FLASHCARDS! Avocados + Avogadro's Number = A Delicious Molement

On this Flashcards Friday episode, Gabrielle serves up a tasty blend of chemistry, humor, and history. Coinciding with National Avocado Day, this episode dives into the life and legacy of Amedeo Avogadro, the 19th-century chemist behind the foundational theorem of gas volumes, and how his name unexpectedly became linked with everyone's favorite green fruit. From moles to molecules to memes, Gabrielle brings the science home, one chip at a time.

🌱 3 Things You'll Learn in This Episode:

1. Who Amedeo Avogadro was and what his theorem states about gas volumes.

2. How the mole (6.022 × 10²³) became a central concept in chemistry.

3. Why Avogadro’s legacy lives on in both labs and lunchrooms (thanks to Avocado Day puns!).

🔗 Resources Mentioned:

National Avocado Day Info – National Today

Avogadro’s Law – LibreTexts

History of the Mole Concept – American Chemical Society

 🔗 Explore more on our website: mathsciencehistory.com
📚 To buy my book Hypatia: The Sum of Her Life on Amazon, visit .css-j9qmi7{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:row;-ms-flex-direction:row;flex-direction:row;font-weight:700;margin-bottom:1rem;margin-top:2.8rem;width:100%;-webkit-box-pack:start;-ms-flex-pack:start;-webkit-justify-content:start;justify-content:start;padding-left:5rem;}@media only screen and (max-width: 599px){.css-j9qmi7{padding-left:0;-webkit-box-pack:center;-ms-flex-pack:center;-webkit-justify-content:center;justify-content:center;}}.css-j9qmi7 svg{fill:#27292D;}.css-j9qmi7 .eagfbvw0{-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;color:#27292D;}

Episode Transcript

(00:02):
It's Flashcard Fridays here on Math Science History, where we unpack big ideas into a
flashcard.
I'm Gabrielle Birchak, your host, your guide through math and science history, and your
occasional punslinger.
And today, well, I just could not resist.
But first, a quick word from my advertisers.

(00:25):
Yesterday, July 31st, was officially Avocado Day.
And today, well, it's only fitting that we turn our attention to one of the most deliciously
misunderstood concepts in chemistry, Avogadro's Theorem.
Or as I like to say, it's not just about the guacamole, it's about the mole.

(00:48):
So settle in.
Whether you're munching on avocado toast, my favorite, or just curious about how tiny
particles fill up space, we're about to explore how a 19th century Italian chemist
gave us one of the most fundamental ideas in chemistry, an idea so powerful, it helps

(01:09):
us count the uncountable.
And speaking of uncountable, it is only appropriate that the man himself who came up with this
theorem was Lorenzo Romano Amadeo Carlo Avogadro, Count of Quaregna and Cereto.
Avocadro, I'm sorry, Avogadro, see, now I'm stuck on this.

(01:32):
Okay, Avogadro was born in Turin, Italy in 1776.
Avogadro studied law originally, like many aristocratic sons of his time, but quickly
found himself drawn to the natural sciences.
And by the early 1800s, he was neck deep in physics and chemistry, working at a time when

(01:52):
the structure of atoms, molecules, and gases was still very much a mystery.
The scientific world was just beginning to grasp that gases were made of individual particles.
But how many?
How did they behave?
And how could we predict their properties?
That's where Avogadro enters the scene.

(02:12):
So he had this big idea.
In 1811, Avogadro made a bold proposal, one that would take nearly 50 years to be accepted.
He suggested that equal volumes of gases at the same temperature and pressure contain
equal numbers of molecules.
This deceptively simple statement is what we now call Avogadro's hypothesis, though

(02:37):
it eventually evolved into what we now call Avogadro's law.
So let's break that down.
Imagine you have a balloon full of helium and another full of hydrogen, both at the
same size, the same temperature, and the same pressure.
According to Avogadro, both of these balloons contain the same number of gas molecules,

(02:58):
regardless of the type of gas inside.
So let's let that sink in.
He was saying that the volume of a gas is directly proportional to the number of particles
inside it, provided we keep the temperature and pressure steady.
This was huge.
Before Avogadro, chemists were trying to figure out why gases didn't always behave how they

(03:20):
expected.
Why did some gases weigh more but seem to take up the same space?
His theory brought clarity.
So now we go on to the mole.
Not the animal, not the spy, but the count.
Here we go.
I'm going to try and say this without laughing, but here's where things get really spicy.

