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  • For us, life unfolds on human scales.

  • Miles...feet...inches.

  • But beneath the surface of things is another

  • realm a billion times smaller than we are. A dimension that holds the secrets to understanding our world.

  • What makes steel strong...

  • ...why ice cream is delicious...

  • ...what makes life possible.

  • Secrets that help us create what we imagine.

  • "The human creativity of chemistry. There's just nothing more beautiful than them."

  • This is the realm of chemistry and these are it's greatest discoveries.

  • Ancient Greek philosophers believed there were just four elements; earth, air, fire and water.

  • And that air was the underlying element.

  • A single substance responsible for the make up of everything in the world.

  • Centuries later Leonardo Da Vinci was among the first to suggest that instead of being

  • an element, air might consist of two different gases. It remained a mystery until our first great discovery.

  • England, the latter part of the eighteenth century, clergymen and sometimes

  • scientist Joseph Priestley conducted a series of experiments searching for new 'airs' what today we call gases.

  • To find out more about what Priestley was up to, I paid a visit to

  • Arnold Thackray. President and historian at the Chemical Heritage Foundation in Philladelphia Pennsylvania.

  • "Priestley wrote and wrote and wrote on every subject that you've ever thought of.

  • He wrote about history, he wrote about religion, he wrote about politics, he wrote..

  • "Science?" He wrote about science endlessly and Priestley was the man who knew everything.

  • He would tell you the practice of it, the history of it, the theory of it and he was quite literally

  • the man who knew everything."

  • But along with everything else Priestley did this famous experiment right?

  • "That's exactly correct, and there are two things that go into that experiment.

  • The one is Mercury. This strange substance that's simultaneously a liquid and metal.

  • And that's just crazy. Who ever heard of a liquid metal and so it was really puzzling.

  • What is this thing? People were fascinated by it and so they wanted to explore it. Of

  • course the other thing that went into it was the technology to deal with gases and here

  • in Priestley's experiments and observations on different kinds of air we have the technology

  • of collecting gases over liquids. "In tubes that you can see through." Exactly, so you

  • can see the gas, you can see what's happening to the gas and now you really are in business.

  • What Priestley does is he takes a burning glass to give it heat, a lens. He focuses it on

  • this orange powder, the mercuric calx, he heats it, it changes into this metal mercury

  • and a gas comes off. But Priestley doesn't really realize what it is that he's found."

  • The answer would emerge in 1774 after Priestley paid a visit to Paris and shared

  • the story of his discovery with another scientist... Antoine Lavoisier. "Paris is a marvelous place

  • for Priestley to visit because Antoine Lavoisier is in Paris, talk of the town, doing the work

  • that will end up as his elementary text on chemistry. And Lavoisier who is also mucking

  • about with gases, hears what Priestley has done, is fascinated by the report of this

  • new air, decides he'll repeat the experiment. He has lots of apparatus, better apparatus.

  • He's a meticulous experimenter. And among other things he weighs things. Lavoisier, by

  • weighing says something is being emitted. He calls the thing emitted oxygen. He rewrites

  • a whole script of chemistry and he creates a list of elements that we still use today;

  • Oxygen, Hydrogen, Sulfur. You can correctly say Priestley discovered Oxygen but Lavoisier

  • invented it. So with Priestley's experimental work on gases, with discovery of Oxygen,

  • with Lavoisier's articulation of a system of language, we have the whole conceptual

  • scheme in which Nineteenth Century academic work is built. Twentieth Century industrial

  • innovation. We have pharmaceuticals, we have biotechnology, we have cell phones. "Plastics?"

  • We have plastics. That's exactly right. And all these things begin with the discovery

  • of Oxygen. That's where it starts. "That's a lot to breathe in".

