出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/08/01 19:12 UTC 版)
The unified atomic mass unit (symbol: u) or dalton (symbol: Da) is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound 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 proton or one neutron. The CIPM have categorised it as a "non-SI unit whose values in SI units must be obtained experimentally".