(03:44):
Avogadro's idea eventually led to the creation of one of the most central units in chemistry,
the mole.
No, not the critter digging tunnels under your lawn and not the double agent in a Cold
War spy movie.
I'm talking about the mole, the unit that helps chemists count particles that they cannot

(04:05):
see.
Just as a dozen means 12, a mole means 6.022 times 10 to the power of 23 particles.
This is known as Avogadro's number.
That's 602 sextillion things.
Yes, a sextillion, not a million, not a billion, not a trillion, not a quadrillion, not a quintillion,

(04:27):
but a sextillion.
That's 23 zeros in Avogadro's number.
So picture this, if you had one mole of marbles and you tried to spread them evenly across
the surface of the earth, you would wind up with a marble layer several miles thick.
If you gave every person on earth a mole of dollars, each person could buy the planet

(04:52):
and still have cash left over for a lifetime supply of guacamole.
So why does the mole matter?
What's the point in having a unit that represents such an enormous number?
Well, chemistry happens on a molecular level and molecules are tiny.
You can't count them by hand and weighing them individually would be impossible.

(05:17):
So the mole allows chemists to predict how substances react with each other.
They allow chemists to balance chemical equations.
They calculate masses of compounds and they allow chemists to scale up reactions from
the lab to industry.
It's a lot like how we go from mixing vinegar and baking soda in a volcano model to manufacturing

(05:39):
medication and rocket fuel.
So think of it like a chemist's Rosetta Stone.
It connects the invisible world of atoms to the measurable world of grams, liter and pressure
gauges.
So let's talk about Avogadro's law in action.
Let's say you have a syringe of gas.
If you add more gas molecules, keeping temperature and pressure constant, your volume increases.

(06:05):
That's Avogadro's law in motion.
You would think that such a useful idea would have made Avogadro famous in his lifetime,
but it did not.
Avogadro published his hypothesis in 1811, but it wasn't widely accepted until the 1860s.
A major reason?
Communication.
Avogadro was isolated from many scientific circles.

(06:27):
He wasn't part of the Parisian or London elite, and his ideas were really ahead of their time.
And it wasn't until an Italian chemist named Stanislao Cannizzaro revisited Avogadro's
hypothesis at a chemistry conference in Karlsruhe in 1860 that the theory finally gained traction.
In fact, the concept of the mole as a unit wasn't formalized until the 20th century.

(06:55):
The term itself came from the German word mole, which means heap or pile.
Avogadro died in 1856, never knowing the impact his name would eventually have in textbooks,
classrooms, and yes, puns.
So let's return to that delicious coincidence.

(07:17):
Avogadro's name sounds just like avocado.
It's such a close match that every chemistry teacher has made a joke about it at some point.
Some better than others, but nevertheless, I always laughed, and it's all in good fun.
But here is the real takeaway.
Both avocados and Avogadro remind us that names and numbers can be sticky.

(07:41):
Sometimes we glaze over them, but behind every funny pun is a nugget of understanding.
And when you remember Avogadro's theorem the next time you see a guacamole bowl,
you're doing exactly what science history is all about.
Connecting the dots, making knowledge memorable.
So let's flip through our mental flashcards.

(08:04):
What does Avogadro's theorem state?
Well, it states that equal volumes of gases at the same temperature and pressure
contain equal numbers of molecules.
Flashcard number two.
What is Avogadro's number?
It is 6.022 times 10 to the power of 23 particles per mole.

(08:27):
That's 23 zeros after the number 6022.
Flashcard number three.
Why is the mole important in chemistry?
Well, it lets scientists count atoms and molecules in measurable quantities.
Finally, one last mole-ment.
Whether you're a student, a science fan, or just someone who enjoys a good pun with your guac,

(08:51):
Avogadro's theorem is a shining example of how one clear idea,
when nurtured by time, evidence, and communication, can transform an entire field.
Amadeo Avogadro probably never tasted guacamole.
He likely never met an avocado because avocados were first grown in Central America

(09:12):
and were introduced to Italy in the 20th century.
Much like the avocado traveled far distances to arrive in Italy in 1909
to make our cuisines much more delicious,
Avogadro's name traveled across centuries and disciplines,
from gas laws to grocery stores,
all to make the invisible world of atoms feel just a little more tangible

(09:35):
and, like the avocado, a lot more memorable.
So today, on the day after Avocado Day,
let's raise a chip and say here's to Avogadro,
the only chemist who could turn a gas law into a punchline and a pun into a legacy.