Lesson video

Hello, my name is Mrs Clarke, and today I'm going to be helping you learn about the properties of group zero elements.

This is part of the unit Groups of the Periodic Table.

We're gonna be looking at where group zero are on the periodic table, we're gonna be looking at some of the uses in our everyday world for group zero elements, and we're also going to be looking at the electronic structure.

Now it would be really helpful if you've got a periodic table to sort of refer to, so if you haven't got one go and get one, pause the video and join us when you're ready.

And so, the outcomes for today's lesson are that by the end of it we should feel much more confident about being able to describe some of the applications, or uses for group zero elements and explain how their properties are determined by their electronic structure.

So, let's get going.

Here are some of the key words for today, inert, and noble gas.

And here's the words written into a sentence.

You might want to pause the video and make some notes for yourself here about these two words.

So, this lesson has been divided into two.

We're going to first of all look at the electronic structure of group zero elements, and then later we'll move on to the properties and uses.

So, let's start with electronic structure.

So, here's a periodic table.

You should all be quite familiar with this by now.

If you look at the top you'll see the numbers, the group numbers.

At the far-right hand side here we've got group zero and the elements in group zero you can see there are helium, neon, argon, krypton, xenon, radon and oganesson.

Make sure that you can recognise the symbols there.

Let's just have a quick check.

Which of these symbols represents elements from groups in zero? Well done if you said neon, A, and well done if you said C, xenon.

If you said rhodium, B, that's a transition metal, so not group zero.

Here's another check.

So, here's a statement.

The elements in group zero are helium, nitrogen, argon, krypton, xenon, radon and oganesson.

Is that true or is that false? Hopefully, you know it's false.

Can you justify why you've said it's false? And you should notice that it's B.

Group zero elements do not include nitrogen and radium.

Nitrogen's in group five and radium's actually in group two.

Group zero elements are gases at room temperature.

Room temperature's around about 20 to 22 degrees centigrade usually.

So, they're normally all gases at room temperature and oganesson is an exception.

So, here's some facts about oganesson because you might not have come across that before.

It's highly radioactive.

Only a very few atoms have ever been made and so we don't know a lot about the chemical properties of oganesson.

We expect it to be a solid at room temperature and some of the physical properties like boiling point and density have been predicted.

Group zero elements are also called the noble gases as they're very unreactive or inert.

There's both of the key words for today's lesson there.

So, group zero elements, we call them noble gases because they're very unreactive and that's due to the number and arrangement of their electrons.

If you've got your periodic table beside you, I wonder if you could find helium on there.

And what you'll notice is helium has an atomic number of two, which means it's got two protons and so there will be two electrons.

How about neon? Find neon.

So, neon has 10 protons and 10 electrons.

So, let's think a little bit more about those.

So, all the group zero elements have a full outer shell of electrons and that makes them very stable as they don't need to lose, gain or share any electrons.

So, they're very stable and unreactive.

So, here's helium and helium has two electrons, remember, and those fill the first electron shell.

The first electron shell, if you remember, can hold up to two electrons.

Here's neon.

It has 10 electrons and so we fill the first shell with two electrons and then the second shell is also full with eight electrons.

So, two plus eight equals 10.

And the second shell can hold up to a maximum of eight electrons.

So, which of these atoms could actually be in group zero? Have a look at the structures carefully and make a decision which atom, or atoms could be group zero.

So, which have you said? So, if you said A, well done.

If you have a look at that, it has got a full outer shell.

Look at the outermost ring, the outermost shell, it's got eight electrons.

And we have a quick check, and all the electron shells are full.

B, it hasn't got a full outer shell, so that can't be in group zero.

And C looks like it should be in group zero, but unfortunately the first shell is not full.

So that diagram has been drawn incorrectly.

So, the answer is A.

So, let's have a quick check.

I'd like you to give me the protons and electrons for neon.

How many? And draw the electronic structure of neon using the circles to represent electron shells and crosses to represent electrons.

And then if you could do the same for argon as well.

Pause the video and rejoin us when you're ready.

So, neon looks like this on the periodic table, and so that means there's 10 protons and 10 electrons.

And then the electronic structure for neon would look like this.

There are two shells.

The first shell, the innermost one, can hold up to two electrons.

And then the second shell, which is the outer shell for neon, this can hold up to eight.

And this one is holding eight.

So, two plus eight is 10.

So quick check.

Argon.

If we look at argon, it will look like this on the periodic table.

So, there are 18 protons and 18 electrons.

And the electronic structure for argon looks like this.

There are three shells this time.

