of energy. Nuclear fission is used in many power plants on Earth (and is used in atomic weapons). nuclear fission: Reaction that splits nuclei into less massive fragments.nuclear fusion: Reaction that joins the nuclei of atoms to form more massive nuclei. - (n.). The splitting of an atomic nucleus into two large fragments. nuclear fusion - (n.) ... ~ reactors naturally produce free neutron s; their role is to sustain the energy-producing chain reaction.
In order for fission to produce energy, the total binding energy of the resulting elements must be less negative (higher energy) than that of the starting element. Fission is a form of nuclear transmutation because the resulting fragments are not the same element as the original atom.uclear fission produces energy for nuclear power and drives the explosion of nuclear weapons. Both uses are possible because certain substances called nuclear fuels undergo fission when struck by fission neutrons, and in turn emit neutrons when they break apart.