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.
Flare ... Fission. In nuclear physics, the splitting of the atomic nucleus of a heavy element, resulting in the emission of nuclear energy and possibly causing a chain reaction (with similar results) within a mass of the element.Fission, Nuclear ... is a splitting of something into two parts. ~ may refer to:*In physics, nuclear ~ is a process where a large atomic nucleus is split into two smaller particles.... and other physical processes. In popular culture ...
An isotope of uranium with three fewer neutrons, 235 U, can much more readily be split apart than can 238 U; such an isotope is called fissile. When uranium splits (undergoes fission) it releases three neutrons that collide with other uranium atoms, thus creating a chain reaction. Some isotopes can be split too readily, so fast that a continuous fission reaction canât be maintained.