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 ...
OK. If you will go with the flow for a few minutes I will also. One step at a time.
What does your chart say for the atomic mass of Chlorine?
Mine has both. :)
Old school.
34.987
I assume your table gives 35.453 since that is what you have been quoting.
Now (from wikipedia):
“Chlorine has a wide range of isotopes. The two stable isotopes are 35Cl (75.77%) and 37Cl (24.23%). Together they give chlorine an atomic weight of 35.4527 g/mol.”
thus if your ‘old’ table gives 35.453 it is giving the ELEMENTAL mass which is based on the ratio of isotopes.
That must be incorrect. Earlier you stated it was 35.453.
Wikipedia is God.
For the relative mass yes.
The atomic mass is different. You asked me what it stated for the atomic mass.
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 writer of this press release got it wrong. The doc got it right. It's just the periodic table of the elements.
Me too. I noticed a tank truck of hydrogen going up hill just a wee bit faster.
Misplaced and factually incorrect didacticism is ill becoming, and in this case, even libelous.
The father of Zero was an Islamic Muslim, as was a good part of that family.
His stepfather was also Muslim.
Islamic Muslims are indeed responsible for Zero; Indians had nothing to do with him.
Sir/Madam,
You have wronged me!
I said “The Zero” and not just plain “Zero”.
As we all know.. our current President is not even the original or the best Zero.
So, THE Zero, still stands proud and non Islamic.
:)
Good point.
I thought he was "invented" by an African Arab.
“The atomic mass of CL 35 is 35.453 as a result of CL 35 having 17 protons and 18 neutrons”
“CL 35 the 35 means that it has 17 protons and 18 neutrons. Why isn’t this 35.000 instead of 35.453? Because the mass of the neutron is the combined mass of a proton plus an electron. That’s where you get the extra bit on.”
How far away do any other bodies need to be in order for the body in question to be considered to have “cleared the heighborhood around its orbit”?
I’m curious, because it makes me wonder how they can judge Earth to have “cleared the neighborhood around its orbit” when it has this ‘moon’ thing following it around everywhere.
How did you standardize the acid solutions (i.e. how do you know what their molarities are)?
There’s 4 variables.
Concentration X, Concentration Y, Crystal Z and Crystal W
Adding concentration X to Z and W gives me two equations:
X+Z -> XZ
X+W -> XW
Adding concentration Y to Z and W gives me two more equations:
Y+Z -> YZ
Y+W -> YW.
I can then use the systems of equations to solve for all 4 variables, once I know the concentration of acid required to dissolve YW and YW. To keep it easier, I make sure I have the exact same amount of both Z and W, and I keep the concentration in the standard solution the same. The only thing that will change between the two is the volume of the acid.
How did you standardize the acid solutions (i.e. how do you know what their molarities are)?
Obviously you didn’t bother reading my answer or you’d already know. Bye.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.