Lesson video

Hello and welcome to this lesson about group 0, the noble gases, from the unit Patterns in the Periodic Table.

My name is Mr. Gundry, and we're gonna go through this lesson together today.

I really hope you're looking forward to it because I am too.

The noble gases are very interesting elements.

So by the end of this lesson, you should be able to describe the properties of the noble gases, their uses, and explain why they are unreactive.

Now, in comparison to other groups of the periodic table, so group one elements and group seven elements, the group 0 elements are very unreactive, and we're gonna go through why in this lesson.

So there are two key words, two key phrases that we're going to use at various points in this lesson.

They are inert and obviously noble gas, which is the main theme of the lesson.

And on the next slide, there are some definitions.

If you would like to read through them, go ahead.

But we're just gonna go through them as we go through the lesson.

So this lesson is split into two parts.

The first part, we're gonna talk about the noble gases, kind of where we can find them on the periodic table, a little bit about them.

But we're gonna leave most of the bulk of their properties and what we use them for in the second 1/2 of the lesson.

So let's get started.

So the group 0 elements are found on the right hand side of the periodic table.

So we can see here highlighted on the periodic table on the screen, this far right hand column are known as the noble gases.

The elements that are included in group 0 include helium, neon, argon, krypton, xenon or xenon, radon and, more recently, oganesson.

So using your periodic table if necessary, which symbols represent elements from group 0? I'll give you a bit of time to have a think and read through.

And so pause as you do that, and press play when you are ready to continue.

Well, the answer is A and C.

B is a metal, it's not found in group 0.

True or false, the elements in group 0 are helium, nitrogen, argon, krypton, xenon, radium and oganesson.

True or false? Well, the answer is false and the reason why it is false, well, there are two options here.

Why don't you have a read through them, pause as you do so, and press play when you're ready to move on.

Well, the answer is B.

Group 0 elements do not include nitrogen and radium.

So helium, argon, krypton, xenon and oganesson, they are group 0 elements.

Okay, so group 0 elements, as the clue is in the name, the noble gases, they are gases at room temperature.

Oganesson's the exception.

We're not really gonna talk about oganesson too much to be honest.

We're not gonna really talk about the elements too far down the periodic table.

Our trends tend to break down a little bit.

The further down we go, the heavier the elements get.

So we're gonna focus really on helium, neon, argon and krypton and xenon.

They're gonna be the main ones we focus on in this lesson.

Until we do though, we're gonna quickly go through some facts about oganesson, just so that you can see some interesting properties that don't really occur in the rest of the group 0 elements.

So oganesson is very highly radioactive, and that's because it's really, really heavy.

Its atoms are really heavy, and so they radioactively decay.

We're not gonna go through that in today's lesson, but maybe something for another time.

Only a few atoms of oganesson have ever been synthesised.

And because of that, we don't really know much about its chemical properties.

We can only make predictions about the ways that we think that oganesson would behave.

We think it would be a solid at room temperature.

Now, that goes against the trend as we know all of the elements in group 0 are gases.

Obviously with this prediction, oganesson would not be.

Its physical properties, such as boiling point and density, have been predicted.

But again, because there's so few of the atoms that have been synthesised, we just don't know.

Okay, moving on then.

So all of the group 0 elements have a full outer shell of electrons.

If you remember the shape of an atom, the structure of an atom, we have protons and neutrons in the nucleus, and then electrons orbiting around the outside.

And the number of electrons in the outer shell dictates the chemical properties of that element.

Well, group 0 elements have a full outer shell of electrons.

So they're very stable.

We say they're very stable.

Now, what that means is because they are very stable, because they have this full shell of electrons, then they are unreactive.

There is no kind of electrons that need to be gained.

There are no electrons that need to be lost in order to reach a full outer shell.

And so they are very stable elements.

Helium in the first period of the periodic table, that first shell can only be filled up to two electrons.

And then neon in the next shell, the second shell of the periodic table or the second period of the periodic table, it can be filled up to eight electrons on the outermost shell.

But you can still see that those two electrons on the inner shell, which would be helium's full outer shell.

So all atoms of each element in group 0 have a full outer shell of eight electrons.

True or false? Well, the answer to that is false.

I'd like you to read through these two justifications, pause the video as you do that, and then press play when you're ready to see the answer.

Well, the answer is A, helium only has two electrons in its outer shell.

This is still classed as a full shell, but it's obviously not as many as neon has in its outer shell.

Some students are discussing then the noble gases.

So we've got a task here for you.

I'd like you to read through the four students, so Andeep, Lucas, Sofia and Laura's statements.

