# atomic mass unit

(redirected from Atomic Unit)
Also found in: Dictionary, Thesaurus, Medical, Acronyms.
Related to Atomic Unit: atomic mass unit

or

## 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.
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.

## atomic mass unit

[ə′täm·ik ′mas ′yü·nət]
(physics)
An arbitrarily defined unit in terms of which the masses of individual atoms are expressed; the standard is the unit of mass equal to one-twelfth the mass of the carbon atom, having as nucleus the isotope with mass number 12. Abbreviated amu. Also known as dalton.

## atomic mass unit

a unit of mass used to express atomic and molecular weights that is equal to one twelfth of the mass of an atom of carbon-12. It is equivalent to 1.66 × 10--27 kg
References in periodicals archive ?
Rydberg atomic units h = 2[mu] = 1 are used in all plots; the tunneling energies correspond to 0 < k < [square root of 7], corresponding to a barrier height [V.sub.0] = 7 (the maximum tunneling wave number [square root of 7] is shown by a vertical grey line in the plots).
On 3 June 1955, he started to control the UK radio time signals using atomic units of time derived from the atomic clock, effectively marking what he called "the death of the astronomical second and the birth of atomic time".
That's the idea behind Atomic Design--allowing designers and developers to break things down into their "atomic units" and assemble the building blocks into larger components until a complete design system is created, says Frost.

Site: Follow: Share:
Open / Close