For the Chemists

[marki]

This going to cause a little grief for my students.

http://www.iupac.org/web/nt/2010-12-13_2009-atomic-weights

Full technical report here

http://iupac.org/publications/pac/asap/PAC-REP-10-09-14/

Been a busy year for the IUPAC people, they are about to redefine hydrogen bonding as well.

Mark

[CraigS]

Hmm..

This is a bit like renaming Pluto as a dwarf planet.

Did they take a vote on it ? (Perhaps everyone agreed so .. no need).



Cheers

[marki]

I am still trying to get over the changing of the periodic table from 8 groups to 18 groups. I have to correct myself all the time when discussing trends with my students, must be getting old


Mark

[CraigS]

Here's another one for the chemists (and others) …

The old standard for the kilogram is about to be superceded …

Au revoir, kilogram

The atmosphere was different because a major change is afoot: the cylinder may soon be removed and dethroned.

For 121 years this cylinder has ruled over an international network of masses and scales that stretches from laboratories in national and local metrology offices into everyday life in the form of grocery stores, post offices and home scales. The cylinder is both a thing and an institution. And its days are numbered.

The CIPM's draft resolution must still be debated by the CGPM at its 24th meeting in October next year. But two technologies appear on the verge of satisfying criteria for implementation, and the CGPM is expected to take steps towards a revision. "It's a significant step," says Wallard. "It would provide, for the first time, an anchoring of all the base units of SI to fundamental constants, from which we can build up the whole system."

Soon, farewell to the one kilogram cylinder !!
Adios !



Cheers

[OICURMT]

I think we should follow the KISS principle... list the weight as the LOWEST possible stable form of an element. Any other configurations of an element which result in a higher weight than the base element get a new symbol attached above the primary... enclosed is an example for Boron...


maybe we can think of something similar for the planets, dwarfs, asteroids, comets and fine particle dust...

[renormalised (Carl)]

That's what I call nitpicking. Yes, an element will have a varying atomic weight due to the difference which occur between isotopes of that element, but the basal element (i.e. C12, O16, N14) have a precise weight and are the ones that are used in chemistry. All they're doing here is saying "Oh, if you're going to do this and that, you'll need to use the precise isotope weight for the situation". Carbon, whether it's C12, 13 or 14, will still react chemically in the same manner, it's just that certain isotopes are favoured in various reactions due to their mass...lighter isotopes are easier to remove, energywise, than heavier ones.

Splitting the periodic table up into more groups than is necessary is just a waste of time. It's not being more precise, it's just being pendantic.

[marki]

Originally Posted by renormalised

Splitting the periodic table up into more groups than is necessary is just a waste of time. It's not being more precise, it's just being pendantic.

My thoughts exactly Carl.

Mark