OPEN THREAD 20200206

Basically, all legal free speech is allowed. We will assist the authorities in dealing with illegal speech. You are each other’s moderators. Have fun. And don’t forget to MAGA at nuclear levels.

Citizen U

Day 92 – URANIUM.

25 thoughts on “OPEN THREAD 20200206

  1. Uranium may be an actinide, but it is FAR from dull.

    The story begins with a mineral that was once called “blende,” from a German word for “to blind” because it resembled galena, a valuable ore of lead, yet contained nothing of value. It is now regarded as a zinc ore, but back then it wasn’t appreciated for that. Today, blende is called “sphalerite.”

    One variety of blende was called pitchblende, for being black, like pitch. This showed up alongside silver, lead and copper ores in Germany and what is now Czechia (the Czech Republic).

    In particular, there was a town called Joachimsthal in what is now Czechia, with a VERY rich silver mine, and that mine had pitchblende in it.

    Joachimsthal had so much silver its lord began coining very large silver coins, which became known as Joachimsthalers, which got shortened (in some countries) to thalers. These are the direct ancestor of the US dollar.

    But we’re more interested in the pitchblende tonight.

    The German chemist Martin Heinrich Klaproth (1743-1817) took an interest in pitchblende, and began experimenting on it. He eventually ended up, in 1789, with a yellowish substance, which he figured had to be the oxide of a new metal. (This sounds a lot like the stories of discovering the lanthanides, doesn’t it?). (This oxide, by the way, is now known as yellowcake.)

    There was, at the time, a strong tradition of associating metals with planets. (Look, for instance, at mercury, and Mercury.) And in 1781, just eight years before, a new planet–the first one since ancient times–had been discovered. So Klaproth named his new metal, which he hadn’t isolated, after the planet: uranium. (Nor was this the only time this happened: shortly after Ceres was discovered in 1801, cerium was named after it. Eventually we realized Ceres was something of a totally new type, an asteroid, not a full-blown planet.)

    OK, so Klaproth wanted to see the real metal, not just its oxide. He tried a trick that often worked, he reacted it with charcoal. That often pulls oxygen away from something else. And indeed he got a shiny black powder, and he figured that was the metal uranium. So did everyone else.

    In fact, yellowcake is UO3 uranium trioxide, and what Klaproth had done was to strip one oxygen from it; his black shiny powder was uranium dioxide, UO2.

    This was eventually realized, in 1841, by the French chemist Eugene Peligot (1811-1890), who had been experimenting with UO2, and finding he couldn’t get things to add up; he concluded there must still be oxygen in it. He then decided to try to isolate the real metal. He started with uranium tetrachloride (that sounds like nasty stuff), UCl4, and figured he’d try something a lot more reactive than charcoal to pull the chlorine away.

    He used potassium metal. (Yikes!) And did so without injuring himself. And now he had a new black powder, and this really was uranium.

    Nobody but a few chemists cared. Uranium was a thoroughly useless substance, unremarkable in any way, most people had never even heard of it. It was as obscure back then, as thulium is today.

    When people tried to determine uranium’s atomic weight in the middle of the 19th century, they thought it was about 116. So it didn’t even get noticed as having the highest atomic weight of any known element. Instead, it was thought to lie between silver and tin. The champion was bismuth, coming in at 209.

    Dmitri Mendeleev, when he constructed the first periodic table around 1869, found that uranium simply didn’t fit, chemically, between silver and tin, not in the least. But it worked well if he doubled the weight to 232; then it naturally fell into a place with the right chemical properties. Going back to the experimental data, it could actually be re-interpreted to give a value near 240; someone had made assumptions while interpreting the data the first time around, that apparently were unwarranted.

    That brings us up to 1871. Uranium is now by far the heaviest atom known, easily beating out bismuth…but that meant nothing to anyone but chemists and trivia geeks like Cthulhu and me.

    To be continued…

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    1. Nice detour into the Czech Republic. I like to point out that Germany’s push to annex the Sudetenland on the eve of WWII was essentially seizing all the natural defenses and mines, while temporarily leaving the hop and barley fields alone.

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  2. In 1896, something interesting happened. The previous year, X rays had been discovered by Wilhelm Konrad Roentgen, and exotic rays became all the rage. Well, Antoine Henri Becquerel was running experiments to see if fluroescent minerals emitted X rays. He used photographic plates, wrapped in black paper. Visible light couldn’t affect them, but X rays, if any were present, would. So he figured he’d put the fluorescent substance on top of the plate, expose it to sunlight, let it fluoresce, and then later, unwrap the plate and develop it. If it were fogged, the fluorescent substance had emitted X rays.

    He tried a huge number of fluorescent substances, and got zero positive results. There was one exception: potassium uranyl sulfate. It would fog the plates. So Becquerel got excited. That particular day it had been cloudy, but he’d wait for good weather, really expose the potassium uranyl sulfate, and get a really good fogging of the photographic plate.

