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- Good day, everyone. And welcome to Everything Matters, Tales from the Periodic Table. This is your host, Ron Hipschman, and we'll be talking today about some really cool stuff in the periodic table. You won't be seeing much of me during the talk because I'm going to be using my Keynote mainly. And so let's just go there and see what we find. Palladium is our element of the day . Palladium is a really interesting element, very inert and expensive. So let's just move right along here. Palladium in the periodic table. Here's a beautiful, by the way periodic table that was produced by Theodore Gray, who's also made these wonderful posters and books. I highly recommend Theodore Gray's book, "The Elements". Rush right out and buy one. You can get one at Amazon I'm sure. And palladium is found sort of centrally in the table there. Here you can see a picture of palladium. It has a silvery white kind of look to it. Actually, it has almost a little bit of a brassy look. It's not quite silvery, silvery. It has a little brassy look to it as well. You can see there that palladium is element number 46 in the periodic table. So this is the 46th, Everything Matters that we've done. 46 is significant. It tells you how many protons are in the nucleus of palladium. Any time you have a nucleus that has 46 protons in it, it's palladium. There can be different numbers of neutrons and we'll get to those when we talk about isotopes. But 46 means there's 46 protons, there's 46 electrons and that sets the chemistry for palladium. It doesn't make any difference how many neutrons are in the nucleus. It's all about, chemistry is all in the electrons, it has nothing to do with the nucleus anyway. So palladium was discovered in about 1803 by this fellow, William Hyde Jackson Wollaston. And he discovered it from some crude platinum ore from South America. He didn't actually announce that he had a discover this until 1805. And by that time, other people were trying to take credit for things, but he does get the credit for the discovery. He named the element... Here's a picture of a palladium sponge. And he named the element palladium. And he did that because two months prior to his discovery, the asteroid Pallas had been discovered. And so he named his new element palladium after the asteroid Pallas. And here we can see a more modern picture of the asteroid Pallas. Just interestingly, it was only the second asteroid to have been discovered. The first one was Ceres. Get to that in just a moment. Pallas is one of the largest asteroids in the solar system, and it's kind of a probably a remnant protoplanet. It actually has about 7% of the mass of the entire asteroid belt. So it's the third, most massive asteroid about 3/4 the mass of Vesta, which was the fourth discovered asteroid. And 1/4 of the mass of Ceres, the first asteroid discovered and Ceres by the way, also gave its name to an element cerium, which we will be getting to fairly soon, I guess, within the next year or so. The sources of palladium in the world are quite widespread or deposits of palladium. And it usually palladium usually occurs in other platinum group metals, which are sort of in the middle of the table there, we'll get to that and are very rare. It's hard. It doesn't occur all by itself. You have to refine it from with other elements in the ore. The most extensive deposits, they're found in South Africa. There's a few in the Stillwater Complex in Montana, in the Sudbury Basin and Thunder Bay District of Ontario, Canada, which was in a previous, Everything Matters, the big nickel mine up in Sudbury. And also in the Norilsk Complex in Russia. And that complex actually accounts for almost 40% of the world's production. So aside from digging it out of the ground and refining it, another source of palladium is a recycling. Mostly from scrapped catalytic converters, which gives you a clue that one of the applications we're gonna talk about is catalytic converters. Now it is a very rare element and it only occurs on few places in the earth. So here's a periodic tables and endangered elements lists. The elements in blue, dark, dark blue, are limited ability, future risk to supply. And you can see that palladium is one of those that is in there for a future risk of supply. So we have to be careful and recycling is really important as far as palladium goes. Now, where does palladium come from? Palladium comes from mainly dying, low mass stars and much more exotically, and from a merging neutron stars. Actually more palladium comes from merging neutron stars that gets blown out into space when the neutron stars merge. I don't know if you can see below there, gold below there. There's mostly from merging neutron stars, and that's actually fairly new science that's been done in the last couple of years. Palladium in the middle of a table there, is a member of a large group of elements that are called transition metals. And that takes up the entire middle of the periodic table with the