Good. Evening and welcome to the Exploratorium, and, two after dark and this evenings presentation. Of everything, matters tales. From, the periodic, table. I'm your host Ron, hips man and tonight. We, are going to be, talking about a, really, interesting element. Gallium. So we hope that to. Find. This interesting I hope you all have your collectible, card now. You can fill in your set I think's probably outside I, guess, I, didn't, see them but I'm sure outside, we have the other cards, if you happen. To miss the first, 30, everything. Matters tales from the periodic table you can fill in your set two and but, you have to keep coming to it so you get all hundred and eighteen we. Haven't actually produced any more than tonight so I can't. Help you with any more after gallium. So. Try. And go outside and fill, in your whole set we started, at hydrogen and, we're, now up to, gallium. So we hope that you'll come. To more of these. How. Many people, have. Been to after dark before raise, your hand if you've been to after doctor before how, is your first after dark Wow. Well. If you enjoy after dark tonight you, know we have this every Thursday evening and one, of the best deals on the planet, is to I'm going to be commercial here is to become an after dark member, for, like 45, bucks you, can come to 52, after darks, that's. A pretty good deal less than a buck apiece. For. A whole year and you can come on Friday, evenings, during the summer we're open Friday evenings as well so it's a really good deal. We. Hope that you'll take advantage of, that so. Tonight's program, is about, gallium, we're gonna have, two, speakers myself, and we. Have a guest speaker as well the total may be about 60 minutes we'll have some questions and answers at the end I'm. Going to talk about the the. Chemistry. The history the, application. Of gallium, a little bit and for, about 20 minutes I'm gonna be followed by a Sri bounty Chaudhary who, is a professor at UC Davis, and she's going to share with us how these. Technologies. Impact of the world and how she's been involved in actually developing some of these technologies, so, let's. Begin with. Gallium, gallium. We. All are familiar since, you're coming to the period of tales. From the periodic table there's the periodic, table and tonight. Gallium. Is we're gonna go all the way down here in the periodic, table gallium, it's the 31st, element, in the table it's, atomic. Number is 31. And that, just tells you how many protons are, in the nucleus it, doesn't tell you anything about the neutrons just how many protons are in the nucleus if, there's. 31 protons, got to be 31 electrons, and all the chemistry happens, out there and the electrons, so that's, what's important, is that number, right there that if it's 31 protons, its gallium, if you, were here last month if it's 30 protons. Its zinc so, and, all, those elements and the periodic table have unique numbers of protons, but gallium. Is our subject for tonight I want to go not. Too far back but I want to go back to this guy right here Dmitri. Mendeleev and he's the guy that came up with the whole concept of a periodic table he, took some of the properties, of the elements he arranged them into kind of a an order. That seemed logical to him here's the paper from his. 1869. Paper. Let's just magnify that so you can see a little bit look how nice everybody could handwrite back then I always. Am I'm always impressed by that if, we arrange that to make it actually readable, for you there, we go so that's kind of his arrangement, of the. Period, of these periods, of elements, that. Had common, the, rows had common. Properties. And. You'll. Notice if you look carefully here you'll see that there's a few of them there that have kind of question, marks before them these, were elements. That were not known during, the time of, Mendeleev. And he. Kind, of gave them some names you can see them here there. There. This is again more this, is again turning that chart 90, degrees there. And there these were elements. Are not known yet but he, thought that he might be able to predict, what they would be and he gave them some names there they are in kind of the classic arrangement that we're familiar with these are the elements of known at the, time of Mendeleev, and.