    So what happened? Murphy stepped in. Paris had a long run of crappy weather. Becquerel had a bunch of brand new plates and nothing to do with them, for a while, so he stuck them in a drawer, and put his sample in with them.

    Days passed; Becquerel got more and more frustrated. He was this close to confirming an interesting result from his experiment; if only the damn Sun would come out!

    Well, he figured, he might as well develop the plates. Maybe there had been some lingering X ray fluorescence. That could be interesting, couldn’t it?

    The plates were totally fogged. As if he had simply exposed them to sunlight! WTF!!!

    Whatever this was…it could go right through the black paper, and did NOT need the Sun to excite the sample, like fluorescence did. It just kept on going, even in the darkness of his cabinet.

    Becquerel tried samples that hadn’t seen sunlight in months. He eventually realized that what mattered was how much uranium was present; he even tried uranium compounds that did not fluoresce.

    Whatever this was, it had NOTHING to do with fluorescence, and everything to do with uranium.

    He had a new phenomenon, and it became known as Becquerel rays. Maybe it wasn’t Murphy after all.

    Marie Sklodowska Curie stepped in almost immediately, and named this new phenomenon “radioactivity” and showed that thorium, which had been discovered in the meantime and had an atomic weight almost has high as uranium’s, was also radioactive.

    This, suddenly, made uranium glamorous. Nothing like this had ever been seen before…a totally inanimate lump of metal, just pumping out energy continuously.

    Further experimentation showed that uranium and thorium were giving off gamma rays…a lot like X rays only even more energetic. But they were also giving off small particles with mass, and that implied atoms weren’t the smallest pieces of matter out there. So now we had “subatomic particles.”

    And it turned out uranium and thorium slowly turned into lead. (The alchemists who had tried to turn lead into gold would surely be spinning in their graves; something was turning other things into lead–the wrong direction!)

    Ernest Rutherford was able to demonstrate that an atom had a huge cloud of negatively charged particles (electrons) and a very small, dense nucleus with a positive charge to balance the electrons.

    And in 1913 Henry Gwyn-Jeffries Mosely used X-rays to excite nuclei, and showed that every nucleus had a positive charge that was a multiple of hydrogen’s; this became the atomic number. Hydrogen is 1, iron is 26, silver is 47, tin is 50, gold is 79, lead is 82, bismuth is 83, thorium is 90, and uranium is 92.

    Uranium had the highest number, and nothing known lay between bismuth and thorium. It was speculated that there probably were elements 84-89, but they hadn’t lasted long enough to survive to the present day, whereas thorium and uranium had known half lives of billions of years, so they were still around. This is essentially correct.

    So now uranium is fascinating–it was radioactive, the highest atomic weight, the highest atomic number…but still, only chemists really cared.

    To be continued.

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  3. Uranium minerals were tested for their radioactivity. And there was too much of it. Chemists knew exactly how much uranium was in the mineral. And they knew, based on uranium’s 4.5 billion year half life, how much radioactivity there SHOULD be from that much uranium. Yet there was quite a bit more. Separating out the uranium and checking it, the numbers came out right; the more pure the uranium, the better the fit. So there was other stuff in the minerals that was radioactive. More radioactive than uranium.

    Which made no sense; if it were MORE radioactive, it should have been gone by now.

    They even noticed the pure uranium samples got more radioactive with time.

    This was realized well before 1913.

    The only explanation that made sense was that the uranium didn’t turn directly to lead, it broke down by stages into intermediate elements, and an old sample would basically be in a balance, uranium decaying into something else at a rate just enough to replenish that something else as it decayed into yet another something else. If it’s something that breaks down quickly, there’s never much around. It’d be undetectable chemically.

    Well Marie Curie and her husband Pierre realized they could find those in-between elements, though, because their radioactivity was a beacon.

    So they got a bunch of pitchblende and started experimenting on it. (The Ronco Pitchblendeamatic had not been invented yet.) They went through several tons of the stuff, doing experiments and noticing if any of the results showed a concentration of radioactivity. Eventually, in 1898 they got just a bit of polonium (84). Further experimenting hit on radium (88). But they couldn’t get much of it, and they wanted a visible sample. So they asked Joachimstal to send them their waste slag, which they were happy to do as long as the Curies paid the shipping.

    They went through tons of it to get the radium. By 1902 they had a tenth of a gram. And it became the glamour substance. Who cared about uranium any more?

    Back to 1911 and Ernest Rutherford. He decided to try to deliberately produce nuclear reactions. He was able to bounce alpha rays off of nitrogen atoms…and some of them transformed into oxygen atoms.

