Lesson video

Welcome to today's lesson on molecular elements.

It's part of the unit atoms, elements, and compounds.

My name's Mrs. Mytum-Smithson.

I'm really pleased that you've come along to learn with me today.

I know that some of these keywords can seem a little bit daunting, but don't worry because by the end of the lesson, you'll become much more familiar with them, and you should be able to use them in full sentences with confidence.

By the end of today's lesson, you should be able to describe a molecule and draw pictures of elements made from molecules.

Today's keywords are molecule, monatomic, diatomic.

If you wish to read these keywords in a sentence, then there's some on the next slide.

So just pause it and have a read and then press play when you're ready to start the lesson.

Today's lesson has got two learning cycles.

Firstly, we're going to learn about molecules and non-metals.

Then we're going to move on to how to represent those molecules.

So the second learning cycle is representing molecules.

So the first learning cycle molecules and non-metals, let's get learning.

Here's the periodic table.

On the left-hand side, where all the elements have just been left white, they're either metals or metalloids.

And on the right-hand side, I've highlighted in pale green all of the non-metals.

Now, most of the non-metals are in the gas state at room temperature.

Here are the ones that are in the gas state at room temperature.

As you can see, there's quite a lot of them.

A few of them, however, are solid at room temperature.

So these are the non-metals that are solid at room temperature.

And you can see that bromine is in the liquid state at room temperature.

In fact, there's only two elements that are in the liquid state at room temperature.

One of them is bromine, and the other one is mercury.

Most of the elements on the periodic table are in a gas state or a solid state at room temperature, and there's only two, so that's mercury and bromine.

That's a liquid at room temperature.

So here's a quick check for understanding.

At room temperature, most non-metals are in which state? Are they in the solid state, the liquid state, or the gas state? Pause the video now for some thinking time, press play when you've got your answer.

Well done if you said gas state, absolutely correct.

Most of the non-metals are in the gas state at room temperature.

Some elements are monatomic.

That means that it consists of only single atoms. However, other elements are diatomic, consisting of two atoms of the same type chemically bonded together.

Let's look at the roots of these words.

So monatomic, mon meaning one.

So you might come across that as monochrome, meaning one colour.

So monatomic is one atom, and then we've got diatomic, that means two atoms. So the two atoms must be the same type and they must be chemically bonded or chemically joined together.

And we show that by them having an overlap.

Here's a quick check for understanding.

True or false? An element is always a single atom on its own.

Pause the video for some thinking time.

Press play when you've got your answer.

Well done if you said that that was false, and I want you to now justify your answer, so you've got two choices here.

A, some elements are diatomic, or B, all elements are diatomic.

Pause the video now, have a little think, and then press play when you've got your justification.

Well done if you said some elements are diatomic, not all elements, because remember we said that some elements were monatomic.

When you get two or more atoms join together, they're called a molecule.

Usually, this happens with non-metals.

Some non-metals are monatomic and do not form molecules.

So two or more atoms, diatomic, joined together are called a molecule.

So some of them don't form molecules.

For example, the noble gases.

Now the noble gases are listed in the very right-hand column of the periodic table, and they're all monatomic atoms. So here we go.

We've got helium, neon, argon, krypton, xenon, and radon.

They're all monatomic.

Some of the non-metals form diatomic molecules that contain two atoms, for example, O2, N2, H2, Cl2.

Let's have a look where they are on the periodic table.

You can see that they're in the shaded green bit, which means that they're non-metals.

And that subscript 2, so that little number 2 that sits below the line shows that there are two atoms of that element joined together.

So N2 would be two atoms of nitrogen joined together to make a diatomic molecule.

A quick check for understanding now.

Which symbol represents a diatomic element? Is it kr, Ne, Cl2? Pause video now for some thinking time and press play when you've got your answer.

Well done if you said Cl2.

Indeed that little number 2, that subscript number 2 next to the Cl shows that there are two CL atoms chemically joined together, meaning that is a diatomic molecule and that is a diatomic element.

Well done if you got that one right.

Let's check now to see how much you're learning.

How many atoms are in a diatomic molecule? Is it only one, only two, one or two, two or more? Pause the video now for some thinking time and press play when you've got your answer.

Well done if you said only two.

That's two atoms chemically joined together, so that is diatomic, di meaning two.

We went through that at the start.

Hopefully, you're getting the idea of this now.

Well done if you got that one right.

So some students have been talking about the noble gases.

We've got Lucas, Sofia, and Laura.

Which student or students are talking about the noble gases.

Lucas says, "They are diatomic molecules." Laura said, "They're listed in the right-hand column of the periodic table." Sofia said, "They only exist as monatomic atoms." Pause the video now, have a think about who you agree with and then press play when you've got your answer or answers.

Well done if you spotted that there were two students, Sofia and Laura, that were talking about the noble gases.

So they only exist as monatomic atoms, so one atom and they're listed in the very far right-hand side of the periodic table in that right-hand column.

Well done if you managed to spot those two students talking about the noble gases.

Here's task A, I'd like you to complete the missing words using only these four.

So you've got a choice of monatomic, diatomic, molecules, atoms, and you can use these words multiple times to complete the following sentences.

Some non-metals form something molecules that contain two something, e.

g.

, oxygen O2.

Some non-metals are something atoms and do not form something.

Noble gases are listed in the right-hand column of the periodic table.

They are something something.

Nitrogen, N2, is a non-metal that forms something something.

So pause the video, complete the missing words, and then press play when you've got your answer.

Well done for completing that task.

I know that sometimes it's hard to choose which word fits where.

So well done for completing that.

So let's get through them now.

Some non-metals form diatomic molecules that contain two atoms. For example, O2.

