The simplest approach to chemistry is to start basic.

Not basic as in acids and bases, ha-ha…sorry, bad chemistry joke.

I mean basic as in, what the heck even is chemistry?

I admit that I’m better versed in astronomy than chemistry. I’ve studied chemistry for exactly one year of my life—last year, 12th grade. Astronomy, on the other hand, has been my strong suit and my passion for several years.

For me, these Wednesday posts are like a refresher course. I don’t actually remember everything I’ve learned. Good thing I bought a copy of the textbook.

So, I’ll start simple—because chemistry is the study of breaking complex things down to the simplest bits possible. It’s the opposite of astronomy. Astronomy studies huge, mind-blowing phenomena. Chemistry, on the other hand…is mind-blowingly small.

It’s the study of matter.

We begin with…okay, let’s say, a golf ball.

Take a wild guess: what do you think this golf ball is made of?

In fact, what do you think anything is made of?

Yup, you guessed it: matter.

Everything is matter. It is defined as anything that has mass and takes up space.

So, allow me to anticipate your next question: What is mass?

Slightly more complicated question…especially since it requires an understanding of matter.

The mass of an object is the amount of matter it contains.

Ugh…I just hate definitions that include crazy science terms, don’t you?

Never fear: there is a simpler definition of matter. It’s just stuff. A mug is matter. Chocolate is matter. The smallest dust speck is matter and the tallest skyscraper is matter. In fact, speaking of which…a planet is matter, and so is a star.

I just can’t help delving into the astronomy stuff…

What’s mass, then? The amount of stuff an object contains. Not how much it weighs or its diameter or anything like that. Mass is a measure of how much stuff is in an object. Let me put it in a different way: if you have a specific volume, then more mass equals greater density—more stuff being squeezed into the same space (volume).

If chemistry is the study of matter, you can probably imagine that we’ve only scraped the surface. There is a whole field of science that studies matter. Why? Because there are so many types of matter, and so many things you can do to matter.

Chemistry is, more specifically, the study of matter and the changes it undergoes.

Let’s start with the different ways to describe matter. One type of matter is a substance—matter that has a uniform and definite composition. (Sorry for the textbook definition…I generally try to avoid those.)

Here’s an example of a substance we all know very well:

Believe it or not, this image contains all forms of the molecule H₂O that exist. The water is its liquid form, the ice is its solid form, and the clouds above the land are its gaseous form.

I chose water because (1) it’s an extremely important molecule in all of science and (2) because, face it, we’re all familiar with it. You’ll be hearing a lot about water in subsequent chemistry posts.

Water is a substance. No matter how much of it you scoop out and pour into different containers, it’s always going to be the same thing: H₂O. It will always be composed of two hydrogen atoms and one oxygen atom. That formula will never change.

Lemonade, on the other hand, is not a substance. But I’ll be talking more about lemonade later.

Substances also have physical properties. What I mean by that is what happens to the matter when the outside conditions change.

The difference between physical properties and chemical properties—which I will also talk about later—is that physical properties don’t change what the object is.

For example, an apple is still an apple even if you cut it or bite into it. Okay, it’ll be in a few pieces (some of which are in your stomach), but all of it is still an apple.

What happens inside your stomach is another story—and that involves chemical properties.

We are familiar with the physical properties of water. It is clear and odorless. Hardness depends on its current state, as does density. Its melting point is 0℃ and its boiling point is 100℃. (The Celsius scale is based off of water’s properties.)

We are also very familiar with water’s states—or, at least, I hope so.

Here’s the funny thing about water—its liquid and gas forms behave the way we expect them to, but ice is very contrarian.

Have you ever noticed that ice floats?

Ahem. Ice is a solid. It’s not supposed to float.

Do cars float? Or steam engines? Or houses? Or…iron chains?

No.

Normally, the solid state of any substance is more dense, and therefore less floaty, than the liquid state. Similarly, the liquid state is more dense and less floaty than the gas state.

Water does something strange, and it happens at the molecular level. You can be sure I’ll talk a lot more about it later.

The basic idea with states of matter, though, is how close the molecules within a substance are to one another.

Another difference between states of matter is how fast the molecules are moving, but we’ll get into that stuff later.

Here, imagine that two blue circles stuck together are a molecule. Any substance—such as oxygen—that exists as two of its own atoms stuck together could be represented here. (Although I can’t think of oxygen as anything but a gas.)

In the solid state, atoms are locked tightly together. They also vibrate a little in place. If they were completely still, the object would have reached the temperature of absolute zero, and that’s just theoretical. Not something that actually happens.

In a liquid, the particles are free to move about a bit. They slosh around and conform to the shape of their container. But they’re still trapped inside.

Gases are particularly contrarian. They like to defy their enclosures. Earth’s atmosphere would escape out to space if our planet didn’t have gravity holding it all in.

Here’s a cool fun-fact to conclude this post. Because the force of gravity decreases and gets weaker the farther out you get, the atmosphere is thinner—less of it held in—up on mountaintops.

For the same reason, Earth doesn’t have a set boundary to its atmosphere…it just keeps going, getting thinner and thinner until there isn’t any left at all.