I'd like you to identify who is correct, and I'd like you to update any incorrect statements.

So there might be one or two words that need to be changed, or perhaps maybe the whole sentence is wrong and needs to be rewritten.

I'm gonna give you a bit of time to do that.

So pause the video now.

And then when you're ready to go through the answer, press play.

Okay, so Andeep and Lucas are correct.

Group 0 is the far right column of the periodic table, and all of the elements have full outer shells, which makes them stable.

Lucas is also correct that helium has two electrons in its first shell and neon has eight electrons in its second shell, which is its outer shell.

And then Sofia and Laura are not correct.

So Sofia says group 0 elements are in the first column and are unstable due to incomplete outer shells.

Now, we know from Andeep and Lucas being correct that the group 0 elements are in the far right column, so they're furthest to the right, and they are stable because they have complete outer shells.

And Laura says helium has two electrons, making it stable just like argon.

It's not that it has two electrons that makes it stable, it's that those two electrons are in its outer shell, and that makes the outer shell complete.

So we've got here our statement for Sofia rewritten and our statement for Sofia rewritten.

So that is the first 1/2 of this lesson complete.

And now we're gonna talk about the properties and uses.

So well done on that previous section.

And we're gonna put a little bit more emphasis now on the ways that the elements in group 0 behave.

We've already talked about how the elements in group 0 have full outer shells of electrons.

Now, that means that they are unreactive, there's no need for them to react because there's no electrons that are going to be lost or gained from their outer shells.

And so that means that the atoms go around as singular atoms. They don't need to bond with anything to form compounds.

All molecules.

And so we describe them as monoatomic substances.

So at room temperature and pressure, they are monoatomic substances.

They also are colourless, so they don't have any colour.

So one of the gases that is in the atmosphere that you're breathing in right now, a very low percentage, but it's in the top couple of gases, is argon.

It's a monoatomic noble gas, it's colourless and it's unreactive.

The atoms, as we've said, don't need to bond because they have that full outer shell of electrons.

We can see a trend in their physical properties.

So as we move down the group, starting at the top with helium, working our way down to neon, argon, krypton, xenon, et cetera, we've got our boiling points increasing.

So we can see the boiling points increase, and that's represented in this bar chart on the screen.

So we can see that helium has a boiling point of about minus 260 so degrees, and we can work our way up to neon, slightly warmer, argon, we're looking at minus 180 degrees perhaps, maybe 190, and further on as we go up or go down the group, should I say.

Which group 0 element then has boiling points lower than krypton? So a value lower than krypton.

So remember all of these are gases at room temperature.

So which one of these has a boiling point that is lower than krypton? So krypton being quite low in the periodic table for group 0.

So which of these elements have boiling points lower than krypton? Well, the answers are helium, argon and neon.

Because remember, as we go down the group, the trend is that the boiling points increase.

So we want a boiling point that is lower than it is for krypton.

Radon is actually lower in the periodic table, so would have a higher boiling point.

So the increase in boiling point is due to the fact that the atoms are increasing in size.

And as the atoms get bigger, they attract the other atoms around them much more greatly.

So the elements that are higher up on the periodic table, they have much smaller atoms, and so they don't attract other atoms as strongly.

As there is a stronger force of attraction, more energy will be needed to overcome those forces.

And so we get a higher melting and boiling point because more energy is required.

Okay, then, true or false, molecules of group 0 elements have weak forces between the atoms. Well, the answer to that is false.

And I'm gonna give you two statements here.

I'd like you to read through them both, pause as you do so, and then when you're ready to see which one is correct, press play.

Well, the answer is A.

The previous statement is false because we've said molecules of the group 0 elements.

The group 0 elements, remember, are monoatomic, they go around as singular atoms, and there are weak forces between those atoms. So there's also a trend in density.

If we remember, density is a measure of how much mass there is of a substance per unit volume.

So as the group 0 elements are gases, their particles are spaced quite far apart, and so generally have quite low densities.

But as we increase the mass of those elements, so as we go down the group, we actually see the density of those elements increase.

Helium is one of the least dense materials that we know.

And so we use it in things like these balloons, okay? If you've ever had an inflatable balloon, and not inflated through air from our lungs because that's the same density as the air around us.

Helium is actually less dense than the air around us, which is why the balloons float.

So going down the group, the mass of group 0 elements, atoms, decreases, shows no pattern or increases.

So as we go down the group, the mass of group 0 elements, atoms, decreases, shows no pattern or increases.

Well, the answer is C.

We're adding more protons and neutrons and electrons to the atom as we go down the group.

So the mass will increase.

So what that means then for the density then, as we can see here on this graph, as we go from helium down to radon, we have got an increase in density.

