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For us, life unfolds on human scales.
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Miles...feet...inches.
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But beneath the surface of things is another
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realm a billion times smaller than we are. A dimension that holds the secrets to understanding our world.
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What makes steel strong...
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...why ice cream is delicious...
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...what makes life possible.
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Secrets that help us create what we imagine.
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"The human creativity of chemistry. There's just nothing more beautiful than them."
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This is the realm of chemistry and these are it's greatest discoveries.
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Ancient Greek philosophers believed there were just four elements; earth, air, fire and water.
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And that air was the underlying element.
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A single substance responsible for the make up of everything in the world.
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Centuries later Leonardo Da Vinci was among the first to suggest that instead of being
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an element, air might consist of two different gases. It remained a mystery until our first great discovery.
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England, the latter part of the eighteenth century, clergymen and sometimes
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scientist Joseph Priestley conducted a series of experiments searching for new 'airs' what today we call gases.
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To find out more about what Priestley was up to, I paid a visit to
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Arnold Thackray. President and historian at the Chemical Heritage Foundation in Philladelphia Pennsylvania.
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"Priestley wrote and wrote and wrote on every subject that you've ever thought of.
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He wrote about history, he wrote about religion, he wrote about politics, he wrote..
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"Science?" He wrote about science endlessly and Priestley was the man who knew everything.
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He would tell you the practice of it, the history of it, the theory of it and he was quite literally
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the man who knew everything."
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But along with everything else Priestley did this famous experiment right?
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"That's exactly correct, and there are two things that go into that experiment.
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The one is Mercury. This strange substance that's simultaneously a liquid and metal.
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And that's just crazy. Who ever heard of a liquid metal and so it was really puzzling.
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What is this thing? People were fascinated by it and so they wanted to explore it. Of
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course the other thing that went into it was the technology to deal with gases and here
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in Priestley's experiments and observations on different kinds of air we have the technology
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of collecting gases over liquids. "In tubes that you can see through." Exactly, so you
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can see the gas, you can see what's happening to the gas and now you really are in business.
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What Priestley does is he takes a burning glass to give it heat, a lens. He focuses it on
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this orange powder, the mercuric calx, he heats it, it changes into this metal mercury
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and a gas comes off. But Priestley doesn't really realize what it is that he's found."
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The answer would emerge in 1774 after Priestley paid a visit to Paris and shared
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the story of his discovery with another scientist... Antoine Lavoisier. "Paris is a marvelous place
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for Priestley to visit because Antoine Lavoisier is in Paris, talk of the town, doing the work
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that will end up as his elementary text on chemistry. And Lavoisier who is also mucking
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about with gases, hears what Priestley has done, is fascinated by the report of this
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new air, decides he'll repeat the experiment. He has lots of apparatus, better apparatus.
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He's a meticulous experimenter. And among other things he weighs things. Lavoisier, by
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weighing says something is being emitted. He calls the thing emitted oxygen. He rewrites
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a whole script of chemistry and he creates a list of elements that we still use today;
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Oxygen, Hydrogen, Sulfur. You can correctly say Priestley discovered Oxygen but Lavoisier
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invented it. So with Priestley's experimental work on gases, with discovery of Oxygen,
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with Lavoisier's articulation of a system of language, we have the whole conceptual
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scheme in which Nineteenth Century academic work is built. Twentieth Century industrial
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innovation. We have pharmaceuticals, we have biotechnology, we have cell phones. "Plastics?"
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We have plastics. That's exactly right. And all these things begin with the discovery
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of Oxygen. That's where it starts. "That's a lot to breathe in".
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In the early Nineteenth Century a British school teacher named John Dalton was hard at work pursuing his fascination
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with chemistry which would lead to our next great discovery. Dalton's experiments showed
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that the known elements such as Oxygen, Hydrogen, and Carbon combined in definite and constant
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proportions. From his calculations he hypothesized that the elements must be made up of smaller
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invisible pieces of matter with relative and distinctive weights. He called these pieces
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of matter atoms. "So, what did Dalton discover?" Dalton's great discovery was what he called
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the 'relative weights of ultimate particles'. "Ultimate particles." That's what he called
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it. It's a lovely phrase. Later on when he went public it becomes atomic weights. We
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know it as atomic weights. but it was ultimate particles. "So he used the word atoms?" He used the word atoms, the idea
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of an atom of course goes back to Democritus, the problem is, it's an idea. Is it any use?
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And Dalton was the man who made the idea useful. That was his great contribution. "From his
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work, Dalton developed what came to be known as his Atomic Theory. A revolutionary new
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system that defined the relationship between atoms and the elements. And it's an enormously
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simple system and Dalton thinks very simply, very visually. Here are the elements, here
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are the weight of the elements. Here are the complex molecules, and it's a wonderfully
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effective system. It connects the thing that chemists can do, weigh things in balances
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with the things that you can't see; the ultimate world of atoms and that's genius. How important
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was Dalton's discovery? His Atomic Theory helped generations of scientists further unravel
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the mysteries of the atomic and molecular world, including our next great discovery.
