Dalton (unit)

Standard unit of mass for atomic-scale entities

The dalton (symbol: Da), or unified atomic mass unit (symbol: u), is a unit of mass defined as ⁠1/12⁠ of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. The word "unified" emphasizes that the definition was jointly accepted by physics (IUPAP) and chemistry (IUPAC) organizations. The atomic mass constant, denoted mu, is an atomic-scale reference mass, defined identically, but it is not a unit of mass.

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