These. Unknown, elements. He, called eka. Boram, the. Same column, is boron eka, aluminum. Eka. Silicon, and eka manganese, and these. Turned, out to be elements. That were, eventually discovered, scandium, gallium, for tonight germanium. Which is coming up in October. And technetium. Which is quite far away from us here a couple of year away at least. His. Prediction, of these elements, was quite good let's, just take gallium as an example here. Is kind, of a table. And in. This column here is the what, Mendeleev. Predicted, just, by knowing where they were in the table and here, are the actual property. So you can see he got pretty. Close to the actual properties, here the. First person that actually measured, the density, measured. It wrong and he said go, back and measure that again I think you're gonna find something different and he went back and we measured it and by god it was exactly. What. Mendeleev. Predicted. So. And. The first guy that actually discovered. Gallium. Was this fellow here paul, émile, lecoq de. La, blood drum. Sorry. Have. A hard time with that one let's. Just call him Paul. He. Discovered. In the, spectrum, of some, zinc. Or. A. Line. A color of light being given off by that zinc or that was not zinc, if, you looked at that spectrum, right there there's a it's. Kind of hard to see him the projector here but there's a brighter. Purple. Of a violet, line there, from. An element, that was as yet unknown, and so. This, Paul, discovered. That element, he named it after. His, this. Was discovered spectroscopically, he. Named it since he was a French chemist obviously, he named it after his country. Well. This is the sample that he used to discover, this sample. Of zinc sulfide. Which is a it's, a zinc mineral called spoler right and, he called it Gally after, the, name for France gall and. Which, eventually became, well actually there's an interesting story there because he has word. In his name look Koch which. Means the rooster. The, Latin, for rooster by the way is galas. So. There's some debate about whether he actually named the elements sort of for himself, as well as for his country but he denied that. We. Know about denials, now don't we and, that eventually of course became, gallium. Probably. His press agent had the next day had him walked that back. Gallium. Does. Occur. In a, moderate, concentration. In one. Mineral called, gal ight and. It's. The it's this really. Beautiful mineral. Here but this is three minerals. All in one so. The gal I'd is kind of a silvery, stuff that you see in there but, and though it does occur, in somewhat, high concentrations. This is a very rare mineral, so it's not a good source to actually mine for, gallium because the mineral itself is very rare, gallium. Is mined from, these, two, minerals. Spell, ah right and, bauxite. And you'll notice that you don't see gallium. And either of the formulas, down here it's in there as an impurity but. It's it, makes, up about. Sixteen. Parts, per million in, the Earth's crust and that is actually enough it gets a little bit more concentrated. In these minerals make but it makes it enough to be commercially, feasible, to. Refine, it further once, you've gotten the aluminum, and the zinc from these two minerals. There. The usgs the US Geological, Survey estimates that there's about a million tons of gallium. Contained. In the known reserves of this, bauxite, mineral, and zinc ores so.
There's, A lot of it out there if. You actually it's a it's fairly expensive stuff, as, opposed, to like iron, which. Is pennies. Of for a pound, but gallium. Is about two hundred dollars, a pound so. It's not super, expensive I mean you can go on to to. Amazon. And you, can actually buy gallium, on Amazon, and you know for 20 you can buy that. Much gallium, hundred, hundred grams of gallium or something like that as a matter of fact if you want to feel how dense. This is I'll pass these around. Now. These gallium. Is you'll see here is, -. You can pass down that gallium. Is it's not, a super dense mineral. We'll talk about that in a moment. But, it's like I said it's not, a super, abundant. Element. But it's also not super rare either. If. We look here it's about the 25th. Most abundant, element in the universe so, you, know there's 118, elements so 25th, the abundant is not too, rare. It, makes up about a millionth. Of a percent of, the universe if you look at the Sun you'd expect it to be a little about, the same as the universe because this Sun was made out of the stuff from the universe but, it's actually a little bit more about four times as abundant in the, Sun because. The Sun is actually made from. Material. That was from, older stars, that blew up and so the Sun has concentrated that a little bit so the Sun is kind of a second or third generation star. It's. About the 20th, most abundant, element in meteorites and, the. 23rd. Most abundant. Element in the crust of the earth where we get our our gallium, from and the, 23rd most abundant. Element in the oceans and. In. Humans. It, is. Non-existent. There. Is no gallium, in your body there's. A lot of elements in your body but no gallium, now, as I mentioned it is created, in stars. And gallium, is created only in supernova. Explosions, so, the, fact that there's any gallium, here means that we are made of the. Remnants. Of supernovas. You, and I are made of remnants, of supernovas, that's, kind of cool it's, like the Carl Sagan used to say that we're made of star stuff. Now. I, mentioned. That gallium. Has 31. Protons, in its nucleus but, it can have a variable, number, of neutrons. In the nucleus as. Long as has 31 protons, we, call it gallium, and we. Call those other things with different numbers of neutrons we call them isotope. That comes from word I so the same tokes place, so. It means the same place in the periodic table but they have different weights and. Gallium. Has a lot of isotopes. If. You add up the number of protons plus the number of neutrons that's, this number right here so. There's, 31, isotopes. Of gallium. That, we know of right now and. Of. All of those 31 most. Of them are radioactive there's only two of them that are actually stable. 69. Gallium, 69 gallium, 71, so it's. Have to do this subtraction but, 71. Minus 30 100 I can do that 140. Neutrons. And 30. Forty. And thirty eight neutrons those. Are stable, non, radioactive, all, the rest are radioactive and, of, that, gallium, 69, makes up 60% of. The Nall the natural gallium, on the earth and gallium. 71 makes up about 40%. Of the, gallium. On the earth now I mentioned the rest of them are radioactive. They. Each have last a different amount of time they they sit there and then they decay some. Of the isotopes, sit, around a little longer before they decay and some of them sit around a little less these, are all of the isotopes that last longer than one minute, and. The longest, one you can see here is gallium 67. Which lasts for only three, and. A quarter days which. Means that there's really none, of it none of it on the surface of the earth because it's all decayed, by now but, you, can get gallium by the decay, of other elements higher up in the periodic, table so, it.
