atomic mass unit(redirected from Atomic Unit)
Also found in: Dictionary, Thesaurus, Medical, Acronyms.
atomic mass unitor
amu,in chemistry and physics, unit defined as exactly 1-12 the mass of an atom of carbon-12, the isotopeisotope
, in chemistry and physics, one of two or more atoms having the same atomic number but differing in atomic weight and mass number. The concept of isotope was introduced by F.
..... Click the link for more information. of carbon with six protons and six neutrons in its nucleus. One amu is equal to approximately 1.66 × 10−24 grams.
Atomic mass unit
An arbitrarily defined unit in terms of which the masses of individual atoms are expressed. One atomic mass unit is defined as exactly of the mass of an atom of the nuclide 12C, the predominant isotope of carbon. The unit, also known as the dalton, is often abbreviated amu, and is designated by the symbol u. The relative atomic mass of a chemical element is the average mass of its atoms expressed in atomic mass units.