Remember, diatomic, two atoms. Some non-metals are monatomic atoms, and they do not form molecules.

Remember, a molecule is two or more atoms join together.

Noble gases are listed in the right-hand column of the periodic table.

They are monatomic atoms. Remember, monatomic meaning one atom.

Nitrogen, N2, is a non-metal that forms diatomic molecules.

Remember di, two, two atoms and then a molecule is two or more atoms joined together.

So well done if you've got that one right.

You've worked really hard during this first learning cycle about molecules and non-metals.

Now we're going to be moving on to representing molecules.

Molecules can be represented in a number of different ways.

So let's have a look.

The first way, we could either draw or we could have a 3D model of them.

We could have a 2D version of them, so this is just flat shaded circles.

Or if we were being really quick, we might just draw an outline.

If you notice, there's always an overlap or a join.

So we've got the overlap in the 3D, the 2D, and the outline there.

They're joined together.

We might also put the symbols for the element just to make it easier to know that which molecules we're actually talking about.

So here, which element are we talking about? I think you all know that H stands for hydrogen.

So here we're talking about hydrogen molecules.

So this would be H2.

We can also represent monatomic and diatomic substances in their states of matter.

So here we've got a monatomic gas.

So this is one of the noble gases.

This is helium.

monatomic, so there's just one atom there.

We've chosen to do 3D, and this is a gas 'cause you've got gaps between them.

And then we've got a diatomic gas, for example, oxygen.

So here you can see we've got two oxygen atoms joined together, meaning that it's a diatomic gas.

Let's do a quick check for understanding.

Which image represents a diatomic molecule? Is it A, B, or C? Pause the video for some thinking time.

Press play when you've got your answer.

Well done if you said B.

Diatomic means two.

So that is indeed a diatomic molecule 'cause we've got two spheres representing the atoms joined together.

Well done if you got that one right.

Now, we're onto the tasks.

What I'd like you to do is sort the statements and images into two lists with the headings monatomic and diatomic.

So here's the first two statements, noble gases such as helium and argon, then we've got another one, gases such as hydrogen and oxygen.

Single atoms not joined together.

Two atoms joined together.

N2, Rn, molecule, atom.

Then we've got these two diagrams here.

What you are going to do is you're going to do two lists.

So your first list is gonna be monatomic.

You're gonna select all the statements and images that go along with that.

And then we're gonna have another list and that's gonna be diatomic, and you're gonna select the statements and diagrams that go along with that one.

So pause the video, complete the task, press play when you've got your answers.

Well done for working really hard and completing that task.

You've got your two lists now, monatomic and diatomic, and we're just going to go through the statements and see how well you've sorted them.

So monatomic, these are the noble gases such as helium and argon.

Remember, it's that right-hand column, they're all monatomic gases, the noble gases, and diatomic, these are gases such as hydrogen and oxygen.

We've got monatomic.

They are single atoms not joined together.

We've got diatomic, two atoms joined together.

Then we've got monatomic, we call those atoms. And we've got diatomic, we call those molecules 'cause they're two or more atoms joined together.

And that's the definition from molecule.

We've got Rn, which is radon, which is a monatomic gas, and we've got diatomic, which is N2, so that 2 represents that they are two nitrogen atoms joined together, meaning that it's diatomic.

And finally, we've got the two diagrams. So monatomic, you can see that they're single atoms, and we've got the diatomic, you can see that they're two atoms joined together, making molecules, and these are both in the gas state 'cause we've got gaps between them.

So well done if you manage to sort all those statements and diagrams. You're doing really well so far this lesson.

Task number two.

So now we've got a table, and it's got some information missing.

So we've got a column that says the name of the element, then we've got the symbol for the element and we've got monatomic or diatomic, atom or molecule, and then we've got a simple outline drawing with the symbol included in it.

So what I'd like you to do now is pause the video and complete all of the blank spaces in this table.

Then once you've done that, you can press play, and we'll go through the answers.

Well done for working really hard and completing this table of information.

We're going to go through these bit by bit now.

So the first one, that element is chlorine.

So if you use your periodic table to look that up, well done.

And that is a diatomic.

So diatomic, you've got the little number 2 next to the symbol.

So that must mean that they're two, which must make it a molecule.

And we've got the drawing there to show you that it is a diatomic molecule.

Next we've got neon.

So this must be monatomic.

And so the drawing with the symbol must look like this.

Remember, it's a capital letter for represented elements.

So capital N, lowercase e.

If you've written a capital N and an uppercase E, then you're going to get that incorrect.

So it must be a lowercase second letter.

Then we are moving on to nitrogen.

So nitrogen, the symbol for nitrogen is N2.

You must have that little number 2, and it must be smaller and lower than the N, so it must be smaller and lower.

Otherwise, you're not writing it correctly.

So this is a diatomic, and it means that it's a molecule.

And you can see there we've got the symbols there showing that we've got two atoms joined together and that means that it's a molecule.

And finally, the last one, we've got argon, which is a noble gas.

All noble gases are monatomic.

If you look, there's no number two or three or anything next to the Ar.

So that is monatomic and that is an atom.

So we would just draw a single circle with Ar in it.

So well done if you've managed to get all of that correct, you've done really, really well.

So here's today's summary.

Many non-metals are in the gas state at room temperature.

Some non-metals form diatomic molecules that contain two atoms. For example, O2 is oxygen, N2 is nitrogen, H2 is hydrogen, Cl2 is chlorine.

Some non-metals are monatomic and do not form molecules.

Noble gases are monatomic and are listed in the right-hand column of the periodic table.

Well done for working really hard this lesson.

I think there were some difficult keywords and I hope by now that you are feeling very confident about using the words monatomic, diatomic, atom, and molecule.

You've done really well.

I hope to see you again sometime soon.