Two in the first shell, eight in the second shell, and eight in the third shell.

If you add all those up together, two plus eight plus eight, it adds up to 18.

So, let's have a look at task A.

Here we've got a table to complete.

We've got the group zero elements.

We've got the number of protons, number of electrons, and then their status of the outermost shell.

That's just to say whether it's full or not full.

So, pause the video and have a go at this and come back when you're ready.

Let's have a look at the answers.

So, argon, 18 protons, 18 electrons, and that would have a full outer shell, two, eight, eight.

Well done.

Radon, we know it's got 86 electrons, a full outer shell.

And so, if it's got 86 electrons, it will have 86 protons.

Okay.

The next line, a mystery element.

So, you might've wanted to use your periodic table here to have a look and see what element that might be.

And it was xenon.

So, if it's got 54 protons, it's got 54 electrons.

And because we know it's group zero, it will have a full outer shell.

Krypton, periodic table will tell you it has 36 protons, 36 electrons, and a full outer shell.

And the last mystery element at the bottom there has two electrons.

Therefore, it'll have two protons.

Atomic number two is helium, and that will be a full shell.

Well done if you've got all of those correct.

There's a lot to think about there.

Let's have a look at the properties and uses of group zero elements now.

Group zero elements exist as colourless monatomic gases at room temperature and pressure.

Let's just have a little think about that word monatomic.

So, mon or mono means single, so single atoms. So, group zero elements exist as single atoms at room temperature and pressure.

The atoms don't need to bond with other atoms to make molecules as they have this full outer shell of electrons, and that makes them very stable.

It also makes them chemically inert or unreactive, one of our keywords today.

So here is a bar chart about boiling point, and what's interesting is to learn about the trend here.

On the bar chart at the bottom on the x-axis we've got the elements helium, neon, argon, krypton, xenon, and radon.

And on the y-axis, we've got boiling points.

If you look at the top of the y-axis, that's zero degrees c.

And what you notice is that as we go down the group, so helium's at the top, radon's towards the bottom.

As we go down the group, boiling points increase.

That means they become closer to zero degrees C.

That's an interesting thing to remember, an interesting trend to remember.

So, let's have a quick check.

Which group zero elements have boiling points lower than krypton? You might like to use your periodic table here to look at where krypton is in group zero.

Well done if you said helium, and argon, and neon.

They all have boiling points which are lower than krypton.

Remember the trend, boiling point increases as you go down the group.

So, the increase in boiling point is due to this.

Atoms increase in size as we go down the group.

So, helium would be the smallest atom.

And because of that, the forces of attraction between these larger atoms are stronger.

And so more energy is needed to overcome these stronger forces towards the bottom of the group.

And here we've got a graphic to help you, and you can see the forces of attraction between them.

And here we've got two larger atoms, and the forces of attraction here are stronger between them.

So, quick check.

Molecules of the group zero elements have weak intermolecular forces.

Think about that one.

Is it true, or is it false? Well done if you thought it was false.

And can you justify your answer? What would be a good statement to say here? It is false because option A is correct.

Group zero elements are monatomic, and they have weak forces between their atoms. Group zero elements also show a trend in density.

And remember, density is the mass of a substance per unit volume.

And group zero elements are gases, so their particles are spaced out.

And so, they all have low density because there's the large volume there.

They're spaced apart, their particles.

And this is really useful in balloons, for example.

Helium is used a lot in balloons because it's less dense than air, and so it will float.

So, quick check.

Going down the group, the mass of group zero elements, atoms, do they decrease, show no pattern, or do they increase? So, the mass of group zero elements.

Hopefully, you've said they increase, because remember, they get larger, so the mass is going to increase.

Here we've got a chart showing density, and you can see that there's a clear trend there in terms of density.

It increases as we go down the group.

Remember, helium is at the top of the group, radon is towards the bottom.

Helium has a low density, and radon has a higher density.

So, we've got another trend there.

The density increases as we go down the group.

Density increases as the mass of the atoms increases.

So, a quick check.

A balloon is filled with neon.

Neon has a density of 0.

9 grammes per decimeter cubed.

If air has a density of 1.

2 grammes per decimeter cubed, what would happen to the balloon? Would it float upwards? Would it sink downwards? Or would it sort of stay in one place? What do you think? It would indeed float upwards, because neon has a density which is less than the density of air, so it would float.

Group zero elements have similar chemical properties.

They're all non-flammable, and that's really, really useful.

So, argon, for example, is used to provide an inert and reactive atmosphere when we're welding, and argon and xenon are used in light bulbs, which get very hot.

