Chemistry made me CRAZY as a student—because it seemed like a thrown-together subject.
Just a grab-bag of random, unrelated topics.
Even after teaching chemistry for many years, in some ways, I still feel that way.
If you page through a chemistry textbook, it jumps around from the composition of compounds,
elements,atoms, ions, physical properties, chemical properties, types of reactions, energy
changes...It seems like in Chemistry, we study just everything anyone has ever figured out
about how matter behaves.
It’s not nicely organized like Math or Physics or Biology.
I never got the sense of you start with this fundamental thing, and then this follows,
and that leads to this..
This feeling was exacerbated by my freshman-year chemistry class in college, at Caltech.
We didn’t have a textbook.
We had several professors that year, just come in and talk about what THEY thought was
important in Chemistry.
Don’t get me wrong—I learned a lot, but it didn’t help me develop a sense of how
the subject was organized or could be organized.
I had no idea what subject could be coming next, no idea how the topics could be connected
to each other.
Because the subject is so disorganized—You would THINK that means Chemistry is a young
science, but no - that’s not true.
That’s not the reason.
People have been studying chemistry ever since cavemen mixed together pigments to do their
cave paintings.
The “Iron Age,” the “Bronze Age” - we actually named entire historical time periods
after advances in metallurgy.
How long ago do you think gunpowder was invented?
The ALCHEMISTS are probably the closest to what we would recognize as early chemists.
There were the ancient Greeks with their four elements of nature: Earth, Fire, Air, and
Water - and they combined their philosophy with the Egyptians and their mystical rituals
about rebirth, associated with the Nile river and its rich black soil they called Khem.
The Greeks called Egypt KHEMIA.
Then in the 7th century, Egypt was occupied by the Arabs, and they added “al-” to
form the word “al-Khemia” - the black land.
Alchemy was introduced to the West in the 8th century, when the Arabs brought it to
Spain, and eventually it spread as far as India and China.
Sadly, we’ve lost most of the earliest alchemy texts because in the year 391 the Great Library
at Alexandria burned.
But we do have some very interesting writings about alchemy from the Middle Ages.
Those Alchemists got kind of a bad rap as a bunch of kooks.
I don’t think we should sneer at their efforts because they weren’t scientists, exactly.
They were sort of like PRE-scientists.
Alchemists wanted to harness the power of nature and create the legendary Philosopher’s
Stone that would grant them eternal life.
They also wanted to use the Philosopher’s Stone to generate gold and other precious
materials out of less valuable “base matter” like lead.
They were pursuing Transmutation - they thought that substances could evolve, or develop towards
a more perfect state.
That’s the result of observing physical and chemical changes - and that’s where
you start to do chemistry.
The alchemists were doing their best to catalog their observations about how different kinds
of matter interacted, and that’s a scientific impulse—they just weren’t very systematic
about it, and they had a warped sense of logic because mysticism was intertwined in everything
they did.
If the alchemists observed something they didn’t understand, they made up a rule to
explain it - and these rules seem superstitious to us now.
They almost gave personalities to the different metals they worked with, and they thought
that a celestial object, as well as a day of the week, and an organ in the human body
- was connected to each element.
So for instance, Lead was connected to Saturn, and Saturday, and in your body, the Spleen.
Eventually, the work of early scientists or “natural philosophers” (that’s what
they were called in the 17th / 18th centuries) accumulated enough reproducible information
that scholars concluded the aims of alchemy were just not reasonable.
So maybe we should say Chemistry, as we know it, based on experimental evidence, started
around the 18th/19th century.
So can we start there, and describe what Chemistry IS?
Maybe in terms of other subjects we DO have a better handle on.
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Now back to unraveling this hairy problem of What IS chemistry.
Chemistry is often called “The Central Science” because it CONNECTS to many other disciplines.
You can picture it sitting in the middle like a giant hub of science knowledge.
You have physics over here, and physical chemistry.
Biology has biochemistry.
Here’s geology, and geochemistry.
Astronomy/ astrochemistry.
If you want to study these disciplines: biology, geology, astronomy, materials science...the
truth is, you won’t get very far into the nitty gritty unless you know some chemistry.
Of course you can learn some basics.
But you’re fooling yourself if you think you’ll have access to the whole field.
Chemistry is what gives you a more complete understanding, and it’s through a chemical
understanding that you’ll be able to talk with REAL biologists, REAL astronomers - and
not just a textbook written for beginners.
Back when I was teaching, I got in this huge argument with a micromanaging administrator
who tried to tell me it made no difference whether a student had the prerequisite of
chemistry before they took my advanced biology class.
I flatly refused to accept any students into my class who hadn’t studied any chemistry
because, guess what?
At least a third of my class WAS chemistry.
Biochemistry is about the subset of chemicals found in living organisms.
Molecular Biology is about MOLECULES.
How can you teach any real significant biology to someone who doesn’t know what molecules
are and how they behave, chemically?
It would be like saying you can take calculus before you take algebra.
I’m still mad.
I won, obviously, but I’m still mad that someone could be that dismissive of how important
chemistry is.
You see, in many ways, the study of biology is an EXTENSION of the study of chemistry.
All of life - every bit of our bodies - is made up of chemical compounds.
This is true of all living things.
Those chemicals interact with each other, sticking together to make larger compounds
or breaking apart to make smaller modules that can be reused, or exchanged for energy.
All the essential biological processes - cell reproduction, glycolysis, cellular respiration,
photosynthesis - these are all built up from a set of chemical reactions and exchanges
of chemical energy.
