State of matter

Three states of matter that can be seen in everyday life: solid, liquid, gas

Kids talk about science

What are you thinking about, Sara?

I'm thinking about how it's boiling hot outside... and yet your heart is still ice cold.

I’m not sure what you meant by that, but hey—that actually gave me a great idea for today’s science topic: states of matter!

Ugh, if we really have to...

Mark:You just mentioned ice. Are ice and water the same thing?

Sara: Hmm, not really. I mean, water is liquid and ice is solid, but they can turn into each other pretty easily. So... I don’t know.

Mark: Let me ask it in a different way. Are ice and water made of the same substance?

Sara: They’re made of the same particles—we call them molecules. In this case, both water and ice are made of H₂O molecules. So yeah, I guess that means they’re the same substance.

Mark:That’s right, Sara! If they’re made of the same particles, then ice, liquid water, and water vapor are all the same substance. They’re all made of H₂O molecules.

Sara: Then why don’t they look the same, if they’re made of the same stuff?

Mark:Good question! It’s because in these three forms—what we call the states of matter—the particles (in this case, water molecules) are arranged differently. They’re spaced out differently and move at different speeds.

Sara: Okay… now I’m lost. Draw it for me.

Mark: I’ll explain it first—then you try drawing it!
In the solid state, the particles are packed tightly together. There’s very little space between them and they move very slowly. That’s why solids usually take up less space than liquids or gases. In the liquid state, the particles move a bit faster, so they’re a little farther apart and not as strongly connected. And in the gas state, the particles are moving really fast—in all directions! They bounce off each other and the space between them is much bigger than in solids and liquids.

Sara: Ohhh! That actually makes sense. It’s like how hotter things are different from colder ones because their particles are moving faster. The hotter it gets, the faster they move?

Mark:Exactly! And the faster the particles move, the more they crash into each other—and the more chaos there is. That’s why the state of a substance depends on the temperature. When we heat up a solid, the particles move faster and faster, the connections between them get weaker, and eventually the solid “breaks apart” and becomes a liquid.

Sara: Wow, Marko—your heart may be cold, but your words and ideas are definitely flowing! 😄

Key Science Concepts

It looks like Sara understood the differences between the three states of matter really well and drew this table to help you understand them too.

Solids	Liquids	Gases

Definite shape and volume	Definite volume, but takes the shape of the container	No definite shape or volume
Particles vibrate in fixed positions	Particles slide past each other	Particles move rapidly and spread far apart

A state of matter: form in which a substance exists — whether it is a solid (like ice), liquid (like water), or gas (like steam).
It depends on how the particles in the substance behave: how close they are, how freely they move, and how much energy they have.
Heat: is energy made by moving particles. When particles move faster, the substance feels hotter.

Science Fun Facts

Most people learn that matter exists in three states — solid, liquid, and gas. But there’s more! Scientists have discovered other, less common states of matter. One of them is called plasma — and it’s actually the most common state of matter in the entire universe!

So, what is plasma?

Plasma is a super-hot gas where the atoms have been “ripped apart.” The electrons break away from the atoms, so instead of neutral particles, you get a mix of positively charged particles and free electrons. This makes plasma able to carry electricity and react to magnetic fields.
You can find plasma in lightning, neon signs, and even in the Sun and all the stars. So while we don’t see it much on Earth, it's literally lighting up the universe!
And if that’s not wild enough — there’s also a super-strange state called Bose–Einstein condensate, where matter acts like a single super-atom when it gets unbelievably cold. We're talking colder than outer space!

Quick Science Quiz

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