  • In the early Nineteenth Century a British school teacher named John Dalton was hard at work pursuing his fascination

  • with chemistry which would lead to our next great discovery. Dalton's experiments showed

  • that the known elements such as Oxygen, Hydrogen, and Carbon combined in definite and constant

  • proportions. From his calculations he hypothesized that the elements must be made up of smaller

  • invisible pieces of matter with relative and distinctive weights. He called these pieces

  • of matter atoms. "So, what did Dalton discover?" Dalton's great discovery was what he called

  • the 'relative weights of ultimate particles'. "Ultimate particles." That's what he called

  • it. It's a lovely phrase. Later on when he went public it becomes atomic weights. We

  • know it as atomic weights. but it was ultimate particles. "So he used the word atoms?" He used the word atoms, the idea

  • of an atom of course goes back to Democritus, the problem is, it's an idea. Is it any use?

  • And Dalton was the man who made the idea useful. That was his great contribution. "From his

  • work, Dalton developed what came to be known as his Atomic Theory. A revolutionary new

  • system that defined the relationship between atoms and the elements. And it's an enormously

  • simple system and Dalton thinks very simply, very visually. Here are the elements, here

  • are the weight of the elements. Here are the complex molecules, and it's a wonderfully

  • effective system. It connects the thing that chemists can do, weigh things in balances

  • with the things that you can't see; the ultimate world of atoms and that's genius. How important

  • was Dalton's discovery? His Atomic Theory helped generations of scientists further unravel

  • the mysteries of the atomic and molecular world, including our next great discovery.

  • In the early 1800's French Chemist Joseph Gay-Lussac was conducting a series of experiments

  • designed to study Dalton's Atomic Theory when he observed something odd. When he combined

  • equal volumes of different gases, and measured their reactions, the gases often produced

  • twice the volume than he expected. How was this possible? The answer was provided in

  • 1811 by Amedeo Avogadro; a physics professor at the University of Turin in Italy.

  • While studying the results of Gay-Lussac's research, Avogadro had an insight. At the

  • time, it was believed that gases were made of single atoms. Avogadro realized this

  • assumption was wrong. The gases were made of multiple atoms. What came to be known as

  • molecules. The realization that atoms could be rearranged to form molecules was the breakthrough

  • that enabled scientists to move out of the chemistry dark ages and begin systematically

  • creating new compounds.

  • Our next great discovery occurred in the Nineteenth Century

  • when many chemists believed that organic substances from organisms or living things were somehow

  • different from inorganic substances from non-living things, but that was about to change.

  • In 1828 Friedrick Wohler was working in his lab when something caught his eye.

  • Wohler had placed two inorganic chemicals in a beaker; Potassium Cyanate and Ammonium Sulfate.

  • Now when he looked at the beaker it contained a grams worth of small white needle shaped

  • crystals. What made this remarkable was that Wolher thought he had seen these exact same

  • crystals once before, but with an important difference. Those crystals had been organic.

  • He had crystalized them while studying the chemistry of various substances found in urine.

  • To make sure he wasn't mistaken, Wolher analyzed the new crystals. There was no mistake.

  • These crystals were the same as those he had isolated before. He had made urea, which was something

  • that had come out of a living thing. He had made it out of inorganic substances. Later

  • he said in a personal letter not in the paper that he wrote about it that I have made

  • urea without a kidney. He knew what he had done. "Meet Roald Hoffmann, winner of the

  • 1981 Nobel Prize in chemistry for developing a theory to explain organic chemical reactions.

  • So why is this discovery of artificially making urea? Why is that a great discovery?

  • You know there comes a time when you need a discovery and it's sometimes a single one to cross a

  • border, to break down a wall. This is what this discovery was. It's not that it was so

  • important in and of itself but at the time that it came, the simple making of urea out

  • of two inorganic chemicals. When it came, it caught people's attention. The whole story

  • of the discovery is about the underlying basis, the building blocks of all matter, organic

  • and inorganic being the same; atoms.

  • If these lego bricks had existed in the early part

  • of the Nineteenth Century, chemists could have used them to help illustrate something they

  • were seeing in their experiments. A phenomenon that led to our next great discovery.

  • The atoms of particular elements such as Sodium and Chlorine seemed to combine with each other

  • according to fixed ratios. It was this combining power of atoms that inspired German chemist

  • August Kekule to develop a system for visualizing the chemical structure of various molecules.