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In the early 1800's French Chemist Joseph Gay-Lussac was conducting a series of experiments
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designed to study Dalton's Atomic Theory when he observed something odd. When he combined
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equal volumes of different gases, and measured their reactions, the gases often produced
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twice the volume than he expected. How was this possible? The answer was provided in
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1811 by Amedeo Avogadro; a physics professor at the University of Turin in Italy.
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While studying the results of Gay-Lussac's research, Avogadro had an insight. At the
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time, it was believed that gases were made of single atoms. Avogadro realized this
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assumption was wrong. The gases were made of multiple atoms. What came to be known as
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molecules. The realization that atoms could be rearranged to form molecules was the breakthrough
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that enabled scientists to move out of the chemistry dark ages and begin systematically
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creating new compounds.
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Our next great discovery occurred in the Nineteenth Century
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when many chemists believed that organic substances from organisms or living things were somehow
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different from inorganic substances from non-living things, but that was about to change.
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In 1828 Friedrick Wohler was working in his lab when something caught his eye.
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Wohler had placed two inorganic chemicals in a beaker; Potassium Cyanate and Ammonium Sulfate.
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Now when he looked at the beaker it contained a grams worth of small white needle shaped
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crystals. What made this remarkable was that Wolher thought he had seen these exact same
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crystals once before, but with an important difference. Those crystals had been organic.
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He had crystalized them while studying the chemistry of various substances found in urine.
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To make sure he wasn't mistaken, Wolher analyzed the new crystals. There was no mistake.
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These crystals were the same as those he had isolated before. He had made urea, which was something
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that had come out of a living thing. He had made it out of inorganic substances. Later
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he said in a personal letter not in the paper that he wrote about it that I have made
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urea without a kidney. He knew what he had done. "Meet Roald Hoffmann, winner of the
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1981 Nobel Prize in chemistry for developing a theory to explain organic chemical reactions.
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So why is this discovery of artificially making urea? Why is that a great discovery?
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You know there comes a time when you need a discovery and it's sometimes a single one to cross a
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border, to break down a wall. This is what this discovery was. It's not that it was so
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important in and of itself but at the time that it came, the simple making of urea out
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of two inorganic chemicals. When it came, it caught people's attention. The whole story
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of the discovery is about the underlying basis, the building blocks of all matter, organic
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and inorganic being the same; atoms.
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If these lego bricks had existed in the early part
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of the Nineteenth Century, chemists could have used them to help illustrate something they
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were seeing in their experiments. A phenomenon that led to our next great discovery.
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The atoms of particular elements such as Sodium and Chlorine seemed to combine with each other
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according to fixed ratios. It was this combining power of atoms that inspired German chemist
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August Kekule to develop a system for visualizing the chemical structure of various molecules.
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Kekule represented the atoms by their symbols, then added marks to indicate how they bonded
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with each other. Like links in a chain. It was a simple yet elegant formula. Chemists
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now had a device for clearly illustrating the chemical structures of the molecules they
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were studying. There was just one problem. Benzene was the only known chemical that would
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not fit Kekule's formula. Benzene's chain of Carbon and Hydrogen atoms required more
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combining power than the formula would allow.
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"And all these organic chemistry professors are puzzling about it and offering different explanations.
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And one of them; August Kekule sitting by the fire one evening falls asleep and starts to dream about a snake.
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And if you think about a snake, what Kekule dreams of is the snake catches it's own tail.
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And if you think about this, maybe the thing is a ring and that gives you an answer to the puzzle.
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"The six Carbon atoms of the Benzene molecule weren't linked in a chain.
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Like the snake, they formed a ring. Each with a Hydrogen atom attached, with alternating
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single and double bonds. Within a short time Kekule's insight was confirmed and its effect
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was revolutionary. Chemists knew that all organic substances contained one or more carbon
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atoms and their molecules. With Kelkule's discovery they now had the underlying formula
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to explain how carbon combined with other molecules
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to form a world of chemical compounds. The modern era of organic chemistry was born.
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Now with this thing being so simple, that is to say the snake bites its tail.
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Why is this considered a great discovery? --Here's a recipe for new drugs, new medicines,
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new understanding. If you go back in time in Dalton's day couple of hundred compounds.
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Soon it's a couple of thousand, soon it's 10,000. Astonishing. Soon it's a hundred thousand.
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Last year 15 million new compounds were registered, all built on this simple template.
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This is a work of genius.
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In 1869, a Russian chemistry professor named Dmitri Mendeleev was writing
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a text book for his students, when he began to wonder how we could best explain to them
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the 63 elements that were known at the time. To help formulate his thoughts
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he constructed a card for each element. On each card he wrote the name of the element,
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its atomic weight, it's typical properties, and its similarities to other elements.
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He then laid the cards out like a game of solitaire and began arranging them over and over, searching for patterns.
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Then came the moment of discovery.
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Before him was something extraordinary. The elements fell into 7 vertical groupings.