Does Exist but it doesn't exist in very high quantities, or, you can make it in reactors. As. Marek gallium 67. Is used, you. Can be injected with this and it goes to places in your body and concentrates, there and then they can they, can detect the radiation, sort of like a bone skin but they use Ekka, manganese. For that bone they use a, technician. An element that's coming up for, that most of the time but gallium, is used in bio. Assays. If. You look at the metal itself you can see it in the test tube but here you can actually see gallium, crystals. They're kind, of real it's kind of a pretty metal. It's, although. They were playing heavy metal when you came in it's not that heavy of a metal. It's. Kind of Midway. Density. Is five by, six grams, per cubic centimeter you, know what water is what's water, one. Right, and they'll, put a few more up here too. You can see here that iron is good. Not a good amount denser, than than gallium so iron is denser lead is a lot denser and, well. Actually let's take a look at it on a chart I love these charts I. Get these from periodic, table com by the way periodic, table calm awesome. Website. Periodic. Table dot-com was done by the guy who did this book Elements, Theater gray awesome. Book, available. In the store. But. I love this book this is a wonderful, book photography. The best photography, of elements I've ever seen. Density. There's there are elements, that are very dense up here and they're elements of course like most of the gases that are very very light. Down. Here and I, have a bunch of things on the stage right here sorry guys I'm moving out of the light here but there's, things, times you're ranging. From maple. To plastic, -, well. I have tungsten is my dentist, element that down there to lead to. Copper. To. Iron, to. Titanium. Whoo. Oops, aluminum. To. Magnesium. And there's, where gallium, Falls so gallium is kind of in the mid mid, range they're a little, lighter than most metals but not. Too light you can you can feel it wherever, the gallium is you can kind of feel its heft there by, all means come on up and after the talk and. Sample. These things be careful, with the tungsten, the tungsten is extremely. Dense and lifting that brick of tungsten and you may think that it's actually stuck, to the stage it's, not, used. Both hands. Don't. Drop it on your foot it will leave a mark. Gallium, is actually really soft stuff. This. Is a table. Of hardnesses. That often, is used for mineral. Mohs scale of hardness where the super soft stuff is one like talc and the super hard stuff like diamond. Is ten and gallium. Is way, at the top there so Galilei it has a very it's very very, soft, you can actually cut it with a knife that's. How soft it is. One. Interesting, feature, of gallium, is its melting, point. If, you look at the melting point of gallium it's, very. Very low compared, to most elements, it's way down, there. So. The only elements, that actually melt at a lower temperature are. Cesium. I have. To go over here and look at it our cesium. Bromine. Which is actually a liquid at room temperature mercury, a liquid at room temperature and the rest are gases so. It's really low low, melting temperature. Don't, do this but if you put gallium in, your. Hand. Gallium. Melts, in your hand at less. Than body temperature so. It'll. If you put a lump of it in your hand it melts, just like M&Ms don't.
