Isotope "nuclide", and is still sometimes used in contexts where "nuclide" might be more appropriate, such as nuclear technology and nuclear medicine. An isotope and/or nuclide is specified by the name of the particular element (this indicates the atomic number) followed by a hyphen and the mass number (e.g. helium-3, helium-4, carbon-12, carbon-14, uranium-235 and uranium-239). When a chemical symbol is used, e.g. "C" for carbon, standard notation (now known as "AZE notation" because "A" is the mass number, "Z" the atomic number, and E for element) is to indicate the mass number (number of nucleons) with a superscript at the
Isotope separation nuclear weapons. Plutonium-based weapons use plutonium produced in a nuclear reactor, which must be operated in such a way as to produce plutonium already of suitable isotopic mix or "grade". While different chemical elements can be purified through chemical processes, isotopes of the same element have nearly identical chemical properties, which makes this type of separation impractical, except for separation of deuterium. There are three types of isotope separation techniques: The third type of separation is still experimental; practical separation techniques all depend in some way on the atomic mass. It is therefore generally easier to separate isotopes with a