Lesson video

Hello everybody.

My name's Ms. Couves, what's your name? Nice to meet you.

I'm so excited to be teaching you today.

Today I'm going to be teaching you some science.

Science is my absolute favourite subject, and we're going to be learning chemistry, which is my favourite part of science.

Before we get started, I thought I would tell you about what I've been doing during the lockdown.

During the lockdown, I've been growing plants in my garden, this is one of my chilli plants.

Can you see how the chilies are turning from yellow at the top to red at the bottom.

When they are all red, they will be ready for me to eat.

Can you see this one is almost ready.

I'm so excited to taste them.

What have you been doing during the lockdown? That sounds exciting too.

Today we're going to learn about what makes something pure.

It's a really important part of science.

And we're going to start by looking at what makes something a solid, a liquid, and a gas, and imagining what the particles that make up those compounds look like.

So, if we're ready, let's get started.

We're going to start by thinking about solid, liquids, and gases, and what they look like.

We're then going to talk about the how the particles behave.

And then we're going to talk about what makes something pure or impure.

Everything is made up of particles and those particles behave in different ways depending whether something is a solid, a liquid, or a gas.

In this lesson, you are going to need three things, an exercise book or paper, a pencil, and a glass of water.

If you don't have one of these things, pause the video now and go and get them.

First we're going to look about solids, liquids, and gases.

We're going to start by looking at water.

When we normally think of water, we think of water in a cup, is water in a cup a solid, a liquid, or a gas? Water that we get from the tap and put into our cups, is liquid water, but actually water can come in a solid form, a liquid form and a gas form.

When water is a solid, we call it ice.

What do we call solid water? Ice.

When water is in the gas form we call it steam.

What do we call gaseous water? Steam.

All three of these substances are made of the same type of particle called the water particle.

So all of these substances are all water.

Everything is made of particles.

Particles are tiny, tiny, tiny, tiny bits of matter that we can't see.

And different substances have a different type of particle.

The particle in water, ice, and steam is the water particle.

So, if the particle is the same, why don't all of these substances look so different? Well, it's because the particles are arranged in different ways.

Which particle is used to make ice, water, and steam? The water particle is used to make ice, water, and steam.

What's the difference between ice, water, and steam? The arrangements of the particles are different in ice, water, and steam.

Let me show you how the particles are arranged in ice, water, and steam.

So, I'm going to show you what the particles look like in ice, water, and steam.

In ice, the water particles are arranged in ordered rows.

I draw my particle as a circle, and I know that my particles in ice are touching and in ordered rows.

So I'm going to draw all of the particles, the same size in a nice ordered row.

Why do you think I'm making sure that my particles of ice are the same size? My particles are ice, of ice are the same size because they're the same type of particles.

So all of my particles should be exactly the same.

What were the two important things about my particles in ice? The particles in ice are touching and they're in ordered rows.

Actually, it's not just ice that has particles arranged like this, all solids have particles that are arranged so that the particles are touching and in ordered rows.

What do the particles in a solid look like? Particles in a solid are touching and arranged in ordered rows.

Let's think about water.

Water is a liquid.

The particles in a liquid are still touching, but they're not in ordered rows, they have a random arrangement.

Again, I'm going to tool my particles as circles.

They're going to be the same colour and size because they're the same particles as in ice.

But this time they're touching, but not in an ordered rows.

What's important about the particles in water, liquid water? They are touching, and they have a random arrangement.

This is what particles look like in a liquid.

What do the particles look like in a liquid? Particles in a liquid are touching, and have a random arrangement.

Pause the video and draw yourself the particles in a solid and the particles in a liquid.

Press play when you're ready to continue.

Finally, we're going to look at the particles in a gas.

Steam is a gas.

Particles in a gas are not touching.

We're still drawing up articles within the same colour and the same size, because they're still the same particle.

What particle makes ice, water, and steam? The water particle.

So all of these circles represent the water particle.

What is the difference between ice, water, and steam? The difference between ice, water, and steam is that the way the particles are arranged.

In steam the particles are not touching.

And they're also moving very fast.

We show that the particles in steam are moving very fast by drawing these lines to represent the movement of particles.

What do the particles in gases look like? The particles in gases are not touching and they're moving very fast.

Pause the video and make sure you have a diagram to represent solids, a diagram to represent liquids, and a diagram to represent gases.

Check your diagrams look like mine.

How do we know that the same particle is used to make ice, water, and steam? We know that the same particle is used to make ice, water, and steam because the particles look the same.

They have the same colour and the same size.

Remember that we are representing the particles in ice, water, and steam using these diagrams, this is not what they actually look like.

So, let's think about a new substance, wood.

Wood is made from wood particles.

What particles is wood made from? Wood particles.

Is wood a solid, a liquid, or a gas? Wood is a solid.

So we're going to be thinking of drawing the particles in a solid.

In a solid, should the particles touch? Should the particles be ordered? And should they be moving fast? Now you've answered those three questions, have a go at drawing the particles in wood.

Press play when you're ready to continue.

Wood is a solid.

