Teaching Students About Solids, Liquids, and Gases

All about Solids, Liquids, and Gases for Kids

Everything in the world can exist: solid, liquid, or gas. These are the three states of matter.

What is the matter?

The matter is everything you can see, feel, or touch around you. It includes things like the air we breathe and the items we use in everyday life.

Everything that exists as a form of matter can be weighed to determine how much matter is in them. That’s their mass! We can also measure how much space they take up in the form of their volume.

Keep reading to find out the basics of solids, liquids, and gases!

What are solids?

Solids are all around you and around us right now. If you point to anything in the room, chances are it would be classed as a solid! These might be:

  • The wooden chair you’re sitting in
  • A pencil that you’re using to write
  • The apple in your packed lunch

Solids can have a whole range of different physical characteristics. For example, they can be soft like fur or silk or complex like a rock!

There’s no limit to their size, either. Consider that the smallest grain of sand or rice is a solid, but so is a massive asteroid hurtling through space.

So what do all these different things have in common? First, they all hold their shape because the invisible molecules they’re made up of are tightly packed together.

Features of a Solid

  • A solid can be weighed to determine how heavy it is.
  • As a form of matter, solids occupy space. That is to say; they exist in the world.
  • Solids have a fixed shape and volume, meaning they don’t move to fill a container when placed in it. Instead, they hold their shape and volume.
  • Solids cannot be compressed into a smaller space very efficiently because there’s not much space between the atoms.

Examples of Solids

As mentioned before, there are too many examples of tangible things at room temperature to count. Here are just five of them:

  • Bricks – When building a house, the walls have to hold their shape, meaning they have to be solid all the time. Bricks have been used for thousands of years to create stable structures.
  • Coins – Coins are an excellent example of an everyday solid that we don’t even consider. Most metals can be melted down at extremely high temperatures to turn them into a liquid for a short time, then reformed into something else, but you have to go out of your way to do this. So they’re solid most of the time.
  • Sand – You might not think of sand as a solid because putting a lot of sand in a container spreads out to fill the shape; this would suggest that it’s a liquid. But what’s happening is that each grain of sand is a tiny solid.
  • Chocolate – Think about your favorite bar of delicious, sugary chocolate. Unless you’ve been sitting in a roasting hot car, chocolate is firm and holds its shape when you take it out of the wrapper, so it’s solid. But it doesn’t stay that way when it melts!
  • Ice – This isn’t solid at room temperature, unlike the other examples. Water turns into a solid when it’s below freezing. Remember this one for later!

What are liquids?

Liquids are another form of matter. For example, before a solid turns into a gas by changing states, it will become a liquid at some point in the process.

Liquids are tiny particles packed close together but not as tightly as solids. These molecules are not arranged in any specific pattern, so they can move around and slide past each other. That’s how a liquid changes its shape.

Features of a Liquid

  • A liquid can be weighed to determine how heavy it is.
  • As a form of matter, liquids also occupy space like solids.
  • Liquids do not have a fixed shape but a fixed volume; this means they spread out to fill a container when
  • Liquids cannot be compressed easily into a smaller space because there isn’t much space between the atoms.

Examples of Liquids

  • Water – This is the first thing many think of when they’re asked to name a liquid. Water is found worldwide in our oceans and is a liquid at room temperature. But remember that it’s also seen as a solid– whether it’s as snow on Christmas Day or permanent ice at the North Pole. So can it be gas too?
  • Blood – Our bodies are made of plenty of solids, but blood is one of the main liquids inside us! Measured in volume, the average human has around 5 liters of blood (or 10.5 pints) inside us.
  • Honey – Sweet and syrupy; honey comes from bees and is found as a liquid inside their hives. It might take forever to pour out, but it spreads out to fill a container and is a liquid!

What are gases?

Gases are one of the three states of matter. Like solids and liquids, they are everywhere. Common gases include oxygen and carbon dioxide – you can’t see them because they’re colorless, but they are in the air we breathe.

They’re made up of tiny molecules which are spread out. These molecules have so much energy that they constantly move around in different directions.

Features of a Gas

  • Even though they’re often invisible to the naked eye, gases are still a form of matter, which means they occupy space and can be weighed.
  • Gases do not have a fixed shape or volume; they fill a container they’re placed in, no matter their size or shape.
  • Gases can be squeezed and compressed into space because there’s a lot of space between the molecules.

Examples of Gas

  • Air – This air we breathe is made up of a few gases, including oxygen, nitrogen, neon, hydrogen, and carbon dioxide. It spreads to fill a container in every room and all over the planet!
  • Helium – The stuff that you pump into a floating balloon is called helium, and it’s incredibly lightweight. Making helium, a liquid, would have to be at a shallow temperature.
  • Water Vapour – Have you ever boiled water in a kettle? Boiling water gives off steam, which is a gaseous form of water known as water vapor. That’s all three states of matter relating to water!

Changing Between a Solid, a Liquid, and a Gas

As we’ve seen, some things can transform from a solid to a liquid and then to a gas right before our eyes; this is most often done by heating it, cooling it down, or through pressure.

Metals like iron have melting points that can be achieved in a furnace, but it would need far more than that to become a gas.

It happens in reverse, too. A gas can cool down, reducing the amount of energy in its active molecules. As a result, they might begin to join together and become a liquid, then eventually, a solid! However, the temperatures required to turn most gases into a liquid and then a solid are extreme.

There are a few solids that jump directly to gas. One example is dry ice, which is solid carbon dioxide. It turns instantly into its gas form.

An Example of Changing States: Water

We don’t need to look that far for an example of something that goes through all three states of matter.

Take water, for example.

At room temperature, water is a liquid.

By lowering the temperature to 0 °C or below, that water will freeze and turn into a solid.

When the temperature rises above 0 °C again, it will return to liquid form.

Now, if you heat water to its boiling point of 100 °C, it will turn into a gas vapor!

As that water vapor cools, it will condense on a surface and become liquid water again.

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