However. The interesting thing about gallium, is even though it melts, at a very low temperature it, boils a bed of moderately, high temperature, it's way up there in the you, can see here up in the 2000, degree range so there's a huge range from the melting point to the boiling point that's not true, of most metals the, boiling point of the. Melting. Point are fairly, close together now, I wanted to demonstrate the, the melting. Point of. Gallium. Here, I actually. Have a spoon. Here that, I cast out of gallium. This, is science this is jokes, that scientists, play on each other. Okay. But I'm not gonna play the joke on you I have some hot water down here. And. I want to put some hot water in here. So. Let's get some nice. Hot water. There. We go so. I'm going to take the spoon and let's watch what happens to the spoon as I dip it in can. You see it there. We go. So. If you served, you this spoon with somebody with some really nice hot tea. You. End up with a little puddle of. Gallium. At the bottom, so. I finished. Tonight we will put, that in will actually put, it into some ice water and it'll freeze up into a nice little ingot, and we'll do. It again we'll make a new spoon for it. Okay. Back. To the slides an. Interesting. While another interesting, quality about gallium, if. We go to this slide here you may notice that this. Is a, graph. Of thermal, expansion how. What, portion, of say. I make a rod that's a meter long and I heat it by one degree, Celsius. What. How much longer will it get you'll. Notice that gallium is way. Up, there, aside. From mercury. Which has a super high expansion, rate with temperature. Gallium, is the next one down. For. That it expands quite a bit by the way the fact that mercury is the very top element here makes it really useful in thermometers, you put a mercury, thermometer in your mouth the mercury in the bulb expands, and squeezes, it up the capillary, tube and that's what makes mercury thermometers, very sensitive, gallium. Although, it melts at, body. Temperature makes. That means it's not a real good element, for, thermometers. Is. It. Is possible I'll, talk about a gallium. Thermometer, in a moment but, because, of this. It. Expands, so much it also has another unusual feature and that is, when. You freeze it normally when you make things colder colder colder colder they get smaller smaller smaller smaller by that by that ratio. Water. You notice the water when when water freezes do what happens to water when it freezes it. Doesn't continue to get smaller it expands. Extremely. Unusual, there's not many substances. That do that gallium. Is one, of those substances. When it freezes it gets bigger which means that. When you buy it and you'll notice that those little tubes I passed, around are, made out of plastic and that's, because when you pour it in as a liquid and it freezes as a plastic it gets bigger so if you put it in a glass vial it will shatter the glass vial so. All the bottles. That we put them in are plastic bottles. Now. About, that thermometer, thing, you. Can make alloys, with gallium and this. Is an you, can make an alloy that actually freezes, at about. Minus. 20 degrees, C, or about, minus, 2 degrees F and. You do that by combining gallium. And indium. And. Tin. Gallium. Indium. And. Tin. In chemistry, is usually called as Dennis, or. S. T am so, Dallin Stan metal actually, is, 68. Percent gallium. 21 percent indium and about 10 percent tin, and it, stays liquid down below the freezing point of water you, can make this into a thermometer and you. Can go out and you can actually buy this. Thermometer, and. It's a mercury free, oral thermometer doesn't, have any mercury of course it does have indium.
And Gallium, and. Tin, in it but, they're actually fairly non-toxic. And. So you can actually if you if you insist on having a thermometer that has metal, that. Flows up a capillary tube as opposed to using an alcohol thermometer. Or a digital. Thermometer probably. Much easier the digital thermometer then you actually can still, get one and it's called a gallon. Stan thermometer. Pretty, cool. Okay. I, was. I didn't, really want to go into the applications, yet but let's go back a little bit to the things the gallium. Atom is fairly large compared, to hydrogen we always kind of do this comparison, and. Again. It's spectrum, has that unique. Violet. Line which is kind of hard to see in this slide but it's there and, that's how they identified, it originally, you, can see that. Violet, line in, the solar spectrum now. If I take here's the solar spectrum and there's the there's actually a dark line here it's kind of hard to see again because it's so violent. Down here. But. That's caused by gallium, in the outer atmosphere, of the Sun and. This, is the solar spectrum here, all these dark lines are caused by elements, in the Sun so this really. Broad one here is due, to hydrogen and these, are due to magnesium, and this is due to sodium. Those, two so, these you can tell isn't, it cool that you can tell what the Sun is made of without actually going there and scooping up a cup that's. Pretty cool spectroscopy. Extremely. Extremely. Useful, tool let's. Go do a little app some applications, now gallium. When you combine, it with a couple of elements like arsenic. For instance is useful. In high super high-speed transistors. Little switches