The particles in a solid are touching and in ordered rows, but not moving very fast.

In fact, particles in a solid, just vibrate on the spot very, very slightly.

Tick your answer if you've got it correct and correct it if you need to.

Let's think about another material.

What do the particles in oil look like? Is oil a solid, a liquid, or a gas? Should the particles be touching? Should the particles be ordered? Should the particles be moving fast? Pause the video and have a go at drawing the particles in oil.

The particles in oil are arranged so that they are touching, but in a random arrangement because oil is a liquid.

What about the particles in helium? Helium is inside a helium balloon.

Is helium a solid, a liquid, or a gas? Should the particles touch? Should the particles be ordered? Should the particles be moving fast? Pause the video and draw the particles in helium.

Press play when you're ready to continue.

Helium is a gas.

The particles in a gas are not touching and moving very fast.

Tick your answer if you've got it correct, or fix it if you need to.

Now we know how the particles are arranged.

We're going to have a think about the how particles behave? Is ice a solid, a liquid, or a gas? Ice is a solid.

Solid particles vibrate on the spot, vibrates on the spot.

This is a solid particle.

They vibrate on the spot.

Show me what a solid particle does.

Yes, they vibrate on the spot.

Liquid particles can slide past each other.

Liquid particles can slide past each other.

Show me what liquid particles can do.

That's right.

They can slide past each other.

Gas particles move very fast in all directions.

Gas particles move very fast in all directions.

Show me what gas particles do.

Good.

They move very fast in all directions.

Let's add to our diagram, the movement of particles.

How does solid particles move? Solid particles vibrate on the spot.

How do liquid particles move? Liquid particles can slide past each other.

What about gas particles? How do gas particles move? They move really fast in all directions.

Pause the video and make sure you have those notes in your diagram.

Press play when you're ready to continue.

In which states of matter are particles moving fast in all directions? Point to the screen.

Gases are moving fast in all directions.

Point to the state of matter in which particles are touching.

Particles are touching in solids and liquids.

Point to the states of matter where particles are arranged in ordered rows.

Particles are arranged in ordered rows in solids.

How do the particles in oil behave? Option 1, they are touching and vibrating on the spot.

Option 2, they are touching, but can slide past each other.

Option 3, they are not touching and move very quickly in all directions, or option 4, they are touching but not moving at all.

Option 2, they are touching but they can slide past each other because oil is a liquid.

How did the particles in wood behave? Option 1, 2, 3, or 4.

Option 1, particles in solid like wood are touching and vibrating on the spot.

Show me the particles in solids, that's it, vibrating on the spot.

How did the particles in helium behave? Option 1, 2, 3, or 4? Option 1, 2, 3, or 4? Option 3.

They are touching, they are not touching and move very quickly in all directions because helium is a gas.

Now we're going to think about pure substances and impure substances.

What is the difference between pure and impure substances? Helium is a pure substance.

That means it contains any one type of particles, the helium particle.

How many types of particles are there in a pure substance? There is one type of particle in a pure substance.

An impure substance contains more than one type of particle.

Air is an impure substance because it contains more than one type of particle.

I'm going to show you what this looks like using our particle diagrams. I am going to use different colours to represent the different types of particles.

Have a look at the diagram.

How does the diagram of air show us that there are two different types of particles? The diagram shows us there's two types of particles, because there are two different coloured particles.

How does the diagram of helium show us that helium is pure? The diagram shows us that helium is pure because it contains only one type of particle.

Pause the video and write down the definition of a pure substance.

You might want to use a diagram to support your answer.

What? Pause the video and write down the definition of an impure substance.

You might want to use a diagram to support your answer.

Let's check those definitions.

A pure substance contains only one type of particle.

And an impure substance contains more than one type of particle.

Pause the video and have a go at drawing a pure solid and an impure solid.

Press play when you're ready to continue.

In a solid, particles are arranged in ordered rows, but in a pure solid there's only one type of particle, and in an impure solid there's more than one type of particle.

Tick or fix your answer.

How does my diagram of an impure solid tells me, tell me that there's two different types of particles? My diagram of an impure solid shows me there's two types of particles because there's two different colour circles.

Tap water isn't actually pure water.

It contains other substances too.

We're going to put, going to do a practical to prove this.

If you don't have the equipment for this practical, you can just follow along with me.

You need to place your cup of water somewhere warm and wait for the water to evaporate.

This might take several days.

Pause the video and go ask your parent where you can leave your cup of water to evaporate.

Press play when you're ready to continue.

I started this experiment a week ago and I have my cup here so that we can look at the results.

Have a look at my cup.

Can you see the marks on the outside? There are some particles from my tap water that are not water particles.

Can you see? These are called salt particles.

In my tap water there were water particles and salt particles.

When the water particles evaporated, the salt particles were left on the outside.

If my tap water contains water particles and salt particles, is it pure or impure? My tap water contains water particles and salt particles, so it is impure.

Good luck with your experiment.

I hope you get to see the salt particles.

Remember to complete the quiz, and I'll see you in our next lesson.