  • Kekule represented the atoms by their symbols, then added marks to indicate how they bonded

  • with each other. Like links in a chain. It was a simple yet elegant formula. Chemists

  • now had a device for clearly illustrating the chemical structures of the molecules they

  • were studying. There was just one problem. Benzene was the only known chemical that would

  • not fit Kekule's formula. Benzene's chain of Carbon and Hydrogen atoms required more

  • combining power than the formula would allow.

  • "And all these organic chemistry professors are puzzling about it and offering different explanations.

  • And one of them; August Kekule sitting by the fire one evening falls asleep and starts to dream about a snake.

  • And if you think about a snake, what Kekule dreams of is the snake catches it's own tail.

  • And if you think about this, maybe the thing is a ring and that gives you an answer to the puzzle.

  • "The six Carbon atoms of the Benzene molecule weren't linked in a chain.

  • Like the snake, they formed a ring. Each with a Hydrogen atom attached, with alternating

  • single and double bonds. Within a short time Kekule's insight was confirmed and its effect

  • was revolutionary. Chemists knew that all organic substances contained one or more carbon

  • atoms and their molecules. With Kelkule's discovery they now had the underlying formula

  • to explain how carbon combined with other molecules

  • to form a world of chemical compounds. The modern era of organic chemistry was born.

  • Now with this thing being so simple, that is to say the snake bites its tail.

  • Why is this considered a great discovery? --Here's a recipe for new drugs, new medicines,

  • new understanding. If you go back in time in Dalton's day couple of hundred compounds.

  • Soon it's a couple of thousand, soon it's 10,000. Astonishing. Soon it's a hundred thousand.

  • Last year 15 million new compounds were registered, all built on this simple template.

  • This is a work of genius.

  • In 1869, a Russian chemistry professor named Dmitri Mendeleev was writing

  • a text book for his students, when he began to wonder how we could best explain to them

  • the 63 elements that were known at the time. To help formulate his thoughts

  • he constructed a card for each element. On each card he wrote the name of the element,

  • its atomic weight, it's typical properties, and its similarities to other elements.

  • He then laid the cards out like a game of solitaire and began arranging them over and over, searching for patterns.

  • Then came the moment of discovery.

  • Before him was something extraordinary. The elements fell into 7 vertical groupings.

  • Each periodic grouping had members that resembled one another,

  • both chemically and physically. Mendeleev had discovered the periodic table of the elements,

  • a map showing how all of the elements related to one another.

  • A map so precise that Mendeleev believed he could also use it to predict the

  • existence and properties of three elements no one had yet discovered.

  • One would be like Boron he said. One like Aluminum, and one like Silicon.

  • Eventually the elements were discovered and Mendeleev was proven right.

  • There was actually a little bit of controversy because a German chemist and Lothar Meyer

  • had come up with roughly the same idea but Meyer didn't quite have as much courage. So

  • that's actually an interesting thing.

  • Here's this German who comes up with the same idea of periodicity

  • of which there were hints already before, but he doesn't make the predictions

  • that Mendeleev does. So here we see the power of a risky prediction in

  • having people except a theory. There is nothing more powerful

  • than making a prediction that's not obvious. --And then have it come true."

  • And have it come true. The periodic table is our icon. I mean that

  • it's what we associate with chemistry. You go into any chemistry room and you see it.

  • Why is the periodic table of elements significant? it forever changed the way that everyone would

  • learn and understand the elements.

  • The periodic table of elements is to chemistry as notes of music are to a Beethoven sonata.

  • In honor of Mendeleev, his name is now literally

  • attached to the periodic table. The element 101 was named after him. It's called Mendelevium.

  • It's not only chemists who like the periodic table, I hear you carry one around.

  • --I do carry one, yes sir. --Show me!

  • --You never know. And I seem to use it a lot." --Let's see.

  • --It's a small one. --So I'm going to give you a test. Um what is under Nitrogen on the periodic table?

  • --Nitrogen is 7. --Yes.

  • --Well I have to think a second. "Sulfur."

