Inspired by the What is Palladium used for? thread, I wondered: what is the most useless or least used element? I add the qualifier that it has to be obtainable in gram quantities, and stable enough to exist for a meaningful period of time. So technetium or promethium are allowable but francium is not.
I would venture to say Rubidium. It is highly reactive and is not (to my knowledge) used in lasers. Seems kinda worthless unless you atom-smash it into Strontium.
I will contribute a fun interactive periodic table for folks to play with–er, to assist them in making their selection.
http://www.chemicalelements.com/
I think I will choose–radon, because although it is one of the “noble gases”, all it seems to be used for nowadays is to scare people into buying radon detectors.
Einsteinium there ar no uses for this element! It is the most useless element.
I don’t know about you guys, but I can’t remember the last time I knowingly used Tantalum.
Damn! Having worked a lot with the alkali metals, I was going to say Francium! Then you disqualified it at the start!
How about something like Praesodymium? Aside from stoichiometric lasers and the odd eramic, I dont know of anything it’s good for.
Is carbon used for anything?
You can navigate through the uses on http://www.webelements.com and they list a LOT of strange uses. Unfortunately, that site seems to be slowed to an utter crawl at the moment (too many people from here looking for useless elements?).
To give you an example, I thought of praseodymium, too, and find this curious fact:
What is so all-fired unique about the requirements for cigarette lighters that you will use an alloy of a rare earth metal to make them?
I think we should disallow elements which don’t occur naturally on the Earth’s surface, useful or not, perhaps disallow all radioactive elements. BTW, the OP said “available in gram quantities”, and I have my doubts that you could obtain a gram of Einsteinium, even should you want to.
Radon is used, BTW, in earthquake detection, and for some forms of radiotherapy.
Happy hunting.
More specifically, the misch metal alloy is pyrophoric and is used in the flints.
Some guy tried to tell me that pencils use carbon to write. Everyone knows they lead.
Astatine. It’s only got a half-life of 8.3 hours. There’s only a tiny amount of it in existence on the earth at any time. What can you do with it?
Isn’t plutonium useless? It’s not like we really use our nuclear arsenal… 
Misch metal, used in making cigarette lighters, contains about 5% praseodymium metal. The rare-earth oxides, including Pr2O3 are among the most refractory substances known. Along with other rare earths, it is widely used as a core material for carbon arcs used by the motion picture industry for studio lighting and projection. Salts of praseodymium are used to color glasses and enamels; when mixed with certain other materials, praseodymium produces an intense and unusually clean yellow color in glass. Didymium glass, of which praseodymium is a component, is a colorant for welders goggles.
Oxygen scares me.
Are you referring to the element, or the Oprah Winfrey TV network?
Apparently, some people have a bizzare sexual fetish for it. Google turns up thousands of hits for “carbon dating.”
I vote for Mendeleevium. It tastes good, but you wake up with such a headache the next morning.
-Loopus
(I’m going to have to stop drinking from unmarked beakers in chem lab.)
It’s perfectly -natural- and -harmless-, man! Just because I like Carbon-play here and there doesn’t mean I’m bizarre…
-Ashley
[sub]I like carbon–DEAL WITH IT![/sub]
“Stupid carbon rod! It’s all just a popularity contest!”
My old job included the filthy, awkward task of scraping praseodymium-containing ash out of an expensive, unreliable and scientifically dubious device called a Weather-O-Meter. Yeah, useful stuff.
As for tantalum, you better not tell Ed Anger it’s useless! It’s been used a lot for making medical implants, including plates that are implanted in people’s heads when they lose part of their skull, like Ed did in Korea.
I never had much use for strontium, myself.