Lesson video

Welcome to today's lesson on atomic structure.

We are going to be referring to the math of the electron throughout this lesson as negligible.

It's part of the unit atomic structure in the periodic table.

My name's Mrs. Mytum-Smithson, and I'm so pleased that you've come along to learn with me today.

I think that this is sometimes a tricky topic for students, however, we're going to work through it step-by-step, so you have nothing to worry about.

By the end of the lesson, you should be able to describe the physical characteristics of atoms, protons, neutrons, and electrons.

Here are the key words for today's lesson, electron, proton, neutron, nucleus, subatomic.

On the next slide, there's some sentences that include these key words.

If you wish to pause that slide and have a read, feel free to do so.

This lesson consists of two learning cycles.

The first is subatomic particles, and the second is physical characteristics of an atom.

Don't worry at this stage if you're finding these words a little bit daunting.

By at the end of this lesson, you'll be very familiar with them, and you're gonna be an expert.

So let's get on with our first learning cycle, subatomic particles.

An atom is the smallest unit of matter, and everything's made up of atoms. So if you took something and you zoomed in on it enough, you would eventually come across an atom.

And an atom is made up of three subatomic particles, protons, electrons, and neutrons.

Each element has got a different number of subatomic particles that's unique to it.

What does that word subatomic mean? Well, sub is from the Latin meaning below or smaller than, and atomic means from an atom.

So today we're going to be looking at the three subatomic particles, so the three particles that are smaller than an atom, these are protons, electrons, and neutrons.

What I'd like you to do now is name the three subatomic particles.

Is it A, atom, proton, electron, B, atom, nucleus, element, C, neutron, proton, electron, D, element, electron, atom? Pause the video for some thinking time.

Press play when you've got your answer.

So well done if you said that the three subatomic particles were C, that is a neutron, a proton, and electron.

Those are the three particles that are smaller than an atom.

That is what an atom is made up of.

Here's our image of an atom, it's not drawn to scale, and we're going to go on to talk a little bit more about that later on in the lesson.

And we're going to take a look at the centre of this.

Now, the centre of this is called a nucleus.

And in the nucleus, you're going to find two of those subatomic particles.

You're going to find the neutrons and the protons.

And around that, so orbiting, which just means going around.

So orbiting the nucleus in the shells are electrons, and the electrons move around the nucleus, and the nucleus consists of neutrons and protons.

So, where would you find the protons? Here, here, or here? Pause the video for some thinking time.

Press play when you've got your answer.

Well done if you said that you would find the protons in the centre of the atom.

That's called the nucleus.

Well done if you got that one right.

The other two that were circled were the electrons, and they're in shells orbiting around the nucleus.

The subatomic particles have got different charges, and all this means is that a proton is positive.

So usually the way I remember this is proton begins with a P, and positive also begins with a P, so protons are positive.

And then the electrons, they are negative.

So the electrons are negative, <v ->1 charge on an electron.

</v> And finally, the neutrons are neutral.

Sometimes this is written as zero, sometimes it's written as neutral.

So neutrons are neutral.

That starts with the same letter, so that's a good way to remember that.

Neutrons are neutral.

What is the charge on an electron? Is it A, -1, B, zero, C, +1? Pause the video now for some thinking time.

Press play when you've got your answer.

Well done if you said it's A, it's -1, an electron has a negative charge.

We've looked at the electric chargers on an atom, and now we're going to look at the masses of the subatomic particles.

So protons have got a relative mass of one, and electrons have got a significantly smaller mass, and they got a mass of roughly 1/1835.

And we can say that this is negligible.

Now you can see that I'm finding it difficult to say negligible.

It just means that it's very, very small, and it's so small that we don't count it.

So if I took 1,835 electrons, they would have the same mass as a proton.

So you can see, it is very, very small.

It is negligible.

And finally, we've got the neutrons.

Neutrons have got a relative mass of one, so the mass is in the centre of the atom.

We've got protons, which have got a mass of one, neutrons, which you've got a relative mass of one, and electrons, their relative mass is negligible, or 1/1835.

What is the mass of an electron? Is it A, -1, B, -1/1835, C, one, or D, negligible 1/1835? Pause the video for some thinking time.

Press play when you've got your answer.

Well done if you said D, it's negligible, that means sometimes it's so small, so it's 1/1835.

It's so small that we don't count it at all.

Now we're going to summarise our knowledge in this task.

So I'd like you to complete the following table.

So you've got a column for the subatomic particles.

One subatomic particle has been completed for you.

Got the electron in there.

Location.

So, where are you going to find these subatomic particles? We've got one location written there, which is the nucleus.

And then we've got charge.

So what charge are they? We've got one there, which is written +1, so positive one.

And then you've got two other possible charges, and you need to write those in there.