and these, switches, are really high speed they can run at billions, they could turn I don't off billions of times per second you have these in your cell phone these, are the. Mesfet. Stands for metal, semiconductor, field effect transistor. And, these, are used in all kinds of microwaves. Circuitry. So, that's one cool application, but I think one of my favorites, of course is. LEDs. Which. Is why I the. Table tonight actually, I'm going to turn these blue LEDs off cuz there may be a little I sort, of turned them off a lot earlier everyone, in the front row cool finally. LEDs. Are come in all colors and I have like here, I did have some beautiful, color LEDs, here can I move this forward if I can move this forward. Maybe. Turn it this way. Look. At across the spectrum red, orange, yellow, green. Blue, there's. A violet. There's actually a blue, and as an ultra violet one there a blinking, LED and this one which has actually three the bottom one there has three, chips in it red, a green and a blue and you can vary them so you can make any color you want here's another sample set, of LEDs. Bigger. Sample. So. You make lots of different colors of LEDs and they all have but you'll notice one thing it's common, among most. Of these LEDs, what's, common. Gallium. Gallium. Is. Present in almost all of, them not all of, them but most of them, 90%. Of them. If. You look at that LEDs are actually a fairly new invention. 1962. Was like the first kind of reddish LED and that was aluminum. Gallium, arsenide. So. Aluminum gallium and arsenic in there excuse. Me for a moment. Much. Better. So 1962. We first had red LEDs and we all remember back alone, some of us may remember back the, very first like calculator, displays had, red LEDs, in them the. Green LEDs, in 1975. Are created, in a couple different ways gallium, phosphide. Gallium and, phosphorus which. Makes kind of a dim ish green. LED, but, if you wanted any brighter they, actually use. Either these are red LED, and they double, the frequency with a little crystal inside there so, a couple different ways you can make green LEDs. And. In, 1972. Yellow. LEDs, gallium. Indium phosphide, or gallium phosphide, again, but. The big invention, the one that really. Allowed. Us to have lots of applications and, the Holy Grail was. The blue LED and, the, blue LED had, to wait till 1990. For indium. Gallium nitride. Or gallium nitride, blue. LEDs, invented. By this. Fellow here. Who. Also worked, with two other fellows too but I'm, only gonna show him four right now he. Has a blue laser also. Basically. Laser, diode, lasers are basically. Semiconductor. LEDs. That can, produce a beam and. He actually him and his two fellow, workers did get the Nobel Prize for the, blue LED. So. Significant, was that invention because the blue LED with the blue LED you could make the, white LED and. That was kind of the Holy Grail how can we make efficient.
Lighting And the, white. LED here is actually, it's, actually a blue LED here's. The blue LED the gallium nitride, blue LED this is the light the blue light coming from the gallium, nitride, and then they put, something, that glows, when it's hit by blue light it, flores's. It's. A phosphor, and it glows, yellow and. So you add yellow to. Blue and you get white so. This is the spectrum of white. LED it's not like, it doesn't look like the spectrum of a regular light bulb I move, these over, so. We use those in a moment. Actually, here's a here. These are blue these. Are white LEDs, right here you, see the yellow phosphors. Those. Phosphorous glow when, they're hit by the blue light they glow yellow and you add together the blue and the yellow and, you get the white, apparently, white light. Which. Gave us finally. Decent. LED, light bulbs much. More efficient, LED. Light bulbs. They're. Very efficient, actually, if we compare them here, I can show you let's. Turn. That on oh that's. Kind of bright so, this. Is a an incandescent, lamp, this. One here is the the. Compact, fluorescent, lamp and here. Is an, LED lamp these are each 40, watt lamps, now. When, I say 40 watt, that's. That's, really only applies to the incandescent, bulb, that's how much power that. Incandescent, bulb is using let's, look at that, well. They all produce about the same amount of light as you can see well this, one doesn't until it warms up a real, disadvantage, of compact, fluorescent, bulbs in my opinion, I'm. Not a big fan of compact, fluorescent, bulbs as you will see. It. Takes a while for them to warm up LEDs. Do not take any time the world neither do incandescent, although. The in conditions put up a lot of heat, they're. Not very efficient, look. At how much power is you I'm gonna turn that off it's too hard to look at. An. Incandescent. Light, bulb uses well, a 40 watt incandescent light bulb not surprisingly. Uses. 40 watts of power but. Look at a compact, fluorescent light only, uses 8.6, watts and an LED only. 7.3. Watts a little bit more efficient these are fairly. Equivalent, efficiency. Wise if, we look at do a division how much light do you get per watt. Incandescent. Bulbs. Well, I kind of suck they. Produce about about five percent of the energy that goes into them goes into light and the night and they're 95 percent if you put your hand over this you'd realize it goes into heat which is, okay if you need to heat your house but.
