Talk:Atomic mass unit
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[edit] Dalton as a size unit
In biology, the Dalton is often used in this way: "Only proteins smaller than [...]KDa can pass through this channel/pore." Since it is a unit of mass, isn't this strange? Are mass and size correlated in proteins? Since proteins can fold in many different ways, I would think that some proteins of a certain mass would and others would not fit through a channel/pore. Anyone?
Why did they choose the AMU convention of 1/12 of C12 rather than the origional standard with 1/16 016?
- Probably in large part because that was only the convention of chemists, not physicists who used 1/16 of the naturally occuring mixture of oxygen (or maybe it was vice versa). That's where the first word in the officially recognized name of this unit comes from: unified atomic mass unit, with the symbol u, is the only way this is recognized as "acceptable for use with SI". Gene Nygaard 21:01, 23 September 2005 (UTC)
How come only biological sciences use the Dalton unit? In chemistry there is rarely a unit. The header in a table of molecular weights would be labelled 'mw' or 'molecular weight' with no unit. Just a guess, but it may be because, when talking about large molecular weights, 'kilo (no unit)' sounds kind of stupid.
How do you change Atonic mass into pounds?
- via Kilograms.
I removed the following paragraph; I think it's overly simplistic and illustrates a principle of college algebra rather than of atomic masses. It is certainly not relevant to the amu unit. It also uses the term "relative atomic mass" in a strange way and. AxelBoldt 16:44, 9 Oct 2004 (UTC)
[edit] Using Mass Spectrum Data to Calculate Relative Atomic Mass
A simple calculation may be used to calculate the relative atomic mass of the sample. This is demonstrated in the following example.
| Ion | Relative Mass | Percentage Abundance |
| 11C+ | 11 | 70% |
| 13C+ | 13 | 30% |
Therefore, the relative atomic mass of the Carbon sample is:
- (70/100 x 11) + (30/100 x 13) = 7.7 + 3.9 = 11.6
[this is not the true atomic mass of carbon, it is merely illustrative]
[edit] amu to kg
the number on the page for u didn't agree exactly with the CODATA value referenced at the bottom. CODATA is state of the art, I have changed it to the CODATA value.
[edit] Nucleus or Atom?
Is it 1/12 of a C12 nucleus or atom? I can't remember my high school physics, and some sites say it's "nucleus" and a few say it's "atom".
It's both, the mass of the atom is the mass of the nucleus, since the mass of the electron is negligible. Mchmike 03:19, 19 October 2006 (UTC)