alkali metals over on the left hand side and the halogens and the rare and the noble gases over on the right hand side of the table. Now, it's also a member as I mentioned earlier of this very exclusive group called the platinum group of metals, PGM. And that contains three of the metals that we've already talked about. Well, two of them anyway. Ruthenium, rhodium, and today's element palladium, and then below them, the other platinum group elements, osmium, iridium, and platinum. These all kind of share properties, mainly that they're very, unreactive. They're noble metals. If we look at the abundances in the universe, we see that in the universe, palladium is not very abundant. It's the 59th most abundant element in the universe. It's pretty rare. If we look at it a little closer, how abundant is it in the sun? It's a little more abundant in the sun. It's the 49th most abundant element in the sun. The sun is at least a second generation star. So it's made out of stuff that other stars have already used. So other stars that have exploded and spread their debris into space, make up the sun. So we find a little more palladium in the sun. Meteorites have even a little bit more of the 45th most abundant element in meteorites. Especially metallic meteorites, which have a lot of nickel and iron in them. In the Earth's crust, however, since most of the metal in the Earth's crust has sunk to the center of the earth. In the Earth's crust, it's the 72nd most abundant element in the Earth's crust, very, very low abundance. And if you think that's low, in the oceans, there ain't none. And also in you and in me, there is no palladium. Now let's take a look at the atom itself. Let's look at the sizes here. If compared to a hydrogen atom, palladium is a fairly large element. It is about three times the size of a hydrogen. And that's true for most of the elements in the transition middle of the table there. It's about 169 picometers. A picometer is a millionth of a billionth of a meter. It's very small. I'm sorry, it's a thousandth of a millionth of a meter. So it's very, very small. We put that size sort of here on the table. You'll see that the size of the atom is actually right there in the middle. So it's medium-sized atom. And let's go and talk about that atom again. We were talking about isotopes. Well, isotopes here, all the isotopes of a palladium, there are 34 isotopes of palladium. And that number you see there, 91, 92, 93, all the way to one 124. Those numbers are the weight of the nucleus. That is the number of protons plus the number of neutrons. So if you subtract 46 from all those numbers, you get the number of neutrons in the nucleus. And all of these are still palladium. If you have them all mixed up, you would have, and did chemistry on them, they would all act exactly the same. You would have a very difficult time separating them chemically because the only difference here is in the nucleus, and remember all chemistry happens in the electron shells. Now of these, there are six stable isotopes of palladium, 102, 104, 105, 106, 108 & 110. And those make up various percentages of palladium that we find on the earth. Here we can see the percentages of natural palladium, everything from 1% for palladium 102 to the highest palladium 106 of 27%. So together, this makes up 100% of the palladium. Now, all of the other 42. How many did I say? 42 or 46 isotopes of palladium are radioactive and different isotopes have different half-lives. The shorter the half-life, the more radioactive it is. So, you know, any given lump, if it has a short half-life is gonna be giving off a lot more particles. And if we look at those a half-lives, here are the longest half-lives of about five isotopes. These are the five longest lived isotopes. These have a half-life of over one hour, and you can see that it varies greatly, in this case from 13 hours to 6 1/2 or for 8 hours rather to 6 1/2 million years. And that's 6 1/2 million years sounds like a long half-life, but it actually is compared to the age of the universe. It's not very long, which is why we know when we see palladium 107, that it was made somewhere either in the middle of a star or by a nuclear reaction or an atomic bomb or something like that. But again, these are the longest half-lives. All the others are less than an hour. So if we look at some of the other qualities of palladium. It has a fairly high density. It's a density of 12, a little over 12 grams per cubic centimeter. Everybody remembers what the density of water is of course, right? Density of water is 1 gram per cubic centimeter. And I've placed a few other densities down here, so you can compare. So gasoline is a 0.7 grams per cubic centimeters, so gasoline floats on water. And sodium, which is slightly less than water also floats on water. It's very surprising to see metal floating on water. All the way down to a tungsten and iron, we can see actually lead is about 11 1/3 grams. Lead is actually less dense than palladium. So if you had a brick of a palladium