If you don’t understand the chemistry of biological molecules in plants and animals,
you won’t understand how these organisms reproduce, develop, grow, you won’t understand
diet or nutrition or hormone signalling, how we taste and smell, and see, or how animals
are able to move by contracting their muscles, or how the neurons in your brain function…
So, even if you consider yourself a biologist, or you want to major in biology, or medicine
for that matter, you’re not going to get very far unless you get a strong background
in chemistry.
I personally am a MOLECULAR biologist and so this was a big leveling up step for me
- to respect what I had to learn from chemistry before I could move forward in my chosen field.
Now let’s talk a little bit about how chemistry is relevant in other subjects you might be
interested in.
When kids are first interested in astronomy, we give them a telescope, which is a lot of
fun, but most modern astronomy isn’t about looking through a telescope with your naked
eye.
There’s a fundamental connection between chemistry and astronomy, and it includes how
elements are generated in fiery stars, or on the other side of the story, how molecular
clouds could give rise to stars.
You’ll hear a lot about “spectral lines” in astronomy - every element and molecule
emits light at specific frequencies, so we can use chemical spectrographs to identify
the composition of stars and other celestial objects.
Geology is another field that is basically chemistry at its heart.
Rocks and minerals ARE chemicals.
So you see geologists using a lot of the tools of chemistry in their work.
They have to examine the chemical composition of samples in order to understand hardness
and erosion.
There are gradual chemical changes as rocks and minerals interact with the environment
and break down over time.
The study of radioactive elements is essential for dating, like carbon dating.
Engineering is probably the most blue-sky area for extensions of chemistry.
Engineering is all about using science and math to solve problems, and we NEVER run out
of problems.
A big area of research right now is ENERGY - can we conserve energy or produce more energy?
Can we do a better job capturing solar energy and can we make more efficient batteries for
storing energy?
Chemists will help solve those problems.
A lot of engineering depends on how well you understand the materials you have to work
with.
What kind of stress can they withstand.
Are they going to break down when they come in contact with a cleaning solution?
Is it safe - chemically inert?
or is it volatile?
Chemistry is what lets you understand a material’s strength, appearance, whether it’s combustible,
and so on.
And, if you’re not satisfied with the materials that are out there, you can make new ones
by using applied chemistry, or chemical engineering.
Now Physics is a really interesting case.
Physics and chemistry are SO interdependent.
When I study chemistry, I find myself falling back on a lot of physics concepts to understand
why the chemistry works.
Why are particles moving this way, what’s the force of attraction or repulsion, why
is this form more stable...So even though we call chemistry the “Central Science,”
I might argue that it all really starts with physics.
You don’t need to study ALL of physics to understand chemistry, but it’s a good idea
to get familiar with the basic concepts, and then circle back later.
Similarly, you don’t need to study ALL of chemistry to understand physics.
But maybe start with atomic structure and in particular the behavior of electrons.
Here’s how I would actually suggest people study the sciences:
Physics first - on one level.
Basic, conceptual physics that doesn’t take much math.
Then Chemistry.
Then Biology.
Then, circle back to Physics and learn more, including the calculus.
Then branch out into Astronomy, Engineering, Materials Science - whatever tickles your
brain.
But set yourself up for success by understanding how interrelated all of these disciplines
are.
Chemistry will help you get there.
I think it wasn’t until I TAUGHT chemistry that I finally got a handle on what we know
in the subject, and what we’re still trying to figure out.
Even as an instructor, it’s challenging to know what to include in a given class,
and what to leave out.
If you look at different college catalogs, you’ll see the chemistry subjects broken
up in different ways.
If you ask a chemist “How many Branches of Chemistry are there?”
Some say 5, some say 6…I saw one list that said 10 - It depends on how you count them.
The most common answer I hear is 5 branches of chemistry: Organic Chemistry, Inorganic
Chemistry, Physical Chemistry, Analytical Chemistry, and Biochemistry.
Organic Chemistry is the study of chemical compounds that contain carbon.
This is really important for understanding life on Earth, because all living things have
carbon as the backbone of their molecules.
So organic chemists study the structure and properties of all these carbon-based molecules
- and there’s all kinds of applications in biotechnology, petroleum, plastics...
Inorganic Chemistry studies the rest of the chemical compounds.
Everything that’s inorganic, or nonliving.
That doesn’t mean these kinds of chemists NEVER study anything containing carbon - there’s
some crossover.
Industry applications include things like making fertilizer, creating chemical sunscreens,
studying pigments for paint…
Physical Chemistry is when you use Physics to explain chemical phenomena.
So, think about how we have physics equations to describe how objects move, forces of attraction,
wave behavior.
New physics emerges when you try to extrapolate to describe the physical behavior of tiny
things like atoms and molecules.
And of course, what the physical chemists discover gets incorporated into all the other
branches of chemistry, because everyone has to obey the laws of physics.
Analytical Chemistry is maybe the most quantitative of the chemical disciplines.
Take any chemical property, and figure out how to measure it and track it, and compare
it.
If you like fiddling with lab equipment - like mass spectrometers and bomb calorimeters and
chromatographs, and titrating!
- then maybe analytical chemistry is for you.
Biochemistry is the study of the molecules of life, and it relies on the same techniques
that other chemists use along with some specialized ways of studying things, for instance, the
exact 3-dimensional shape of proteins when they’re properly folded up, and the dynamics
of how they interact with each other, and how enzymes catalyze reactions, things like
that.
By the way - I made another video “What is Biochemistry” if you want to learn more
about what that field covers.
Keep in mind - this separation of 5 disciplines in chemistry is so arbitrary.
You can already see, there’s a lot of overlap between these 5.
And then there are a million specialized fields.
You can add Theoretical Chemistry, Forensic Chemistry, Environmental Chemistry, Nuclear
Chemistry...
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A lot, I’m sure, you’ve learned a lot.
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Thanks for watching.