Skip to comments.Atomic weights of 10 elements on periodic table about to make an historic change
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 :-)
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.
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.
Sorry, overly punctilious people annoy me more than progressives (people who think they are always right rarely are).
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.
Thanks. I was weighing some hydrogen the other day and noticed a discrepancy. Thought my scale might be off.
The AP store will make money because all chemistry students will have to download a new periodic table of the elements for their iPhones.
I was trying to explain to my nephew what makes an element an element.
I told him that it comes down to this: the proton number is the decider.
That is why H+ could be either a Hydrogen ion or a proton.
It is Hydrogen because it lost its electron and has only one proton, it is a proton because a proton is a proton.
For example, sulfur is commonly known to have a standard atomic weight of 32.065. However, its actual atomic weight can be anywhere between 32.059 and 32.076, depending on where the element is found.
So, what they’re saying is, the atomic weight of sulfir will STILL be “commonly known” as being pretty damned close to 32.065.
No, the atomic weight for sulfur still be “commonly known” 32 no one cares past that.
Or change the definition of the word “planet.”
Presumably the weights will remain the same. The tables can be changed, though.
I KNEW there was a reason not to pay attention the first time. Now that they’ve changed it, I can learn it fresh—with no preconceived ideas.
There is a method to my madness.
I don't know. Ask him:
“Zero was invented by the Islamic Arabs btw.”
The HECK it was. The only thing the Islamic Arabs invented was beheadings
The Zero was invented by South Indians. Aryabhatta, is generally considered the “Father of Place Value” but the Zero was probably in place well before it.
No we don’t need Zero. We should impeach the Zero!
Is that why Zero keeps adding zeros to my tax bill?
.....Is MO on an ATOMIC OBESITY crusade now too?
Also the value of pi will henceforth be 3.333.
Sure! I told that to my “Chem 300” Prof one time when he dinged a solution to a problem on one of his exams.
It was stll -10 when I walk out of his office. :>)
I know just enough about chemistry to be dangerous. Probably moreso to myself than others. :)
It’s like somebody got a new scale for Christmas and is now out to correct the world.
A major research institution (MRI) has recently announced the discovery of the heaviest chemical element yet known to science. The new element has been tentatively named Governmentium. Governmentium has 1 neutron, 12 assistant neutrons, 75 deputy neutrons, and 224 assistant deputy neutrons, giving it an atomic mass of 312. These 312 particles are held together by forces called morons, which are surrounded by vast quantities of lepton-like particles called peons. Since governmentium has no electrons, it is inert. However, it can be detected as it impedes every reaction with which it comes into contact. A minute amount of governmentium causes one reaction to take over four days to complete when it would normally take less than a second. Governmentium has a normal half-life of three years; it does not decay, but instead undergoes a reorganization in which a portion of the assistant neutrons and deputy neutrons exchange places. In fact, governmentium's mass will actually increase over time, since each reorganization will cause some morons to become neutrons, forming isodopes.
This characteristic of moron-promotion leads some scientists to speculate that governmentium is formed whenever morons reach a certain quantity in concentration. This hypothetical quantity is referred to as Critical Morass.
I guess we’ll now have a “living” Periodic Table...
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.Thanks allmost for the ping! Before clicking in I thought this was going to be related to something else that was recently discovered, but it isn't! Thanks also to smokingfrog for the topic.
How much is earmarked for this change?
I had to take chemistry in college, but, it turned out ok because I could check out all the stuff I needed to make a very high quality still and the nerdy chem lab assistant hadn’t a clue.
Well, for starters human testosterone has carbon-14 in it, while that made from petroleum has had millions of years during which it has all decayed. (This is how “carbon dating” works.) Furthermore, there is a natural isotopic abundance of C-13, about 1% of naturally-occurring carbon is this. But the ratios aren’t exactly the same everywhere, and it’s entirely possible that C-13 is more abundant in human bodies than it is in oil. It wouldn’t have to be much more to be detectably more.
But when you weigh out carbon in, say, sodium carbonate, it’s a mixture, and so you should calculate it based on the relative abundance of the two isotopes in your carbonate sample. Except that this ratio varies by source, which is the entire point of the whole exercise. What the exact masses of the pure isotopes is (1) is already known and (2) isn’t what is being changed here.
Guess somebody has found a way to sell a few extra periodical table charts during 2011.
“Isotopic MIXTURE” M-I-X-T-U-R-E ... meaning... more than one pure isotope.
It’s a ratio.
Actually you should be doing the opposite. The chemical reactions permit you to calculate the relative isotope mixture in the sodium carbonate.