Here's a quick check.

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

Is that true, or is that false? It's false, because, can you justify your answer? Which one of those is the right justification? It's B, because helium, as with all group zero elements, is non-flammable.

Group zero elements cannot conduct electricity, as they don't have any free or delocalised electrons to carry charge.

But what they do do is glow when you pass a high voltage through them, and they don't decompose.

This is a really useful property in signs, for example.

Neon is used in a lot of signs that you'll see around the place.

Xenon is used in car headlights, and krypton is used in lasers.

So, three uses there.

So which tests could we use for a group zero gas? Which one of these would be useful to be able to test an unknown gas to see if it was group zero? Indeed, it's option C.

Option A is the test for hydrogen gas.

Option B is the test for carbon dioxide gas, and option D is the test for oxygen gas.

Other uses of group zero elements are double glazing.

Krypton is a good thermal insulator, and radon is actually highly radioactive, and is used in radiotherapy to treat cancer.

What key properties does krypton have which explain why it's useful in double glazing? So, have a look at all of these properties and which ones are particularly useful for double glazing.

It's useful to be colourless, because it's a window.

It's useful for it to be unreactive, and it's useful to be a good thermal insulator.

Well done if you got all three there.

Let's have a go at task B.

We've got a table of data here, and what we can do when we know some of the properties, and the trends in the group, we can actually use it to predict values for other members of the group.

So, we're gonna use the data to estimate the missing information.

Now, remember what we've just been learning about.

We've been learning about trends, about atomic mass, about the size of the atom, boiling point and density.

So, if you can remember those trends, it will be easier to do this task.

So, pause the video and rejoin us when you're ready.

So, let's look at the answers.

Remember these are estimates.

So, if we look at the periodic table, helium will have a relative atomic mass of four.

You can read that off the periodic table.

The next line down, we don't know what the element is, so we have to look to see if we can find the relative atomic mass on the periodic table, and if we do, we'll see it's neon.

And then the atomic radius, the PM there stands for picometer, which is a unit of measurement.

And that's 38.

So, you would estimate it would be between 31 and 71.

And then we've got to also look at density, and that would be higher than helium, but lower than argon.

So, we've got an estimate of 0.

85 to 1.

00 there.

Argon, so we're looking for boiling point here.

So, the boiling point of neon was minus 246 degrees centigrade, and krypton was minus 157.

So, it's going to be somewhere in the middle there.

So, there's an estimate for you.

Krypton, we can use our periodic table to find out the relative atomic mass, which is 83.

8.

And then the density, again, thinking about the trend, it will be more than 1.

78 for argon, but less than xenon.

So, there's an estimate in the middle there.

Xenon, we're looking for boiling point.

Remember the trend.

It will be higher than minus 157 degrees centigrade, and it will be lower than minus 62.

Remember the trend is that the boiling point is increasing and getting closer to zero as you go down the group.

So minus 100 to minus 115 there.

And then the last line is a mystery element.

So, if we look at the relative atomic mass on our periodic table, we know it's group zero, so that cuts down the number of elements we've got to search, and we will see it's radon.

So, well done if you've got all of that.

There's a lot of finding out to do and a lot of thinking about those trends.

Well done.

Let's do another question.

There's two questions here, 2a and 2b.

So, we're doing a matching exercise for the top one, and then looking at some examples of the use of glowing in 2b.

So, stop the video, have a go at those when you're ready.

So, here's the answers.

You might like to stop the video to check your answers here, because there's quite a lot of information on there.

But helium is less dense than air, and so it has good use in party balloons.

Trace the lines.

Krypton is a good thermal insulator, and so therefore it's useful in double glazing.

Radon is radioactive and used in radiotherapy, and I think I missed argon out, which is unreactive, so it's very good for welding.

And then 2b, so three examples for the use of the fact that group zero elements glow when a current is passed through them.

And we've got the shop signs for neon, we've got xenon in the car headlights, and we've got krypton with lasers.

Well done.

Here's our summary.

So, group zero elements are called the noble gases, or inert gases, because they're very unreactive with other elements.

Group zero elements have a full outer shell of electrons.

The atomic mass, density, and boiling points of group zero increase as we go down the group.

And group zero elements emit coloured light, they glow when a high voltage is applied to them, and they do not decompose.

So, remember we looked at neon being used for signs, xenon for car headlights, and krypton in lasers.

Well done for your learning today.

There's a lot of information there, and I hope you're feeling a lot more confident about the properties, and the electronic structure, and some of the uses.

So, the key thing is to remember those trends.

Well done, and I'll see you next time.