Talk:Atomic mass
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[edit] ISOTOPE DISTRIBUTION (EXTRATERRESTRIAL)
A good example of heterogeneous isotope distribution is Carbon-14 (which is radioactive). Each object in the solar system has a (more or less) steady-state concentration of carbon-14, but since C14 is radioactive, it is generally replenished by solar neutron radiation bombardment and transmutation of atmospheric nitrogen(14). For example, if venus and earth had the same amount of nitrogen, then venus would have more C14 - since the neutron flux at venusian orbital radius is higher. Of course, given similar neutron flux, C14 generation depends on the concentration of atmospheric nitrogen.
Deuterium is known to be more prevalent farther out in the solar system (though it's not entirely known why). Between solar systems, the common isotope ratios are fairly close to within each other, but our data are limited. Presumably isotope ratios between different generation of stars are different, and who knows about different galaxies. Isotopic fractionation in planets is also known, which may contribute to abberations in the isotope ratio.
Ultimately, this means that the average molar mass of a particular compound is dependent on where you are (although the differences are likely to be minute).
isotope ratios in exobiology helium is particularly bad isotopic analysis for understanding origin of terrestrial impact debris
[edit] The unit
What is the unit you messure here u or g/mol?Stone 08:39, 24 February 2006 (UTC)
- The atomic mass itself is just that, a dimension of mass. Technically you could use any unit of mass you like. The unified atomic mass unit (u), and grams per mole (g/mol) are two equivalent ways of expressing one and the same scale based upon the carbon-12 atom, respectively 12 g of carbon and the number of atoms therein. Femto 12:41, 25 February 2006 (UTC)
[edit] History
Nothing in the article to indicate when the concept of atomic mass / atomic weight first developed. -- Jmabel | Talk 06:53, 30 March 2006 (UTC)
[edit] Definition
"The atomic mass of a chemical element (also known as the relative atomic mass or average atomic mass or atomic weight) is the average atomic mass of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance." This is a horrendous example of circular logic. To simplify the sentence it says: "The atomic mass, aka the average atomic mass, is the average atomic mass. Even worse is that is goes on to contradict itself. First it says that the atomic mass is the average atomic mass (all isotopes abundance averaged) and then continues to speak about the atomic mass of individual isotopes. I have reworked the beginning of the definition to fix these issues and given external links to the IUPAC definitions as reference. --134.9.228.11 00:35, 4 April 2006 (UTC)
The IUPAC and NIST definitions of "relative atomic mass" do not appear do agree. Could somebody clear this up?--63.145.1.170 15:15, 21 September 2007 (UTC)
[edit] Too technical
15-Oct-2007: This article had been tagged "too technical" on 11-Dec-2006. To help simplify the technical presentation, I have added a diagram of a lithium atom, counting the protons, neutrons and electrons. Beyond that diagram, please list specifics, below, about why the article is too technical. I am removing the {technical}-tag at top, which did not simplify this article during the past 11 months. -Wikid77 09:45, 15 October 2007 (UTC)
