Atomic weights of 10 elements on periodic table about to make an historic change

Eureka Alert ^ | 15 Dec 2010 | Leanne Yohemas

[smokingfrog]

FYI

[IrishCatholic]

FYI yourself. I’m not taking chemistry over :-)

[grey_whiskers]

Like, *PING*, dudes and dude-ettes.

Thanks, smokingfrog.

[WayneS]

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.

[Sacajaweau]

I knew they were going to do this some day...And that's why I dropped out of chemistry.

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...

[monkeyshine]

With the price of Au going through the roof, they are going to merge it with Pb and do away with alchemy altogether.

[allmost]

Ping. Didn’t see this on FR before.

[sionnsar]

ping

[katana]

And Zero....do we need Zero?? They did without it for long time...

Do what you want. It means nothing to me.

[sionnsar]

And Zero....do we need Zero?? They did without it for long time...

We could still do without him.

[Mikey_1962]

This is extremely important because all chemical reactions are mass-mass reactions.

In stoichiometrics mass is everything.

[tubebender]

My only experience with chemistry came in the spiffy little kit I got one Christmas many many years ago but this statement jumped out at me... the atomic weight of carbon in natural human testosterone is higher than that in pharmaceutical testosterone.

[Aevery_Freeman]

Vindicated! The mass of elements on the periodic table are based on a unit defined as:

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).

[BenKenobi]

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.

[Mikey_1962]

And Zero....do we need Zero?? They did without it for long time...

That's what my ex-wife said about me...especially the zero part.

Zero was invented by the Islamic Arabs btw.

[BenKenobi]

“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.

[Aevery_Freeman]

My point exactly, it is an arbitrary unit.

Please, don't be punctilious.

[Leo Farnsworth]

What will this mean to the price of Apple stock?

[smokingfrog]

You can say that again...

(and I still won’t know what you’re talking about).

[Raymann]

Hey, it was either count Eris in or kick Pluto out.