Generally. Speaking that's not why you put light bulbs in your house not to heat it so, you can see that you get look, at how much more you get sixty four lumens per watt, over. 60 lumens per watt compared. To twelve that's, it that's hugely efficient, and. Then. The lifetime. Incandescent. I, get. I think, I get more use, out of my life incandescent, than this I don't know where this figure came from compact. Fluorescent, was advertised, to us as lasting. To, almost ten times as long as your incandescent but, that of course anybody. Out here believe that no. It's a lie I. Have. Incandescent, bulbs, at home and that are still running from the time I got, my house thirty years ago and I've replaced every, compact, fluorescent, bulb that I've ever installed, but. The LED bulbs, claim, to. Last a lot, longer and, we'll see because we haven't had our we, haven't had them around long enough yet but they, have been lifetime, tested, but, this. Is a lie and, and. They. Have mercury in them they, have toxic. Metals. In them so. Bad. It. Was a stopgap measure but, while we were waiting for LEDs to become more efficient I guess okay that's it's only blessing. If. You could make diodes of every color since. A, weld. Like this laser that I'm using here, and I have others you, can make lasers. This. Is a, barely. Visible violent. Lasers so violet you can barely see it it's actually, it's, actually a lot brighter, than you see here maybe, you have a card here yeah, well looks a little brighter on that card. Or. I have. A well, I have a green laser here but here's a little brighter green laser is. Amazingly, bright or you know you're gonna get lasers, in. Red. And all, different kinds of colors and these are just diodes they're really they're really, LEDs. But they're special, LEDs that have been prepared. To reflect, light back and forth and create laser light by. Amplified. By, stimulated. Emission they, amplify that light different. Lay different talk August. Next, month lasers, full-spectrum, science, will.
Do Some laser work here to. Come. Back for a full spectrum science, next month, lasers. And. Here. You can see you can get if you get LEDs. Of all different colors you can get lasers of all different colors as well. Ceramic laser light shows now they usually have a red laser a green laser and a blue laser and then they combine those you can make any color you want now. This. Is an interesting physics, experiment, the. Sun makes. Energy by combining. Hydrogen. And, creating. Helium, in the center of the Sun but, in. Doing that neutrinos. Ghostly. Particles, that hardly. Interact, with anything at all stream out from the Sun they, don't interact with the Sun you have trillions, of neutrinos passing, through you now every. Second, but. They don't interact with you fortunately. And so, but, - so that means detecting, them is really difficult, to do and one. Way to detect them was to take a very large vat, of something. And then, allow, the neutrinos, to interact, with that and this, is an experiment in well. In. Russia. Called. Sage the, Soviet, American gallium. Experiment. And they. This, has the largest amount of gallium ever gathered in one place it was 50, to 57 tons at varied of gallium. In this experiment, right here down in these vats down here and when. Neutrinos, go through there every, once in a while one would react with a gallium, atom, and change, it into a germanium. Atom. And then. You could separate, I mean this is very difficult experiment - you can separate the germanium out from the gallium. And count. How many neutrinos, interacted. And that gives you an idea of how many neutrinos, are coming from the Sun and, this experiment, discovered real something really interesting they only got 40. Percent of the neutrinos, that they were expecting. To get from the Sun what was the explanation for, this and it has something to do with neutrinos, being able to change their flavors in flight, they oscillate but. Very. Interesting experiment, also had some nice some. Politics, that went along with it because 50. Tons of gallium is worth a lot of money at $200. A pound and. So the and this was the gallium was owned by the Russian government and they needed. To pay some Mineworkers, and they decided they were going to repossess, the gallium from the experiment, and the, scientists didn't want them to do this and they kind of objected. Highly. Vociferously. And the actually Russian, government sent in some. Form of military. Command. To take the gallium away from the scientists but one science has figured out that he could unplugged. All the locks and things like that they couldn't get in and that gave them some time to renegotiate, and they. Were actually able to, renegotiate. The. Gallium. Experiment, and keep it running for another few. Years so. Kind. Of cool that. Scientists. Fight back yeah. One, interesting thing that gallium can do and you have to be very careful, when you hat when you're holding on to gallium and that is it can actually penetrate. Into. The crystal structure, of. Other. Metals like aluminum, this, is normally this is an aluminum lock and it's normally, very strong you would have you could not Brooke bust to open this lock with a hammer no.