A balloon is filled with neon.

So neon has a density of about 0.

9 grammes per decimeter cubed.

So that's about one gramme per litre.

If air has a density of 1.

2 grammes per decimeter cubes, so slightly more than one gramme per litre, what would happen to the balloon? Is it going to float upwards? Is it going to sink downwards? Or is it gonna remain at the same level that it is left at? I'm gonna give you some time to think about that.

So pause now as you do so, and then press play when you're ready for the answer.

Well, the answer is A, and that's because neon has a lower density than air.

So substances that have a lower density are pushed upwards by the substances that have a higher density.

So one of the most important properties of the group 0 elements is that because they are inert, because they are unreactive, that means that they do not react.

And so they are non-flammable, and we can use them in environments where we want to avoid substances being caught on fire.

So you may know that oxygen makes up about 20% of the atmosphere that's required for combustion for burning.

So we use argon in environments where we are heating things up to very high temperatures that would cause them to react with oxygen and start burning.

And so we flood that environment with argon, an unreactive gas, it's very high abundance in the Earth's atmosphere.

So it's not something that we have a short supply of.

And so it avoids any kind of burning or combustion, which we wouldn't want to take place, and we wouldn't want that to happen when we were welding.

So we use argon as a shield gas.

We also use argon and xenon in light bulbs.

I mean, very old filament light bulbs.

Most light bulbs don't use filaments anymore.

But what would happen is we would heat this very thin piece of metal because we are passing electricity through it, and the electricity would cause the thin filament to start to glow because of how warm it was.

And if we'd had oxygen in that environment, it would start to burn and it would last for a very short period of time.

And so by filling the glass bulb with either a argon or xenon environment, it meant that it wouldn't catch fire and we could reuse it over and over again.

When a lit match is placed in a jar of helium, it would cause an explosion.

Well, the answer to that statement is false.

And I'd like you to read through these two justifications, and pause as you do so, and press play when you're ready to see which one explains why that statement is false.

Well, the answer is B, it will just put the match out because helium is non-flammable.

Oxygen would be required for the flame to continue burning.

And for there to be an explosion, we would need an explosive gas.

Okay, so your final task for today's lesson then is to go away and research the following group 0 elements and complete this table.

So we've got information on their atomic symbols and atomic numbers, some key properties and their common uses.

Now, for those of you that don't have access to resources to research, there is an additional material that you can use as a comprehension exercise to read through and kind of pick out the key information required for this.

But I would recommend, if you do have access, to do some research, that you go away and you do that independently without the use of the additional material.

I'm gonna give you some time to do that.

So pause the video as you do.

And when you're ready to see some suggested answers for some of this, but also the actual answers for the rest, then press play.

Well, helium has the atomic symbol of capital H, lowercase e.

Neon is capital N, lowercase e.

Argon is capital A, lowercase r.

Krypton is capital K, lowercase r.

And xenon is capital X, lowercase e.

We can see that the atomic number increases as we go down the group.

But the key properties are that they are, as we know already, all gases.

Helium and neon are light gases.

They are less dense than air.

Argon is a similar density to air, whereas krypton and xenon are heavy gases.

They are more dense than air.

So if you fill balloons with those gases, they would actually sink.

All of them are colourless gases.

However, if we pass electricity through them, then we get different colours.

So helium is a yellow-whitish colour, neon is a reddish-orange colour and argon is a violet colour.

Krypton is a blue-white colour and xenon is a very similar kind of blue colour.

So some common uses.

Helium is used in balloons.

It's used in breathing mixtures, as well as cooling devices for super cooling, things like CERN, the Large Hadron Collider.

Neon, as we know, is used in neon signs, high voltage indicators.

Argon is used in light bulbs or welding as an inert shield gas.

Krypton is used in lighting and photographic flashes.

Again, probably less so in the modern era, but that's what traditionally it was used for.

And xenon is again used in flash lamps and ion propulsion systems. Now if you've done a bit of research, you will hopefully know where we see those, or if you've done the comprehension exercise as well.

Really well done on today's lesson.

I think you've done a great job.

I hope you've enjoyed learning about the group 0 elements as much as I have.

Just a bit of a summary, the noble gases are in group 0 of the periodic table.

And we know that they are unreactive.

At room temperature, they are all gases, obviously with the asterisk there, the exception of oganesson, but don't worry about that, we haven't done too much research into oganesson yet.

They have complete outer electron shells, which makes them stable.

And moving down the group 0 elements, we know that the density and the boiling points increase.

Thank you for learning with me today.

I hope to see you again soon, bye-bye.