[constant thinker]

I was actually thinking about that when I saw the video. Toss one of the ampules in and dissapear.

About Cs melting in your palm, I'll add that it would be in a sealed glass ampule.

[pantone159]

About Cs melting in your palm, I'll add that it would be in a sealed glass ampule.

Most certainly!  I haven't even been brave enough to do that, I keep the ampule inside another glass vial.
It does melt nicely when I leave home for a few days and leave the a/c off, which is definitely cool.

BTW - There is *NO* way to use 'half of the ampule'.  You open it, you use it.

I have pretty much all the elements, at least the ones that are obtainable.  (I.e. no pieces of Ac or anything  )

[Borek]

oh pretty sweet dude, how many do you have and which is the rarest?

Check out Periodic table on the left menu - Jdurg is one of our Admins.

[jdurg]

One thing to remember about cesium and rubidium is that their melting points are so low, that as soon as they even begin to react they liquify which boosts the reaction rate a great deal.  They are also denser than water so they will sink to the bottom of whatever water container you put them in.  I have seen 2-gram samples of Rb and Cs dropped into a very large clear beaker of water.  (It was a demonstration of the alkali metals on laserdisc that I watched in high school).  The beaker itself was shattered by the explosion right at the bottom as that is where the Rb came to rest.  For the Cs, the top half of the beaker actually blew apart as the Cs liquified as soon as the ampoule was opened.  As a result, it all reacted by the time it went halfway down to the bottom.  In reality, the difference in reaction rate between Cs and Rb is next to nothing.  The only real difference that could be noticed is due to the physical state of the metal itself.  I think a LOT of people get all amped and hyped up over those two metals because they aren't ones you usually see in your high-school/college demonstrations.

[constant thinker]

Ahhh good 'ol laserdiscs. Those things are big. My school still uses them.

I saw my first alkali metal + water reactions on a laserdisc.

[Borek]

Jdurg was correct, and looks like my doubts were not unfounded as well.

http://www.guardian.co.uk/life/badscience/story/0,,1821144,00.html

[wereworm73]

All other factors being the same, would using cesium powder make a significantly bigger explosion?  Even though cesium liquifies quickly in the reaction, I would think the extra surface area of the powdered form would initially give the explosion a stronger kick.

[Borek]

All other factors being the same, would using cesium powder make a significantly bigger explosion?  Even though cesium liquifies quickly in the reaction, I would think the extra surface area of the powdered form would initially give the explosion a stronger kick.

No - it has density greater then water, it sinks and there is no chance for hydrogen to get ignited.

[jdurg]

In addition, the very low melting point of cesium really prevents it from forming a powder.  The cesium itself actually liquifies before it even gets down to the bottom.  If your container is shallow enough, it will cause an explosion towards the top half of the reaction vessel as the cesium spreads out its surface area and reacts with the water at the surface.  If your vessel is too deep, however, you'll just wind up making a VERY caustic solution and wasting a lot of cesium.

This is true for virtually all of the alkali metals.  If you take some sodium and put it in a testtube, then immerse this testtube completely underwater, trapping the Na at the bottom of a large column of water, it will sit there and fizz giving off H2 gas but it won't explode.  I've taken over an ounce of sodium, trapped it under paper towels and taped it to a rock then threw it in a lake.  You saw a few bubbles of H2 gas coming to the surface, but no explosion.

[jdurg]

If you head over to Theodore Gray's website he has an article there about the Brainiac lies and then went and made his own videos of five-gram samples of the alkali metals in water.  As one would expect, the explosions of the cesium and rubidium weren't nearly as massive as the Brain(less)iac show wanted you to think.  Theo also shows how cesium is kind of overrated as an alkali metal in water.  It reacts so damned quickly and with so much heat that there isn't enough time for hydrogen gas to really build up and give you a giant 'KABOOM'.  In addition, the high molecular mass means that for a given weight of alkali metal you don't get as much hydrogen from the heavier ones as you do the lighter ones. 

As you go down the group, the molecular mass increases and the heat of the reaction increases as well.  Five grams of lithium will produce a LOT of hydrogen, but it does so quite slowly and without generating enough heat to light it.  Therefore it doesn't build up in any appreciable amount and it won't ignite so no KABOOM!.  With cesium, it generates a great deal of heat but it generates hydrogen so quickly that it can't build up because as soon as it is made it goes BOOM.  Rubidium generates a very good explosion because it generates a good deal of heat and a good deal of hydrogen, but not so quickly that it quickly dissipates and doesn't explode.  Rubidium will certainly make an explosion.  It's sodium and potassium that are the best metals for making gigantic explosions since they react slowly enough to build up a rich hydrogen atmosphere that then ignites.  (And in that regard sodium is the best since potassium tends to ignite the hydrogen immediately).