18 May
2009
18 May
'09
2:42 p.m.
On Mon, 18 May 2009, Eric Pettersen wrote:
On May 15, 2009, at 10:40 AM, Tom Goddard wrote:
Hi Armida,
Elaine is right. The atoms are weighted by their mass, carbon counts 12 times more than a hydrogen. Isotopic abundances are not considered -- I think Chimera's atom.element.mass is just the number of protons plus neutrons in the post prevalent isotope.
The mass is the number from the periodic table of the elements -- which is an average across isotopes.
--Eric
More explicitly, the atom's mass is the "standard atomic weight" as given in <http://en.wikipedia.org/wiki/List_of_elements_by_atomic_weight>. - Greg