and a brick of lead, the brick of palladium that were both the same size, the brick of palladium would be heavier than the brick of lead. Let's compare those on one of those charts. So we have the most dense on the left and the least dense on the right. And here we can see... And I put, usually when we do this in person, we have a set of blocks that you can lift up and feel the density of these things. And you can see there that I have blocks there for tungsten and I'm labeling them lead and copper. You can see the density is appearing and iron and titanium and aluminum and magnesium. And finally there is the density for palladium, which is fairly high. Higher than lead. Sorry, my blocks there have also two blocks that are not elements, maple and plastic. But next time we're able to do this at the Exploratorium. Come on in and we'll... You can feel these blocks for real on your own. Now, palladium has a fairly high melting point. Its melting point is about a 1,555 degrees centigrade. Oh sorry, I'm not supposed to say centigrade, Celsius. And it's about the 23rd highest melting point of the elements. It also has the 34th highest boiling point at almost 3000 degrees Celsius, C. Another quality that's interesting is it has a fairly low, that's the melting point. Has a fairly low thermal expansion. So here's the elements, thermal expansion. The highest thermal expansion rate at the left, which is mercury followed by gallium and sodium. And the least at the right side of the chart, silicon and molybdenum and tungsten, and a few of those, and our element for today, Palladium is sort of in the middle there. It expands by about one part in 100,000 for every degree, C, that you change. As you raise the temperature, every degree, C, it increases in size by about one part in 100,000. As far as hardness goes, it's kind of a middle of the road hardness. If we look at the most scale of hardness. Let's circle it here, there's palladium. And you can see palladium has a Mohs scale of hardness of about five, the same as tooth enamel. So don't go biting down on any palladium today. It's not quite as hard as things like quartz and silicon but it's harder than iron and nickel and platinum. So it's sort of in the mid there. If we chart that out again with the hardest elements on the left and the least hard element on the right, it's about in the middle there. So we see the hardest element, chromium, and then boron on the left. And we see the softest elements, caesium and potassium, rubidium, and sodium those metals, the alkaline metals over on the right hand side of the chart. If you look at the periodic table of spectra here, the spectrum of palladium has a few bright lines and mostly in the greens and cyan part of the spectrum. There's very few colors it gives off, if we put it into a flame. Very few reds and very few blues and violets. So if you could burn palladium, which you probably don't wanna do, we'll find out why in the next slide, it would give off kind of a greenish flame. So let's see why you would not want to burn palladium. And that has to do with its price. Palladium, which has been varying widely has been recently on the average of about $2,500 per ounce. Not quite twice that of gold, but pretty close. So it's a very, very rare and very expensive element. Let me bring my camera back here. 'Cause I actually have a sample that I can show you. So let me bring my camera back here. And I have a sample of palladium that I can show you here. It's a little piece of palladium wire. There it is at the bottom of the tube there. Sorry, it's not in focus. There we go. That's probably a little bit better. You can see that this is a piece of wire, it's usually used in chemical analysis where they don't want corrosive things happening, and also it's used because it's very good at catalyzing reactions. So let's get back to the slides here. We can see that the price of palladium has varied widely over the last year, especially recently due to the given uncertainties in the world today, but it had reached a very high price just recently of well over a $2,500 an ounce. So what are the applications of palladium? One obvious one is jewelry. And here you can see a wedding band, made out of polo palladium. And this one, this is a... It's not a large wedding band, but something about this size of palladium is gonna cost you at least $1,000, probably more. The nice thing about using it for jewelry, is like gold and platinum, it does not react with oxygen at normal room temperature, so it doesn't tarnish in the air. So it stays nice and shiny. It's been used in a jewelry since about 1939 as an alternative to platinum. And like platinum, you can mix it with gold and change the color of gold. You've heard of rose gold. Since we've been getting iPhones now that have rose gold color, but if you mix a palladium or platinum with gold, you get white gold. So that's another use of palladium is to in jewelry. Now its main use is not in jewelry. It's main use is in automotive, in the automotive industry as