  • --No you're wrong. Close, you're one off. --That's why I carry it.

  • --It's Phosphorus. --Oh Phosphorous, Phosphorus. 15.

  • --Phosphorus is 15? -- Yeah, you have to add 8 at that point.

  • See that's why I carry it. I can't remember. So it's

  • seven plus 8. 15, Phosphorus. Okay. There's there's a pattern there. I get it now.

  • At the turn of the 19th century, electricity was all the rage.

  • people were busy making batteries and connecting them to just about

  • anything to see the reaction. Electricity was like a new kind of fire.

  • One of the great battery junkies of the day was Humphry Davy, the self taught English chemist.

  • In 1807 Davey was performing a battery experiment in his lab.

  • He melted some potash; a mineral found in the ground,

  • that also forms in the ashes of wood. Chemists had speculated that potash was a compound

  • of several elements, but had not been able to prove it. Davy wanted

  • to see if electricity might provide the answer.

  • He ran some wires from one of his biggest batteries to the melted potash.

  • Pure Potassium began to emerge. Davy had discovered the power of electricity to react with chemicals and transform them.

  • Eventually electrochemistry led to the rise of the

  • aluminum industry, the production of semiconductors, solar panels, LED displays, even rechargeable lithium batteries.

  • In the 1850s Robert Bunsen and his research collaborator Gustav Kirchhoff

  • conducted a series of experiments to determine why substances

  • emitted specific colors when placed in a flame. The color they determined, indicates what

  • elements are present in the substance. For example, if Sodium is

  • placed in a flame, they observe shades of yellow.

  • Copper, shades of green. Strontium, shades of red.

  • That was a good one.

  • While watching the experiments Kirchoff was reminded of how a prism spreads light into a rainbow of colors.

  • So, using a prism and the pieces of a small telescope Bunsen and Kirchoff built the first spectroscope,

  • an analytical device they hoped would help them see the spectra

  • coming from heated substances. And it worked. As an element

  • was put into the flame of a bunsen burner, the light from the heated substance passed

  • through the prism of the spectroscope where it then spread into a

  • ribbon-like spectrum of colors, riddled with dark lines. The combinations

  • of bright colors and dark lines were like barcodes, indicating what atoms were present.

  • When burned, each element produced a completely unique spectrum.

  • Using their spectroscope, Bunsen and Kirchoff were able to discover two new elements; Cesium and Rubidium.

  • One day Bunsen and Kirchoff decided to test their invention with sunlight.

  • It produced a spectrum that featured two lines that were identical to those in the spectrum

  • produced by sodium. Bunsen and Kirchoff had discovered the presence

  • of sodium in the sun 93 million miles away.

  • Suddenly scientists had a tool to help them study the chemistry of the heavens.

  • [Lift off. We have lift off.]

  • Today the legacy of this great discovery lives on in the exploration of space.

  • A form of spectroscopy is being used to study the

  • atmospheres of planets, to search for signs of water. Signs of life.

  • Our next great discovery is the story of Joseph Thomson and the electron.

  • ["Here we are."] --So everything that we can see is made of chemicals.

  • --That's right --What's the future?"

  • --And they're all bonded through electron interactions. --Thank goodness.

  • "To find out about it I paid a visit to Harvard University.

  • Dudley Herschbach is a professor here and winner of the 1986 Nobel Prize in Chemistry...

  • for his research into the dynamics of chemical elementary processes.

  • --So Thomson discovered the electron. --Well it is of course said that way, but he didn't discover it in

  • the sense that he said, "Eureka! I've got this thing. Here it is." He did an experiment

  • that allowed him to measure the ratio of the charge, the electric charge, the

  • mass and then later is able to get a rough measurement

  • of the charge and therefore show the mass was very very small.

  • It was about one two-thousandth's of the mass of the lightest known atom. The Hydrogen atom.

  • So it showed that he could extract an experiment, a very small

  • piece of an atom. Well that was a tremendous shock.

  • --Pun intended. --Yes, yes...electrical piece from an atom.

  • It was a very small part of the atom.