Atomic Mass Unit
The unified atomic mass unit (symbol: u) or dalton (symbol: Da) is the standard unit that is used for indicating mass on an atomic or molecular scale (atomic mass). It is defined as one twelfth of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of 1.660538921(73)×10−27 kg. One dalton is approximately equal to the mass of one nucleon; an equivalence of saying 1 g mol−1. The CIPM have categorised it as a non-SI unit accepted for use with the SI, and whose value in SI units must be obtained experimentally.
The amu without the "unified" prefix is technically an obsolete unit based on oxygen, which was replaced in 1961. However, some technically sloppy sources still use the "amu" but now define it in the same way as u (based on carbon-12). In this sense, most use of "amu" units today actually refers to unified atomic mass units or u.
Read more about Atomic Mass Unit: History, Terminology, Relationship To SI, Examples
Famous quotes containing the words atomic, mass and/or unit:
“No atomic physicist has to worry, people will always want to kill other people on a mass scale. Sure, he’s got the fridge full of sausages and spring water.”
—William Burroughs (b. 1914)
“It is almost impossible to be a doctor and an honest man, but it is obscenely impossible to be a psychiatrist without at the same time bearing the stamp of the most incontestable madness: that of being unable to resist that old atavistic reflex of the mass of humanity, which makes any man of science who is absorbed by this mass a kind of natural and inborn enemy of all genius.”
—Antonin Artaud (1896–1948)
“During the Suffragette revolt of 1913 I ... [urged] that what was needed was not the vote, but a constitutional amendment enacting that all representative bodies shall consist of women and men in equal numbers, whether elected or nominated or coopted or registered or picked up in the street like a coroner’s jury. In the case of elected bodies the only way of effecting this is by the Coupled Vote. The representative unit must not be a man or a woman but a man and a woman.”
—George Bernard Shaw (1856–1950)