a catalytic converter. Here, you see a catalytic converter that's kind of been sliced open and the... I'm gonna use my cursor here and bring my cursor in. This has been sliced open and you can see this kind of honeycomb like stuff is where the exhaust gases flow through. And this material here has been plated with a very, very, very thin layer of palladium and platinum as well sometimes. Let's take a look at that a little bit closer. As a matter of fact, by the way about 50% of the world palladium production is dedicated as a catalyst in these three-way catalytic converters in cars. So if you took that core out and looked at it end on it would look something like this. This is the core from a catalytic converter. And when you pass the exhaust gases through this, the catalytic converter gets very hot and it converts as much as 90% of the harmful gases in automobile exhaust, and those harmful gases would be hydrocarbons and carbon monoxide and nitrogen dioxide into less noxious substances like nitrogen and carbon dioxide and water vapor. So it's a very important element for keeping our air clean. Another important use in electronics is to make these things called multi-layer ceramic capacitors or MLCCs. These things that you see here in the picture are very, very small. There are probably a millimeter or two millimeters long in size, and a capacitor... What is a capacitor? A capacitor doesn't allow current to flow it, but it's made up of a set of parallel plates that can charge so you can charge a capacitor up and then the capacitor can discharge. And that's one of the fundamental components of electronics. Capacitors and resistors, transistors, and inductors, all very important parts of your basic electronics. And these, let's take a look at where these might occur. You can see these if you have some open electronics at home. If you're like me and kind of a geek and you play with things like a Raspberry Pi. Here's a Raspberry Pi kind of close up. You can see there's a lot of these multi-layer ceramic capacitors on the board here. I'm gonna circle them right there. There's a bunch of them right there. There's also a few on the lower left hand side of the board as well. But these are all soldered onto the board directly and provide the services that they normally provide. But if we zoomed in on one of those things, it would look something like this. Again, you can see each end-cap of that multi-layer ceramic capacitor, is hooked up to a series of interleaved plates and those plates get charged and then discharged. And that makes up the capacitor. So because of its high melting point and noncorrosive properties, it's also useful in electrical contacts. For instance, in reed switches, and this is the third time I've gotten to use this slide because we also used it in ruthenium and rhodium. And we'll probably use it again when we get to platinum. But the contacts of a reed switch are plated, sometimes with palladium. If we took a closeup view here. Here's a closeup view of a reed switch. You can see that these two contacts come in this in a glass envelope. And these two contacts meet in the center of the glass envelope and those two little larger lumps at the end of the arms there, are usually made out of some kind of a magnetic material like iron. And that iron is plated with palladium. And because they're plated with palladium, they don't, it's harder for those things to be eroded away by electrical sparks when they occur. Let's actually look at that in action. So here is a reed switch and in action, and you can sort of barely see it clicking together and clicking apart. You might have to do this full resolution on your screen. But if you bring a magnet nearby, you can't see the magnet being brought nearby here. It magnetizes the two lumps of iron at the ends of those arms and they causes them to stick together. Otherwise they're kind of sprung apart. And so here you see the action actually happens. This is a reed switch that detects a magnet going by, often used in alarm switches, for doors. You put a magnet on your door and the alarm switch goes on the frame of your door. And when the door is closed, it makes contact. When you open the door, the magnetic field goes away and opens the contact. Also has been used in automotive parts and things like that. Speaking of automotive parts, it's also, palladium is also used in spark plugs. Usually I have to admit here, aircraft spark plugs, not in your car. And because of a time melting point and noncorrosive nature, it's plated, and I'm gonna show you here right onto the ends. Oops! Sorry, let me go back up, back one slide. I messed that up. It's plated onto the tips here where the spark jumps between this and that little tip right there. And so to keep it from corroding, you can plate it with platinum or palladium or rhodium or any of those kind of platinum level, platinum elements. So I kind of gave away the next slide. The next slide we're gonna talk a little bit about, is palladium used in numismatics and philately or