And finally, the mass.

So how much mass do the subatomic particles have? Pause the video now and complete the task, then press play, and we'll go through the answers.

Well done for working really hard and completing that task.

So we're going to have a look at the subatomic particles.

We've got protons, electrons, and neutrons, so well done if you've got those right.

And where are we going to find them? So the protons are located in the nucleus along with the neutrons, which are also in the nucleus, and the electrons are orbiting the nucleus in shells, so they're moving around the nucleus in shells.

Well done if you've got that one.

And then we've got the charge.

So the protons, remember I said protons are positive, P and P, protons are positive.

And then we've got electrons, and they're negative.

And finally, we've got neutrons, which are neutral.

So if you'd have written zero or no charge, that's absolutely fine.

If you'd written neutral, I'll also give you that as an answer.

So then we've got the mass.

So the mass of a proton is one, the mass of an electron, remember, they're significantly smaller, significantly lighter.

They are 1/1835, or that word that we learned today, negligible.

Difficult to say, but it just means that it means that the mass is practically zero.

So then we've got the neutron written in there as well.

So the two subatomic particles that have got significant mass are the protons and the neutrons, and they're in the nucleus.

So all of the mass is in the nucleus.

Well done, if you completed that task.

You've done really well.

Here's part two of task A.

What I'd like you to do now is correct the errors in the diagram that Izzy has drawn.

So she's drawn a diagram of an atom, and she's labelled it up and drawn it incorrectly.

I want you to correct the errors in this diagram that Izzy's drawn.

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

Well done for working really hard and completing that task.

Let's see how you got on.

So here were the errors.

So the shell and the nucleus labels were swapped.

So the nucleus should be the part in the middle that contains the neutrons and the protons.

And the outside is the shell, so that's the circle, that's the shell, and that should contain the electrons.

She had swapped the proton and neutron labels over.

So the protons should be labelling up the positive, and the neutron is labelled up with neutral subatomic particles.

Then we've got the electrons, and they're labelled with a negative sign, not a positive sign, as she had done.

So your electron should be negative in the shells, neutron should be neutral, proton should be positive, and the neutrons and the protons should both be in the nucleus.

So well done if you got that correct.

You've worked really hard, and you're very knowledgeable now about subatomic particles.

Well done for working really hard during the first learning cycle that was called subatomic particles.

Now we're moving on to physical characteristics of an atom.

Now we're going to have a look at the physical characteristics of atoms. So an atom has no overall electric charge, and this is because it contains equal numbers of protons and electrons to balance out the charges.

So let's have a look at an example of this.

So we've got a lithium atom.

A lithium atom has got three electrons, three protons, and four neutrons.

So here's our three electrons, and the charge, you can see, is cancelled out by those three protons.

And then we've got some neutrons in there.

So the three negative electrons cancel out the charge of the three positive protons, but the neutrons have got no charge.

So it doesn't matter if you've got three or four because the neutrons have got no charge, so they don't affect the overall charge of an atom.

But you will always have, on an atom, the same number of electrons and protons in an atom, and that's what makes it neutral.

So here's another example.

So this is boron this time.

Now sometimes the atoms have the same number of electrons, protons, and neutrons, but not always.

So this example has got five electrons, five protons, and six neutrons.

So if we have a look here, here's our five electrons.

So we've got five negative charges, and they're cancelled out by those five positive charges.

Then, if we have a look, we've got six neutrons.

So the five negative electrons cancel out the charge of the five positive protons, but as the neutrons don't have a charge, they do not affect the overall charge of an atom.

Let's have a quick check for understanding.

An aluminium atom has 13 electrons, 13 protons, and 14 neutrons.

What is the overall charge of an aluminium atom? Is it -1, is it zero, is it +1, or is it +26? Pause the video for some thinking time.

Press play when you've got your answer.

Well done if you said zero.

Those 13 electrons are negative and the 13 protons are positive, so they cancel each other out, and it doesn't matter about the number of neutrons because they're neutral, they don't affect the overall charge.

Well done if you got that one correct.

Atoms are very small, they're about one times 10 to the -10 metres, or 0.

1 nanometers in size, and the nucleus is very small compared to the overall size of an atom.

The nucleus is about 10,000 times smaller than the atom.

So just to give you an idea of scale, if we took an atom and we scaled it up so that the atom was the size of a football stadium, just like the one that's pictured here, the nucleus would only be the size of a marble or a small grape.

So you can see there's a big difference in the size of the atom and the size of the nucleus.

Here's a quick check for understanding now.

Complete the sentence.

The nucleus of an atom is small compared to the overall size of the atom, is very small compared to the overall size of the atom, or is very large compared to the overall size of the atom.

Pause the video now for some thinking time.