Matter How hard you tried you cannot bust this lock open with a hammer but if you. Just take a little drop of gallium, and put. It on to the lock like this the. Gallium, actually goes into the crystal structure between the crystal grains of the, aluminum. And four hours later he, can just take his hand and break. The, lock. Apart. Like that totally. Compromising. It so don't put gallium on, anything that's aluminum, like, laptops. Or things like that because, it will destroy, the. The material. Very very. Destructive. And, but it's really cool the fact that actually, gallium can work its way into that. Far into, that crystalline. Structure of the aluminum in just four hours I think that's I think that's stunning actually. This. Is, something. That is a little familiar to us here at the Exploratorium. Our. Founding. Director Frank Oppenheimer, worked on the Manhattan Project with, his brother J robert Oppenheimer and, this. What you're looking at there is actually, not the real thing but it's a simulated, pit it's, the center, of a plutonium, bomb this is that that is a. Solid. Core. Of plutonium. You see it's about six inches across and. The. Idea inside, of an atomic bomb is you kind of compress this thing and when you compress it it will go critical and and explode. But, the plutonium, cores, the, plutonium, is not a very stable metal and to stabilize plutonium. They mix it with, gallium. Yes. So, gallium, actually, played a part in the very. First atomic bombs, that, pit. Which. Was the, very center of the bomb was actually Frank's. Friend Phil Morrison, who is a kind, of really famous physicist. Too well. Last taught at MIT he, passed away fairly, recently, actually. Carried, that out to, the to the, bomb. On in, the car. It's. Really great when you get physicists, who come here and tell you these kinds of stories that they actually carried a plutonium, pit in, his in the, 57, show knows that 45 Chevy or something like that now, it must've been earlier than that, here. That pit goes in the middle of this this is the device. This. Was the very first plutonium. Bomb that. Was set off at the Trinity site in New Mexico this, guy here is a dr., Bradbury, he was later became the director, of the Los. Alamos labs, and there's a museum in Los. Alamos the city of Los Alamos that you can see all this kind of really interesting history and. The. Nice thing about gallium, when we start talking about the biology of gallium, is that, there is no biology, of gallium, so. It's not a. Has. No biological function, so we can skip it so, I go to a fun thing here what, fun, thing a gallium was used for it was to make the world's, smallest, book. This. Is the world's smallest book, here and, you. Can see here this is a the scale here this line here is 50 microns, long that's 50 millionths. Of a, meter hair. Is. About 20. To 30, microns. So, this, would almost fit, across. The diameter of a hair it's a little bit bigger than a hair we. Can magnify it and you can see it a little, closer these, lines were, etched in silicon, this is. Silicon. So they took, some silicon like this and they cut it into a wafer, well. Here's, a wafer of. Silicon. Except this silicon wafer is actually a solar cell very. Thin. And. Then. They sent. A beam of gallium. Item, atoms, at this, wafer and that's what caused the etching, here and this is really hard to read, but. This is the. Book is let's. See if I can read it here it's called teeny.
Ted. From. Turnip. Town. So. That's the book and you could actually this book cost fifteen thousand, dollars to make by, the way, it's. The smallest book ever made guinness, book of rules records it's. It's. Carved, on it's 30, little pieces of silicon. And. These. Lines here just have. 7. Billionth. Of a meter across that's really small so. Kind, of a cool fact, so. I'm gonna go to a little haiku we're. Coming, up to the end melting. In my hand agent. In nuclear bombs feigning. Innocence. Next. Next. Everything. Matters tales from the periodic table is. Germanium. But we're taking a break so that doesn't happen until october. So, on October the 18th at, 8 will be our next, element. Or I also mentioned, the fact that we're doing lasers, but this month. We, full-spectrum. Science, is about. Heat and temperature, so. Thank, you.
2018-07-26