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How Not to Do It

Mental Health Break: The Alkali Metals Show Their Personalities

Some blogs run pictures of cats to give the readers a break from the ordinary. Around here, I thought that this might be appropriate. Here are the alkali metals, from top to bottom, differentiated in the most basic way possible. No, not by tasting them, sheesh: by tossing them into a dish of water:

(Courtesy of the Open University site in the UK). One thing they don’t go into is the effect of density. Up to potassium, the metals are still light enough to float. But cesium drops like the rock it is, with depth-charge results.
I will consider running a photo of a cat, as long as he’s working up a reaction.

32 comments on “Mental Health Break: The Alkali Metals Show Their Personalities”

  1. Petros says:

    The delights of school chemistry. But I’ve never seen anyone go beyond potassium.
    The mind boggles at what the francium video would have looked like.

  2. SteveM says:

    Hah! It was Cesium-like experiences that got me out of the lab!

  3. milkshake says:

    For the column “Things I Won’t Work With”, maybe you could describe the thrilling properties of liquid K+Na alloy. There was reportedly a large explosion and fire in Oak Ridge few years ago that involved one ton (!) of this silvery goodness. The cleanup must have been quite something.

  4. Hap says:

    From third-hand experience, I can tell you that 70 g of Na/K alloy will heat up a hood quite nicely. The white powdery goodness from the fire extinguisher took about a week to clean up, though some of that was depresssion as much as the intransigence of the residues.

  5. MedChemSF says:

    These guys do Rubidium…haven’t listened to the audio, but the explosions are quite impressive.

  6. John FitzGibbon says:

    That blowed up real good.
    Hope someone gets the SCTV reference

  7. dearieme says:

    It must have been fun working on the Fast Breeder Reactor – liquid sodium coolant, itself cooled with water. A tube leak would be fun.

  8. DavidQ says:

    Stick around to the end and they drop cesium into a bathtub.

  9. SteveM says:

    Re: #6 John Fitzgibbon
    I read a paper about explosions generated by Johnny LaRue when he was a grad student in Professor Sammy Maudlin’s group.
    P.S. He unfortunately withdrew, got an MBA and eventually became a Big Pharma SVP.

  10. Sili says:

    I’m pretty sure the Braniac guys were busted for cheating and using explosives for bathtub. Look for a wire going over the rim. (I think it was on Bad Science.)
    I can has haidruhgeene?

  11. Chemjobber says:

    Speaking of sodium metal, check out this lawsuit (the best part is the “hefty decontamination fee”):
    According to the Charles River Clean Up Boat’s website, on the day of the incident, one of the volunteers retrieved an item which resembled a rough piece of styrofoam. After the object was placed in a trash bin full of wet debris, it began to smoke. Ultimately, the object caused an explosion which resulted in chemical burns to Soisson and Nardin and to three of the paramedics sent to treat them. State Police chemists later identified it as a block of sodium metal.
    Hefty decontamination fees for the Boat also threatened the future of the nonprofit, but MIT made a donation of $6,000.

  12. David P says:

    Ah, yes. Nothing better than alkali metal and water to make the chemist’s heart sing.
    I will have to dig for it, but I saw some experiments where they compared the set (except francium of course!) and found that potassium gave the best bang for the buck – the higher metals are of course heavier (so not as many moles), which partially explained it. I think they are also SO reactive that the reaction is over too quickly to be truly enjoyed as a spectacle.

  13. David P says:

    Here it is:
    Opening paragraph:
    “So far as I am aware, history does not record whether the great chemist Sir Humphrey Davy, who discovered sodium in 1807 by electrolysis of molten sodium hydroxide, ever threw any in a lake. But I think it’s safe to say that very few chemists since then haven’t.”

  14. Steve says:

    The OU site you linked to has some more great videos. Since you like to work with obnoxiously dangerous things, I assume you’ll be freshly preparing any AlBr3 you need in future. I particularly like the description ‘Once the reaction gets going, it quickly takes on the appearance of the pit of hell’!