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Each periodic grouping had members that resembled one another,
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both chemically and physically. Mendeleev had discovered the periodic table of the elements,
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a map showing how all of the elements related to one another.
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A map so precise that Mendeleev believed he could also use it to predict the
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existence and properties of three elements no one had yet discovered.
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One would be like Boron he said. One like Aluminum, and one like Silicon.
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Eventually the elements were discovered and Mendeleev was proven right.
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There was actually a little bit of controversy because a German chemist and Lothar Meyer
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had come up with roughly the same idea but Meyer didn't quite have as much courage. So
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that's actually an interesting thing.
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Here's this German who comes up with the same idea of periodicity
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of which there were hints already before, but he doesn't make the predictions
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that Mendeleev does. So here we see the power of a risky prediction in
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having people except a theory. There is nothing more powerful
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than making a prediction that's not obvious. --And then have it come true."
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And have it come true. The periodic table is our icon. I mean that
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it's what we associate with chemistry. You go into any chemistry room and you see it.
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Why is the periodic table of elements significant? it forever changed the way that everyone would
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learn and understand the elements.
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The periodic table of elements is to chemistry as notes of music are to a Beethoven sonata.
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In honor of Mendeleev, his name is now literally
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attached to the periodic table. The element 101 was named after him. It's called Mendelevium.
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It's not only chemists who like the periodic table, I hear you carry one around.
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--I do carry one, yes sir. --Show me!
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--You never know. And I seem to use it a lot." --Let's see.
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--It's a small one. --So I'm going to give you a test. Um what is under Nitrogen on the periodic table?
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--Nitrogen is 7. --Yes.
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--Well I have to think a second. "Sulfur."
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--No you're wrong. Close, you're one off. --That's why I carry it.
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--It's Phosphorus. --Oh Phosphorous, Phosphorus. 15.
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--Phosphorus is 15? -- Yeah, you have to add 8 at that point.
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See that's why I carry it. I can't remember. So it's
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seven plus 8. 15, Phosphorus. Okay. There's there's a pattern there. I get it now.
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At the turn of the 19th century, electricity was all the rage.
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people were busy making batteries and connecting them to just about
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anything to see the reaction. Electricity was like a new kind of fire.
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One of the great battery junkies of the day was Humphry Davy, the self taught English chemist.
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In 1807 Davey was performing a battery experiment in his lab.
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He melted some potash; a mineral found in the ground,
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that also forms in the ashes of wood. Chemists had speculated that potash was a compound
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of several elements, but had not been able to prove it. Davy wanted
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to see if electricity might provide the answer.
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He ran some wires from one of his biggest batteries to the melted potash.
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Pure Potassium began to emerge. Davy had discovered the power of electricity to react with chemicals and transform them.
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Eventually electrochemistry led to the rise of the
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aluminum industry, the production of semiconductors, solar panels, LED displays, even rechargeable lithium batteries.
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In the 1850s Robert Bunsen and his research collaborator Gustav Kirchhoff
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conducted a series of experiments to determine why substances
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emitted specific colors when placed in a flame. The color they determined, indicates what
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elements are present in the substance. For example, if Sodium is
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placed in a flame, they observe shades of yellow.
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Copper, shades of green. Strontium, shades of red.
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That was a good one.
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While watching the experiments Kirchoff was reminded of how a prism spreads light into a rainbow of colors.
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So, using a prism and the pieces of a small telescope Bunsen and Kirchoff built the first spectroscope,
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an analytical device they hoped would help them see the spectra
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coming from heated substances. And it worked. As an element
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was put into the flame of a bunsen burner, the light from the heated substance passed
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through the prism of the spectroscope where it then spread into a
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ribbon-like spectrum of colors, riddled with dark lines. The combinations
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of bright colors and dark lines were like barcodes, indicating what atoms were present.
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When burned, each element produced a completely unique spectrum.
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Using their spectroscope, Bunsen and Kirchoff were able to discover two new elements; Cesium and Rubidium.
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One day Bunsen and Kirchoff decided to test their invention with sunlight.
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It produced a spectrum that featured two lines that were identical to those in the spectrum
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produced by sodium. Bunsen and Kirchoff had discovered the presence
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of sodium in the sun 93 million miles away.
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Suddenly scientists had a tool to help them study the chemistry of the heavens.
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[Lift off. We have lift off.]
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Today the legacy of this great discovery lives on in the exploration of space.
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A form of spectroscopy is being used to study the
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atmospheres of planets, to search for signs of water. Signs of life.
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Our next great discovery is the story of Joseph Thomson and the electron.
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["Here we are."] --So everything that we can see is made of chemicals.
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--That's right --What's the future?"
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--And they're all bonded through electron interactions. --Thank goodness.
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"To find out about it I paid a visit to Harvard University.
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Dudley Herschbach is a professor here and winner of the 1986 Nobel Prize in Chemistry...
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for his research into the dynamics of chemical elementary processes.
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--So Thomson discovered the electron. --Well it is of course said that way, but he didn't discover it in
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the sense that he said, "Eureka! I've got this thing. Here it is." He did an experiment