Wednesday, July 12, 2006

So close, and yet so far.

I thought I found an on-line periodic table with ionic radii today. It was really good, yet simple; you click on the element you want, and it gives all sorts of useful facts, including the radii. It even had bonus features, like biological activity and safety information. There was just one problem that I saw.

Samarium. I clicked Samarium just to check a standard, everyday, working class rare earth element. What do I find?
Ionic radius: unknown.
That’s odd. REE ionic radii are probably the best known and most often studied of the trace elements. What would it say this? I read on…

Samarium is most often found in the +2 state, like Europium.

D’oh!

Ladies and gentlemen, here is a tip. There in no point putting up a beautiful, comprehensive, and well-organized webpage if the information it contains is not correct.

Maybe the reason they stated that the Samarium ionic radius is unknown is that they were scouring the literature for the radius of Sm+2. And there aren’t likely to be a whole lot of papers out there containing that data. Eu can be +2. And Ce can be +4. But aside from those two, all Lanthanides are +3 in nature. Including Samarium. And the ionic radius is 1.098 Ǻ.*

* According to this website- http://www.scescape.net/~woods/elements/samarium.html
I don’t have journal access at home. Additionally, I like angstroms, so all of you picometer lovers can shove your SI units into an area of low solar luminosity.

1 comment:

Jose said...

Senor Lemming you have a way with words. You've put together a pretty decent blog here even though most of the things you obsess over don't really concern me. I'd like to land you on some Brain Parades. Let me know if you're interested. You can reach me at jollyspaniard at yahoo do com