Stated Clearly presents
What is a molecule
Though textbook definitions of the word molecule can sometimes be a bit complicated
A molecule can be loosely thought of as a group of atoms stuck together
Usually through chemical bonds
Here we see a single hydrogen atom traveling through the cosmos
It's made of one positively charged proton in its nucleus
and one negatively charged electron
If our lone hydrogen atom happens to pass close enough to another lone hydrogen atom
their electrons, which are attracted like magnets to protons
can pull the atoms toward each other until they collide and stick together
The two atoms now share each other's electrons in what is called a covalent chemical bond
What were once two individual hydrogen atoms have now formed a single hydrogen molecule
This bond is not permanent
with enough heat or due to interactions with other molecules
the hydrogen atoms will readily separate once more
Different types of atoms can form different numbers of chemical bonds
A hydrogen atom can only form one covalent bond at a time
If a third hydrogen atom were to collide with a hydrogen molecule
It would simply bounce off or if it hits hard enough, or in just the right place
it can trade spots with one of the existing atoms
An oxygen atom can typically form two bonds
A carbon atom can make four
An argon atom won't usually bond with anything
Even though possible bond numbers per atom are pretty small
huge molecules can form if bonds happen to be properly arranged
For example, even though hydrogen can only form one bond
a standard water molecule is always made of three atoms
This is possible because oxygen which can form two bonds
forms just one bond with each hydrogen atom
A single molecule of the sugar known as glucose
is made of 24 atoms, a special arrangement of carbons, hydrogens and oxygens
A typical fatty acid in the human body may vary in length
this one here is made of 38 atoms
And finally a single protein, depending on the type
can contain over half-a-million atoms all covalently bound together
The molecular models that I've been showing you here so far are what we call space-filling models
They show us roughly what the outside of each atoms electron cloud looks like
and different types of atoms have been assigned different colors
when we look at real molecules with a scanning tunneling microscope
they look pretty similar to these space-filling models,
but the atoms are not color coded and their edges are fuzzy
That blur is partly due to the microscopes limitations
and partly because atoms actually do have soft boundaries
When looking at complex molecules
space-filling models and especially actual images of real molecules
can be a bit confusing to look at, which atoms are bound together
which atoms are just close to one another
for this reason, chemists sometimes use what are called ball and stick models
these highlight the bonds between atoms
the skeleton of a molecule instead of showing each atoms outside surface
In 2009, Dr. Leo Gross and his team at IBM,
discovered a way to take actual skeletal pictures of molecules.
This is not a drawing
This is not a computer-generated model.
This is an actual scan of a real molecule
Amazingly atomic theory was allowing scientists to draw molecules with surprising accuracy
over 100 years before this image was finally taken
That's quite a testament to what good scientific theory can do
When atoms come together to form a molecule
the molecule vibrates between its bonds in a regular pattern
You can think of the bond as a bouncing spring
This is because the protons and the nucleus of each atom repel one another
while the shared electrons in each bond pull the atoms back together
The vibrations we find in molecules are the result of a perpetual tug-of-war between these two forces
if you add more energy to a molecule with heat or light
The amplitude, the length of each vibration will increase
without changing how frequently each vibration completes its cycle
This means the bouncing spring stretches further and the atoms move faster
If you add enough energy the bond will eventually break
Scientists are fascinated by molecular movements and want to understand them better
These vibrations have a huge number of potential applications in chemistry, medicine,
electronics and computer engineering
Watchmakers for example use the unchanging speed of molecular vibrations
to build watches that keep nearly perfect time
In a quartz crystal, bond vibrations between its atoms resonate causing the entire crystal
when cut to the right size and shape to oscillate microscopically at 32,768 times/second
Inside each quartz watch is a tiny crystal along with electronics that can count the crystals vibrations
This then tells the second hand precisely when to move
In April 2019 in the journal Nature,
Joonhee Lee and his colleagues from The Center For Chemistry at the Space-Time Limit
have published the first images ever taken
of molecular vibrations at the atomic scale
Though these images may seem a bit strange to you and I,
they show researchers exactly how this molecule bends and pulses between its bonds
Scientists can use images like this to build accurate models
predicting exactly how different molecules will behave under various conditions
With this new precision knowledge, engineers are working on solar panels that generate far more energy,
computer chips that do not overheat
and researchers are planning to use this imaging technology to better understand our own DNA
Even in the field is thoroughly studied this chemistry. The old saying is still true
Somewhere, something incredible is waiting to be known
So in summary, what is a molecule?
A molecule can be described as a group of atoms stuck together through chemical bonds
different types of atoms can form different numbers of bonds
Molecules can be as small as two atoms stuck together
or as is the case for some proteins
They may contain over half a million atoms, all covalently bound together
Recent advances in molecular imaging are now letting us take snapshots
of molecular vibrations at the atomic scale
I'm John Perry and that as a molecule Stated Clearly
This animation is part of an intro to chemistry series
sponsored in part by the National Science Foundation and the CaSTL Research Center
That's Chemistry at the Space-Time Limit.
It was also funded in part by my wonderful supporters on patreon.com/statedclearly
Thank you. I could not do this without you
Along with this video series, CaSTL and The National Science Foundation
have funded the creation of an amazing online video game called Bond Breaker
In the game, you are a proton
and you go on a bunch of little adventures learning powerful concepts
in chemistry and nuclear physics as you go
I've shown you clips of the game before but a new version was just released and it is wonderful
Go check it out at TestTubeGames.com
There is a link down in the video description
Not only will it teach you new things about chemistry and atomic physics
It's also almost too fun to play
Today I went to play it for just a few minutes so I could record my screen
and show you what the game looks like
But I ended up playing for over an hour.
So kudos to Andy at Test Tube Games, you have done an amazing job
Teachers use this in your classrooms, it's free