Posted on 12/15/2010 5:23:20 PM PST by smokingfrog
For the first time in history, a change will be made to the atomic weights of some elements listed on the Periodic table of the chemical elements posted on walls of chemistry classrooms and on the inside covers of chemistry textbooks worldwide.
The new table, outlined in a report released this month, will express atomic weights of 10 elements - hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine and thallium - in a new manner that will reflect more accurately how these elements are found in nature.
"For more than a century and a half, many were taught to use standard atomic weights — a single value — found on the inside cover of chemistry textbooks and on the periodic table of the elements. As technology improved, we have discovered that the numbers on our chart are not as static as we have previously believed," says Dr. Michael Wieser, an associate professor at the University of Calgary, who serves as secretary of the International Union of Pure and Applied Chemistry's (IUPAC) Commission on Isotopic Abundances and Atomic Weights. This organization oversees the evaluation and dissemination of atomic-weight values.
Modern analytical techniques can measure the atomic weight of many elements precisely, and these small variations in an element's atomic weight are important in research and industry. For example, precise measurements of the abundances of isotopes of carbon can be used to determine purity and source of food, such as vanilla and honey. Isotopic measurements of nitrogen, chlorine and other elements are used for tracing pollutants in streams and groundwater. In sports doping investigations, performance-enhancing testosterone can be identified in the human body because the atomic weight of carbon in natural human testosterone is higher than that in pharmaceutical testosterone.
(Excerpt) Read more at eurekalert.org ...
FYI yourself. I’m not taking chemistry over :-)
Thanks, smokingfrog.
So, what they're saying is, the atomic weight of sulfir will STILL be "commonly known" as being pretty damned close to 32.065.
And astronomy...I knew they were going to give Pluto flak in the years ahead.
And Zero....do we need Zero?? They did without it for long time...
With the price of Au going through the roof, they are going to merge it with Pb and do away with alchemy altogether.
Ping. Didn’t see this on FR before.
ping
Do what you want. It means nothing to me.
We could still do without him.
This is extremely important because all chemical reactions are mass-mass reactions.
In stoichiometrics mass is everything.
an atomic mass unit or amu is one twelfth of the mass of an unbound atom of carbon-12
This does not take into account any mass defect inherent in the stability of a nuclei. It also assumes an isotopic mixture which may vary from sample to sample.
Point is, as a physics teacher I've had ongoing battles with Chemistry teachers as to the "proper number of significant digits" to use when computing the molecular weights of elements and compounds. I've opted for which ever one made it an whole number because the five, six or seven digit numbers were not necessarily that accurate.
I win!
Sorry, overly punctilious people annoy me more than progressives (people who think they are always right rarely are).
Thank you!
This is really silly. Yes, some Carbon is Carbon 12, some is Carbon 13, that there exist isotopes doesn’t mean that you can’t calculate the atomic mass of the most common isotope.
Sigh, this is really frustrating.
That's what my ex-wife said about me...especially the zero part.
Zero was invented by the Islamic Arabs btw.
“isotopic mixture which may vary from sample to sample”
Umm no. The definition of the mass of an unbound atom of CARBON 12, assumes just the opposite. That’s why they specify the isotope. This is so the atomic mass of Carbon 12 will remain precisely 12.000 by definition.
Please, don't be punctilious.
What will this mean to the price of Apple stock?
You can say that again...
(and I still won’t know what you’re talking about).
Hey, it was either count Eris in or kick Pluto out.
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