The three phases of matter – Solids, liquids and gases

Solid melting (PHOTO: Getty Images/Gallo Images)
Solid melting (PHOTO: Getty Images/Gallo Images)

Everything around you – and even your body – is made up of the three phases of matter. Let’s find out more. 

The whole world and everything we can see around us is made up of matter. Matter can be ob-served because its mass can be weighed and it takes up space.“Material” is matter with a specific function.

For example, when we use a specific kind of matter to make an object such as a wooden or metal table, we say the material we used is wood or metal.

Some materials such as wood and metal are solids, others such as water and petrol are liquids, and others such as oxygen and steam are gases.

We call these the three phases of matter.Let’s take a closer look at these three phases of matter that occur everywhere around – and inside – us.

Teeny-tiny particles 

For a better understanding of the difference between solids, liquids and gases, we need to look at what they’re made of. Scientists discovered that all materials are made of teeny-tiny particles called atoms and molecules.

They’re so small you can’t see them with the naked eye – or even with a standard microscope. The characteristics of these particles will help you understand why the phases of matter – solids, liquids and gases – differ from one an-other.Firstly, it depends on how close together the particles are.

The closer they are, the stronger they attract one another. Secondly, we have to look at the way the particles move. If we heat the material, the particles move faster and with more energy.

Phase transition 

A material can change from one phase of matter to another. We call this phase transition or phase change.

For ex-ample, when water freezes and becomes ice,it’s undergone a phase transition from a liquid(water) to a solid (ice). If the sun heats a puddle of water so it evaporates, this is a transition from a liquid (water) to a gas (vapour).

You’ll notice these transitions are usually the result of a change in temperature but the pressure in the atmosphere can have the same effect.

Sublimation refers to the direct transition of a solid to a gas (without passing through a liquid phase). For example, in a dry climate ice(solid) can transition directly into vapour (gas).

The opposite can also happen – a gas transitions directly into a solid. An example of this is frost. Extreme, sudden cold can cause the vapour (liquid) in the air to freeze and turn into ice (solid). Then we call it de-sublimation.

Water vapour droplets on window (PHOTO: Getty Imag

The particles of solids

We know solids keep their shape –for example that table made of wood or metal. Solids stay the way they are. The reason why solids don’t change shape is because their particles are packed super close to one another.

The space between the particles in a solid is s in a solid vibrate in place but can’t move past their neighbouring particles – the attraction be-tween the particles is too great. The colder it gets, the tighter the particles pack together as the vibrations between them slow down.

Because the particles are so tightly packed, they attract the surrounding particles, forming a rigid (or solid) pattern. ) This is why a solid object keeps its shape and stays where you left it. If a solid is heated, the opposite happens.

The particles start vibrating faster and move If the temperature is high enough, the solid can transition to a liquid or even a gas.

The particles of liquids  

Liquids are more mobile. They flow and take on the shape of whatever containers they’re in. Milk fills the bottle or carton in which you buy it, but once you pour it into a glass, it takes on the shape of the glass, filling it from the bottom.

Although still fairly close together, the particles in a liquid are slightly further apart than in a solid. Because the particles in a liquid are further apart, the volume of a material is larger in its liquid form than in its solid form.

The particles in liquids don’t hold a fixed position like they do in solids. They can move around and mix with other particles – but they can’t move too far away from the other particles because there’s still an attraction between the particles that loosely holds them together.

This is why liquids can change shape to flow and adapt to the shape of the containers into which you pour them. But the space between the particles is still small enough so you can’t compress liquids a lot.

Can you think of a few liquids? We’ve already mentioned water, petrol and milk. What about fruit juice, paraffin and even blood? Yes, there are liquids all around and even inside our bodies. 

The particles of gases

In gases the particles are much further apart than in solids or liquids because the attraction between the particles is small. This makes gas even more mobile and fluid than liquids.

There’s a lot of space between the particles and they move around constantly. This is why we can compress gases to fit into a smaller container.

While gas particles move around, they clash with one another and with the sides of the container they’re in. They also take on the shape of the container in which you put the gas.

A gas stove’s gas fills the canister in which you buy it. The air you blow into a balloon fills the balloon completely. When the gas canister’s tap is opened or the balloon bursts, the gas escapes and its particles scatter in the atmosphere.

Solid melting (PHOTO: Getty Images/Gallo Images)
Solid melting (PHOTO: Getty Images/Gallo Images)
Milk is a liquid (PHOTO: Getty Images/Gallo Images
Milk is a liquid (PHOTO: Getty Images/Gallo Images)
 (PHOTO: Getty Images/Gallo Images)
(PHOTO: Getty Images/Gallo Images)