Since atoms are very small their mass is not expressed in gram (e.g. the mass of a carbon atom having 6 protons, 6 neutrons and 6 electrons is 1.992x10-23 g . A relative scale is used where the carbon 12 isotope (6 protons, 6 neutrons, 6 electrons) has been assigned the value of 12.000 atomic mass units (amu). Thus, 1 amu = 1.6605x10-24 g.

a mass unit equal to exactly one-twelfth the mass of a carbon-12 atom.

Protons and neutrons each weigh about one atomic mass unit. The atomic mass unit is defined as exactly 1/12th the mass of a carbon-12 atom, or 1.66057 x 10 -24 g. Atomic mass units allow for determination of relative atomic masses of atoms for different elements.

the unit of mass appropriate to the nucleus of an atom, equivalent to 1/12 of the mass of the carbon nucleus.

Convenient unit for measuring the mass of an atom or molecule: 1 atomic mass unit is defined as I /12 the atomic mass of the most abundant carbon isotope, 12C. A=12 for 12C.

Standard unit that corresponds to one twelfth of the mass of the carbon isotope 12C6 (= 1.6604 x 10-24 g).

A relative mass unit based on the atomic weight of carbon 12, which is taken to be 12; the atomic mass of hydrogen is 1.008 amu. The atomic mass unit (amu) is 1.660 -27 kg.

unit of mass for expressing masses of atoms or molecules

the weight of one proton or neutron.

Chemical: one-sixteenth of the mean mass of an oxygen atom. Physical: one-twelfth of the mass of an atom of the most common isotope of carbon. The atomic mass unit is approximately the mass of a hydrogen atom, 1.67 X 10-27 kg.

1 amu is equal to one twelfth of the mass of a carbon-12 atom.

One-twelfth the mass of a neutral atom of C-12. (1 AMU = 1.66E-24 g)

one twelfth of the arbitrary mass assigned to carbon 12. It is equal 1.6604 x 10 24 gm.

AMU) 1 AMU is equal to the mass of one-twelfth of a carbon-12 atom. Weighing Atoms: Atomic Mass Units[] [ Click "BackButton" for previous location

(amu,u) amu; dalton. A unit of mass equal to 1/12 the mass of a carbon-12 nucleus, which is 1.660 538 73 ¡¿ 10-27 kg ¡3/4 0.000 000 13 ¡¿ 10-27 kg [1998 CODATA values]. Abbreviated as amu or . Sometimes called the dalton, after John Dalton, architect of the first modern atomic theory.

crystalline solid half-reaction mass proton triple point

A unit of mass measurement for small particles.

Unit of mass defined by the convention that the atom 12 C has a mass of exactly 12 u; the mass of 1 u is 1.67 ´ 10-27 kg.

A unit for expressing atomic weights and other small masses; it equals, exactly, 1/12 the mass of the carbon 12 nuclide.

One atomic mass unit (amu or u) is defined as 1/12 the mass of the standard carbon-12 isotope, or 1.66 × 10-27 kg.

The unified atomic mass unit (u), or Dalton (Da), is a small unit of mass used to express atomic and molecular masses. It is defined to be one twelfth of the mass of an unbound atom of the carbon-12 nuclide, at rest and in its ground state.