21 Feb 2005

Paul R. Potts

So, I decided to order a couple of pounds of pure bismuth to melt down with my son, in order to attempt to create bismuth crystals. In case we can’t get any visible crystals, I also bid on a really pretty specimen on eBay. We might also see whether crystallization can be improved by using a “seed” crystal. I don’t know whether that works with metals or not.

I mentioned cesium as being another metal that would melt in your hand. Well, some web sites describe a couple of other metal elements as being liquid at “room temperature,” but really it depends on the temperature of your room. Cesium melts at about 83 degrees Fahrenheit, gallium at 86, and rubidium at 102.

It is a bit odd to talk about the “melting point of francium,” since it is an unstable radioactive element that would be insanely difficult or insanely dangerous to accumulate in a quantity large enough to be visible, but the melting point of francium, presumably calculated via mathematical modeling rather than by observation, is listed in the books as 27 degrees Celsius (about 81 degrees Fahrenheit). Bromine and mercury are both liquid at what I think of as comfortable “room temperature” – around 70 degrees Fahrenheit.

So, this is technically true – cesium will melt in your hand, but I should probably also point out that when it was done melting in your hand, it would then melt your hand, or, rather, burn its way through it in an extremely painful way. Cesium is extremely hazardous, and pure cesium must be kept under glass in argon. A cesium FAQ list at the University of Rochester says:

“Cesium is an alkali metal, in the same group as lithium, sodium, potassium, and rubidium, and is similarly reactive, but to a much higher degree due to its extreme electropositivity. It reacts explosively with water, and with ice down to -116 C. In air, it catches fire spontaneously and burns with a brilliant sky-blue flame…

Its hydroxide is the most powerful aqueous base known, and will eat through glass, flesh, bone, and numerous other substances.”


The FAQ is here:


This is too bad, because it is very pretty; if mercury is quicksilver, cesium could be called quickgold. It would be a beautiful specimen to have in an element collection, but it is far too dangerous to have a specimen, even a nicely ampouled specimen, in the house with small children (or even with me; I would no doubt want to handle it all the time too). Oh, well.

Of possibly more interest are the non-toxic metals with low melting points. More on those when we get our bismuth!

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