    He decided to try other things, and, ultimately, switched to using bare protons (which are just hydrogen atoms with the electron stripped away, or to put that another way, positive hydrogen ions). Devices that could accelerate protons were developed, in particular by Ernest Orlando Lawrence in 1931. Still, it was hard to do this, because the proton, with a positive charge, was repelled by the nucleus, which was its target.

    But it also turned out that when beryllium was exposed to alpha rays, a new particle came out. One without a charge. That made it hard to pin down, but eventually it was to become known as the neutron (1932). It was much easier to hit a nucleus with a neutron, because the positive charge of the nucleus didn’t repel it, as it did with protons and alpha rays.

    Almost immediately, we realized nuclei didn’t just contain protons, they also contained neutrons.

    And often, when a neutron was added to a nucleus, the nucleus would become radioactive, spit out an electron, and one of the neutrons would turn into a proton–the atom would become an atom of the next higher element.

    What would happen if you did this to uranium? Would you get element 93?

    This would be a new–and man-made–element. That would be a big deal!

    To be continued.

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  4. Enrico Fermi, who had worked a lot of this out (including methods to slow down neutrons so they could react with nuclei), decided, in 1934, to try. He got some very peculiar results. He was unwilling to announce success, he couldn’t be sure what he had. But Mussolini got wind of this and insisted on announcing a triumph of Italian physics.

    By 1940 people had untangled the mess and realized that Fermi hadn’t just created element 93, but that element 93 had decayed *again* and become element 94. These elements were named neptunium and plutonium, continuing with the planet sequence.

    But elsewhere, Otto Hahn and Lise Meitner whad different ideas. Perhaps, if they hit uranium atoms, they could get TWO alpha decays instead of just one…uranium could turn directly into radium without going through thorium first.

    They tried it, figuring if they started with pure uranium, then later detected radium, they’d have the proof they needed. But there wouldn’t be much of it. But, radium and barium are virtual twins, like zirconium and hafnium. So they figured they could do the bombardment, mix the uranium with barium, chemically separate the two, and see if the barium was radioactive…because it had some radium in it. Then they could put the final period on the whole thing by separating the radium from the barium, which was difficult but possible.

    Before they could get started, Germany annexed Austria, and Meitner fled to Denmark, where Niels Bohr helped her get on her feet again.

    Hahn, who had stayed behind, performed the experiment, and indeed the barium was radioactive. But he couldn’t get any radium out of it! Not a shred!

    Eventually, the logic forced itself on him. If he couldn’t separate out the radioactive atoms from the barium by any means, it’s because they were barium.

    So wait…you hit uranium, element 92, with a neutron…and you don’t get something nearby (like element 93 or 91 or 90 or even 88), you get barium, element 56?

    This implied…that the nucleus was splitting into two very large pieces. It was fissioning!

    Meitner had been kept updated, and although Hahn didn’t want to go public–this was just too crazy–she did. This was January, 1939. World War II was months away.

    As it turned out: Fermi’s results came from hitting the uranium-238 isotope, with 92 neutrons and 146 neutrons.

    Hahn and Meitner’s results came from hitting ther uranium-235 isotope, with 92 neutrons and 143 neutrons. And it turned out the fission released two or three free neutrons. Another physicist, Leo Szilard, had already wondered if one could find a reaction, started by a neutron, that would release more neutrons, and set up a chain reaction and produce energy…and now here was his answer.

    American physicists were the first to follow up on this…luckily for the world.

    And Leo Szilard, who had fled to America to get out from under Hitler, realized we HAD to do that chain reaction before Hitler did. He wrote letters to scientists, begging them to keep their research secret…and many of them did. And he eventually got Einstein to write to Roosevelt, and the Manhattan Project was born.

    to be continued:

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  5. But let us consider uranium 235. It has a half life of 700 million years or so, which means most of the U-235 the earth had at formation, is gone. And indeed uranium is less than one percent U-235, 0.72% in fact.

    If you add a neutron to uranium 235, it becomes U-236. U-236 is likely to just split into two large pieces, as Hahn had discovered. (All uranium isotopes can do this; but U-236 does so often, and very quickly, when it has just been excited by the neutron capture that created it) This releases a LOT of energy. It also happens to release some neutrons…which could go on to hit more U-235, which releases more neutrons…the chain reaction has started.

    That means that U-235 is not just fissionable (all uranium isotopes *can* fission) but since it can sustain a chain reaction, it’s “fissile.”

    The rub is, there’s so little U-235 in a lump of uranium those freed-up neutrons are more likely by far to hit a U-238 nucleus, and do other interesting things…but not release more neutrons. That would squelch the chain reaction right there. Instead we need to have a net increase of neutrons (for a bomb) or a steady number of them (for a reactor).

    The only way to do that with U-235 is to concentrate it. Somehow, it must be separated from the U-238.

