Learn Science »

The Three States of Matter - Educational Discussion

The Three States of Matter

Gertrude’s favourite subject is science. She is fascinated by how it explains the natural world. In particular, she is intrigued by the composition of things around us. One day she found her science teacher, Mrs. Thomson at the cafeteria having coffee. She thought this was an opportunity to discuss some science.

Gertrude: Good morning Mrs. Thomson.

Mrs. Thomson: Very good morning, Gertrude. What’s up?

Gertrude: Do you mind if I bother you a while? I have a few things to clear up about our science lesson yesterday.

Mrs. Thomson: Of course! No problem. Ask me what you want.

Gertrude: You told us that matter can exist in three states, right?

Mrs. Thomson: Yes. Solid, liquid and gas.

Gertrude: So how about the composition of matter in these three states? Are the particles that make up matter the same in these three states?

Mrs. Thomson: Yes, of course. There are various theories about this. According to the particulate model of matter, matter is made up of particles. The arrangement of these particles is different in the three states of matter.

Gertrude: That is interesting! How about solids? How are the particles arranged in solids?

Mrs. Thomson: The particles in solids are very closely packed together.

Gertrude: That makes sense.

Mrs. Thomson: Yes, they are also strongly attracted to each other. Besides, they are arranged in a fixed, regular pattern.

Gertrude: So, particles in solids cannot move at all?

Mrs. Thomson: Their only movement is vibration in their fixed position.

Gertrude: I see. Interesting!

Mrs. Thomson: Yes, and as you know, a solid has a definite shape. It also has a definite volume.

Gertrude: Ok. But I guess it will be different in the case of liquid and gas, right?

Mrs. Thomson: Yes Gertrude. Your guess is right. In liquids, the particles are still attracted to each other, and also packed closely together. However, they are not arranged in a fixed, regular pattern.

Gertrude: That is cool!

Mrs. Thomson: Yes, and what is more, these particles can move over short distances in liquids.

Gertrude: Oh, I see!

Mrs. Thomson: As you may guess, because of this, a liquid does not have a definite shape.

Gertrude: Yes of course. But does a liquid have a definite volume?

Mrs. Thomson: Yes, it does.

Gertrude: I am guessing that it is going to be very different in the case of gases, right?

Mrs. Thomson: You are right. In the case of gases, the particles are weakly attracted to each other.

Gertrude: Let me guess. They are not arranged in a fixed, regular pattern too.

Mrs. Thomson: Right. The particles in gases can move freely in any direction.

Gertrude: Is that the reason a gas has no definite shape or volume?

Mrs. Thomson: Yes! You are a very smart girl! It is a joy to teach science to students like you.

Gertrude: Thank you, Mrs. Thomson. That means a lot to me.

Mrs. Thomson: Do you want to know more about states of matter? The topic is endlessly vast.

Gertrude: Yes, Mrs. Thomson. I have always wondered about the way gases move. For example, how does a scent quickly spread across the room? At home, when there are guests, my mother sprays air freshener if the room does not smell good. It takes only a few seconds for the whole room to smell good.

Mrs. Thomson: The spreading of smells is because of the movement of gas particles. The gaseous particles of the scent move about randomly in all directions. This allows them to spread and fill the room.

Gertrude: That is very interesting!

Mrs. Thomson: Yes. The spreading of particles by random movement is called diffusion.

Gertrude: Oh! Does diffusion happen only in gases?

Mrs. Thomson: No. diffusion happens in solids and liquids too. I am planning to show your class how it happens in solids and liquids in our next laboratory lesson.

Gertrude: That is great!

Mrs. Thomson: One thing to remember is that, even though diffusion takes place in all three states of matter, it takes place faster in gases than in liquids and solids.

Gertrude: It must be because particles in gas move around faster than those in solids and liquids, right?

Mrs. Thomson: Yes. Similarly, diffusion takes place faster in liquids compared to solids.

Gertrude: And that shows that particles in a liquid move around faster than those in solids.

Mrs. Thomson: Yes, Gertrude. You got it. Now I have to leave you. It is time for my next lesson.

Gertrude: Thanks a lot, Mrs. Thomson.

Mrs. Thomson: You are always welcome!