atomic mass unit

noun

Physics.

1. Also called dalton. a unit of mass, equal to 1/12 (0.0833) the mass of the carbon-12 atom and used to express the mass of atomic and subatomic particles.

2. (formerly) a unit of mass, equal to 1/16 (0.0625) the mass of an oxygen atom having atomic mass 16. amu, AMU

atomic mass unit

noun

1. amu. Also called: unified atomic mass unit.  dalton. 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

atomic mass unit

1. A unit of mass equal to 1/12 the mass of an atom of the most common isotope of carbon (carbon 12), which is assigned a mass of 12 and has a value of 1.660 × 10 ^{- 24} grams. A hydrogen atom has a mass of 1 atomic mass unit since its mass is 1/12 the mass of carbon 12.

2. Also called dalton

Word History and Origins

Origin of atomic mass unit¹

First recorded in 1950–55