    This cannot be done chemically. Both types of uranium are uranium and will behave the same. But, because the weight is over one percent different, perhaps, say, a centrifuge, or gravity could separate them. But for that to work, the uranium cannot be in solid form.

    It turns out that uranium hexafluoride is a gas, and (bonus) there’s only one isotope of fluorine found in nature, so any difference between uranium hexaflurode molecules is due to the uranium atom. So the Manhattan project was able to produce “enriched” uranium this way. It was difficult (fluorine is nasty, nasty, nasty stuff) and took buildings so big people rode bicycles in them to do, but we managed to produce uranium where a large fraction of the U-238 had been removed.

    You end up with some uranium that is enriched (a large percentage is U-235) whereas the U-238 that has been removed is called “depleted uranium”

    [And, if you hear about Iran and its centrifuges, that’s what they’re for: to enrich uranium, to make bombs.]

    Apparently, uranium that is more than 5% but less than 20% U-235 is suitable for use in reactors, above that you’re getting into nuclear bomb territory.

    In principle, it’s easy at this point. To make it go kaboom, you need only put a sufficient mass together in one place at one time. That mass is the critical mass. But that depends on how concentrated it is. The more concentrated, the better. You could make a bomb out of hundreds of kilos of 25% U-235, but if you can get it up to 85%, you need a lot less.

    It’s so simple, that we didn’t bother to test the U-235 bomb we built in World War II. (We did test the plutonium bomb, near Alamogordo, New Mexico. But that’s a story for another day, like maybe two days from now.) We dropped our one and only U-235 bomb on Hiroshima, and it worked like a champ.

    The bomb, named “Little Boy,” consisted of a cylindrical slug, and a cylindrical ring, of U-235, combined mass 64 kilograms, of 80% U-235. There was a neutron reflector around the whole thing, increasing its efficiency; the 64 kilograms was about two and a half critical masses.

    To detonate it, explosives fired behind the ring, it went down rails to surround the cylinder, and the critical mass was formed. With a little help from some neutron sources in the nose of the bomb……


    (Note to potential aggressors: Don’t sneak-attack US soil. Unless some pusbag like Obola is in office. Little Boy was ~20 kilotons. We now have bombs, in the plural, at least 50 times as powerful.)

    So the U-235 bomb is very simple to make…but getting the U-235 itself is a very painful process.

    The U-238 isn’t useless for nuclear energy…but it has to go through a different process, again, a story for a different day.

    Liked by 2 people

  6. So the Pope is having a conversation with Aliens….

    Pope: “Do you know Jesus?”

    Alien: “Oh, yeah, Jesus. Great guy. He comes to our planet twice every year.”

    Pope: “Every year?! It’s about two millennia and we’re still waiting for his second coming.”

    Alien: “Maybe he didn’t like your chocolate.”

    Pope: “Chocolate?”

    Alien: “Every time he visits, we gather the very best chocolate from each manufacturing plant on our planet and give it to him before he leaves. Why, what did you do the first time he came here?”

    Liked by 3 people

  7. Second musical interlude. Ddanna likes music from movies, so let’s go with this.

    The Henry Wood Promenade Concerts — better known as the BBC Proms — is an eight-week summer session of orchestral works culminating with a Last Night. Top-notch orchestras from throughout Britain generally play over the course of the event.

    In keeping with my desire to give a different perspective of things, it should be noted that the camera generally features the electric bassist during electric guitar parts…..and he looks completely bored.

    Liked by 1 person

  8. Two aliens landed in the West Texas desert near an abandoned gas station. They approached one of the gas pumps, and one of the aliens addressed it, “Greetings, Earthling.

    We come in peace. Take us to your leader.” The gas pump, of course, didn’t respond. The alien repeated the greeting. There was no response. The alien, annoyed by what he perceived to be the gas pump’s haughty attitude, drew his ray gun, and said impatiently, “Greetings, Earthling.

    We come in peace. How dare you ignore us in this way! Take us to your leader, or I’ll fire!” The other alien shouted to his comrade “No, you don’t want to make him mad!” But before he finished his warning, the first alien fired.

    There was a huge explosion that blew both of them 200 meters into the desert, where t hey landed in a heap. When they finally regained consciousness, the one who fired turned to the other one and said, “What a ferocious creature. It damn near killed us!

    How did you know it was so dangerous?” The other alien answered, “If there’s one thing I’ve learned during my travels through the galaxy…any guy who can wrap his di#k around himself twice and then stick it in his own ear, is someone you shouldn’t mess with!”

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  9. Uranium is the 51st element in order of abundance in the Earth’s crust, and is about 40 times more abundant than silver. Uranium is more plentiful than antimony, tin, cadmium, mercury, or silver, and it is about as abundant as arsenic or molybdenum.

    Various plants, bacteria, and fungi are found to interact and concentrate Uranium.

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