stamp collecting. Coin and stamp collecting, this Tonga paper coin has been vacuum deposited on with some palladium. So it's again, not super valuable, but it's kind of cool. And that a German stamp on the right hand side, is actually celebrating the element palladium. I think we should do a series of stamps that celebrate the elements. I think that would be a really nice. As far as real coins go, back when this right near the end of the Soviet Union in 1989, they struck a commemorative coin, a 25 ruble coin that was made of palladium. So it was probably a fairly small coin. I'll bet, this has really magnified. Of the more practical and health related applications, glucose test strips often have a palladium layer inside of them. These are if your test your blood glucose, if you have diabetes and then you will use these strips and these trips do have palladium in them. So you have palladium! If you have blood test strips, glucose test strips. If you work with an electron microscope. An electron microscope shoots a beam of electrons at a very small sample. And that small sample has to be coated with something that is conductive. And normally you would put your sample right here on this little post and you would shoot and you shoot electrons, up at this target up here. And that it can be various metals like platinum or iridium or other metals. And it knocks the atoms off of there and the atoms kind of rain down on top of your sample right here and coat them. And that can make your sample, it should it make your sample electrically conductive because it has to be useful in an electron microscope. So when you put your sample there and take it out, they're usually quite nice. Here for instance, is a gold coated spider. And here's a gold coated ant. But palladium is also one of those elements that they use to coat things, to make them electrically conductive. One of the important uses in industry is in fuel cells. A fuel cell you put a hydrogen gas in one inlet right here, and you put oxygen gas in this inlet right here, and the hydrogen and the oxygen diffuse through carbon particles that have been impregnated with platinum or palladium and into the electrolyte here. But they make electrons and positive charges, which you can hook your car up to the positive and negative right here or your spacecraft. And so here, what they've done is it exhausts only water vapor. So you're taking hydrogen in an oxygen and producing water vapor out and electricity. So this is a hydrogen oxygen fuel cell, and it uses palladium or platinum as a part of the catalyst to produce the reaction and remove electricity. One of the more notorious palladium experiments involve these two guys, Martin Fleischmann and Stanley Pons. They had a little cell. Then that cell had a palladium electrode in the middle of it. The thing that you see there in the diagram labeled cathode, in a flask of heavy water. So heavy water is made up of heavy high water, H2O, made of heavy hydrogen called deuterium, an electrolyte, something to allow electricity conduct. And they noticed that they thought they were getting more energy out than they were putting in. Everybody tried to duplicate this experiment. Nobody succeeded. So cold fusion was just, unfortunately, a dream that never happened. It would have been really nice if that had actually worked. Palladium absorbs hydrogen, and it does it quite, quite well. You could actually use it to store hydrogen in cars, but given the cost of palladium and the amount of palladium you'd need, it's just not practical to use it to absorb hydrogen in your car, as a fuel tank. In your mouth, you might find palladium. Palladium is used in small amounts, about 1/2% in some alloys of dental amalgam. That metal if they press into your teeth. And they use it to decrease corrosion and increase the metallic luster of the restoration. So you might have some palladium in your mouth, but that's probably the only place you have it in your body because palladium serves absolutely no purpose in human biology. There is no natural biological role and it is not found in your body. And that kind of brings us to the end here with our elemental haiku by Mary Soon Lee. She's made up haiku's for all of the elements. So her haiku for palladium was, "How much hydrogen must you swallow up to please cold fusion dreamers?" And that takes, that is this issue of Everything Matters, Tales from the Periodic Table. The next one we'll be doing is the next element up in the table, element 47, which is silver. And well, that won't happen on May 21st. It'll happen whenever it happens. Sorry, that I forgot to edit that slide, but whenever we get to it it'll happen. Maybe it will happen even sooner than May 21st. Maybe on May 21st, but definitely in May sometime or before. With all that, we'd like to thank you all for listening to Everything Matters, Tales from the Periodic Table. I am your host, Ron Hipschman. And we hope that you will come back and visit us for future editions of Everything Matters. Thank you very much.