  15. CMCguy says:

    What memories this brings back. In grad school we used to set aside the cut-off Na scale and then on occasion conduct midnight forays (between work-ups) to a fountain across courtyard from the labs for dance demos/disposal exercises. Young and foolish looking back but was a good diversion from being in the lab 12-14h/day.

  16. Wavefunction says:

    Now repeat after me; Cesium is God. Cesium is God.

  17. mitch says:

    @MedChemSF People always link to the Brainiac video, but it should be noted they faked it.

  18. Chris says:

    I’m sure I remember Geoff Wilkinson writing somewhere that he thought he was one of the few people to witness the reaction of sodium (or potassium – can’t remember which) with aqua regia….

  19. daen says:

    Ah, yes, school chemistry. When I was an 11 year old taking chemistry classes I remember being told that, for the purpose of doing these kinds of demonstrations, our chemistry teacher had a budget of one disposable glass bath and one disposable 11 year old chemistry student …

  20. SteveM says:

    Re: #20 daen “one disposable 11 year old chemistry student …”
    Too bad it’s now 43 year Ph.D. Chemists who are disposable…

  21. Like several others said, I’ve never seen past K. All the demonstrations were fun to watch, but the Cs was spectacular. Seeing all of them in succession really puts into perspective the reactivity as a function of position on the Periodic Table. Thanks for sharing.

  22. Heather says:

    Hi Derek,
    Long time reader, first time commenter! I had a “mad chemistry teacher” in highschool who would do that series every year. It was great fun, and the one day you could be guaranteed everyone (even students not taking the course) would be in the lab!
    Is a series of great, light hearted cheimstry/science videos that have worked great with 6-9th grade kids I’ve shown them to. And they can all be done at home…

  23. Notsoblue says:

    Reminds me of the excellent “Look Around You”
    The episode on Sulphur is brilliant:

  24. skatesailor says:

    Odium for Sodium
    A teacher deficient and placid
    Mixed alkali metal with acid.
    The big balls of sodium
    Blew his off the podium,
    And left him half-acid and flaccid.

  25. A Nonny Mouse says:

    Our mad Welsh chemistry teacher did aluminium iodide- fortunately in the one fumehood that we had. Needs Al powder mixed with iodine and a drop of washing-up liquid (don’t ask me why…). Wait a while for things to start happening…..
    Also, it was said that our old lab technician used to dispose of crusted sticks of sodium over Blackfriars bridge in London.

  26. Bored says:

    On the first day of class in 11th grade chemistry, our teacher walked in, and without saying a word, dropped a chunk of sodium into a lab sink about half-filled with water. After the resulting explosion and geyser, and after everyone stopped laughing and screaming, he said, “Be careful in here.”

  27. Rather than cats, my mental health days involve all the second-hand high-performance military aircraft I worked on at NASA Dryden. Shock diamonds are infinitely more interesting than even the cutest kitten.
    I’ve just started reading your blog and I’ve already had to buy two books. My dog isn’t interested in quantum mechanics (or in high-performance military aircraft; he sleeps through sonic booms) but I loved Emmy and her pursuit of cheese bunnies and anti-bunnies. Thanks for the recommendation.

  28. Hey! I know this is kinda off topic but I was wondering if you knew where I could find a captcha plugin for my comment form? I’m using the same blog platform as yours and I’m having trouble finding one? Thanks a lot!

  29. colin says:

    I love how the video ends right after the Cesium, showing, once again, that it needs very little explanation

  30. Gregg Eshelman says:

    The small piece of sodium was interesting, how it reversed direction on hitting the sides.
    Square tank, a pair of linear slides with pieces of UHMW plastic attached, some string and pulleys = Sodium Pong.

  31. David says:

    My High School Chemistry Teacher: “And that was potassium in water.”
    Me: What would Cesium have looked like?”
    My High School Chemistry Teacher: “Flying glass shards.”
    Me: “And Francium?”
    My High School Chemistry Teacher: “The shards would have been radioactive.”

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