100 Greatest Discoveries

For us, life unfolds on human scales.

Miles.

Feet.

Inches.

But beneath the surface of things is another realm, a billions 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 is just nothing more beautiful than it.

This is the realm of chemistry.

And these are its 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 makeup 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 eighteenth century

clergy man 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 in the Chemical Heritage Foundation in Philadelphia Pennsylvania.

Priestley wrote and wrote and wrote on every subject that you have thought of.

He wrote about history. He wrote about religion. He wrote about politics.

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 simultaneously a liquid and metal.

And that’s just crazy, I mean, whoever heard a liquid metal.

And so it was really puzzling what is this thing and people were fascinated by it, and so they wanted to explore it.

And of course the other thing 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, 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 dose is takes a burning glass to heat the lens.

He focuses it on this orange powder, the mercuric calcs.

He heats it, changes into this metal mercury and a gas comes off.

But Priestley doesn’t really realize what it is that he has 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 was 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.

He’s fascinated by the report on the new air, decides to repeat the experiment.

He has lots of apparatus, better apparatus. He is 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 the whole script of chemistry.

And he creates a list of elements that we still use today.

...Oxygen, hydrogen, sulfur.

You can correctly say that Priestley discovered oxygen.

But Lavoisier invented it.

So, with Priestley’s experimental work on gases, with the discovery of oxygen,

And with Lavoisie's articulation of the system of language.

We have the whole conceptual scheme on which 19th century’s academic works is built

20th century’s industrial innovation. We have pharmaceuticals, we have biotechnology, we have cell phones.

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 19th 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 relatively 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.

And we know it as atomic weights, but it was ultimate particles.

So, he used the word atoms. He used the word atoms.

And the idea of atoms 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.

Form 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 this is enormously simple system and Dalton thinks very simply, very visually.

Here are the elements. Here are the weights 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. 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 18 hundreds, 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 volumes 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 19th century.

When many chemists believed that organic substances from organisms or living things.

Were somehow different from inorganic substance, from nonliving things.

But that was about to change.

In 1828, Frederick Waller was working in his lab, when something caught his eye.

Waller had placed two inorganic chemicals in a beaker, potassium cyanate and ammonium sulfate.

Now, when you looked at the beaker, it contained a gram of small, white, needle shaped crystals

what made this remarkable was that Waller thought he had seen exactly the same crystals once before.

But with an important difference. Those crystals had been organic.

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

To make sure he wasn’t mistaken, Waller 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 an inorganic substance.

Later he said in a personal letter in a paper he wrote about that

I had made urea without a kidney.

And 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 that 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 19th century, chemists could use them to help illustrated 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 seem 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 were puzzling about it, offering different explanations.

And one of them, August Kekulei sitting by the fire one of evening, falls asleep.

And starts to dream about a snake. And if you think about the snake what Kekule dreams of is a snake catches its own tail.

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

The 6 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 in their molecules

with Kekule’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 is a recipe for new drugs, new medicines, new understanding.

To go back at time in Dalton’s day, couple of hundred compounds, soon it's a couple of thousands,

soon it's ten thousand, it's astonishing, soon it's a hundred thousand. Last year, fifteen million new compounds were registered.

All built on this simple template. This is the work of genius.

In 1869, a Russian chemistry professor named Dmitry Mendeleyev was writing a text book for his students.

When he began to wonder how he 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, its typical properties and its similarities to other elements.

He then laid the cards out like a game of solitaire.

And began to arrange 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.

Mendeleyev had discovered the periodic table of the elements a map showing how all the elements related to one another.