Press play when you've got your answer.

Well done if you said it is very small compared to the overall size of the atom.

The nucleus of an atom is about 10,000 times smaller than the atom.

Well done for working really hard so far this lesson.

Now we're going to look at this table of information.

I'd like you to complete the table of information.

You can see it's got some missing information.

It's a list of elements.

So we've got a list of elements, and it's telling you how many electrons there are in that element, how many protons there are, and how many neutrons there are.

So we've got the three subatomic particles there, and we're going to look at the impact on the overall charge of the atom.

So what I want you to do is complete the table of information, pause the video now, complete that task, and press play when you've got your answers.

Well done for working really hard on that one.

So all you've got to do now is some simple maths.

So when we look at beryllium, if I've got four electrons, that means I've got four negatives.

I've got four positives because I've got four protons.

And I've got five neutrons, which don't impact the overall charge of an atom.

So the four electrons cancel out the four protons, giving me an overall charge on the atom of zero.

Then we're going to have a look at nitrogen.

We've got seven electrons, seven protons, seven neutrons, and all that means is that we've got seven negatives and seven positives, and they cancel each other out.

Remember, the neutrons don't have any impact on the overall charge of the atom, so that is indeed zero.

Then, if we have a look at sodium, again, we've got 11 electrons, they're negative, and we've got 11 positives, and the neutron's 12.

It doesn't matter how many of those we've got because they don't impact on the overall charge of the atom, so that is again zero.

Now this time round, we've got an overall charge of the atom of zero, and we're gonna have a look there.

We've got 20 neutrons.

Now, that doesn't impact the charge at all.

If we've got an overall charge of zero and we've got 20 electrons, that's a negative, so we've got 20 negatives, we must have 20 positives.

Well done if you've got that one.

Slightly difficult.

And again, similar thing here with the oxygen, if we've got eight positives, we must have eight negatives, so we must have eight electrons 'cause the overall charge on that atom is zero.

Again, it doesn't matter how many neutrons we've got because they're neutral and they don't affect the overall charge.

So finally, if we've got nine electrons, we must have an overall charge of zero on that atom, and we must have done that by having nine protons.

So well done if you managed to get all of that information correct.

There is no overall charge on an atom because the electrons always cancel out the protons in atoms. Well done for working really hard on that.

Well done for working really hard throughout this lesson.

Now we're gonna have a look at part two of task B.

What I want you to do for this task is complete the sentences using the information in brackets.

So A, atoms are very small or very big.

B, you've got two sizes to choose from here.

They have a radius of approximately 1 times 10 to the -14 metres, or 0.

00001 nanometers, or 1 times 10 to the -10 metres, or 0.

1 nanometers.

What I want you to do is choose either the numbers before the slash or after the slash.

And finally, C, the nucleus of an atom is significantly smaller or a similar size.

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

Well done for working hard and completing part two of task B.

Let's go through the answers now.

Atoms are very small.

They have a radius of approximately 1 times 10 to the -10 metres, or 0.

1 nanometers.

The nucleus of an atom is significantly smaller.

So you can see from this, the atom's very small, and they've got a very small radius, but the nucleus is even smaller, is significantly smaller than the atom.

Well done if you worked really hard and got those correct.

Well done for working really hard this lesson.

We're now gonna do part three of task B.

Imagine you were asked to make a model of an atom.

Explain why you could not make it to scale.

You can use a labelled diagram and the following prompts to help you.

So here's some prompts.

Atom, nucleus, significantly larger or smaller.

So you can use all of those words or some of those words to help explain why you couldn't make a scale model.

Pause the video, complete the task, and press play when you've got your answer.

Now the atom is significantly larger than the nucleus, and you might have written that the nucleus is significantly smaller than the atom.

Therefore, it's going to be too difficult to make a model to show the nucleus and the atom to scale.

You would need such a large piece of paper or be able to draw such a small dot to represent the nucleus that it would be impossible to do a scale model of the nucleus and the atom together.

Well done if you got that correct.

Here's a summary of everything you should have learn today.

Electrons have a relative charge of -1 that attracts them to the atomic nucleus, and roughly a relative mass of 1/1835 negligible.

Protons are found in the atomic nucleus, have a relative electric charge of +1, and a relative mass of one.

Neutrons are found in the atomic nucleus, have no charge, and a relative mass of one.

An atom has no electric charge as it contains equal numbers of protons and electrons to balance the charge.

The atom has a nucleus surrounded by electrons with a nuclear radius much smaller than that of the atom.

Well done for working really hard throughout this lesson.

I think there was some tricky concepts in there.

However, I'm sure that you've done really well and are now an expert on atoms. You should have learned about the subatomic particles, and their masses, and their chargers, and where you would find them.

Well done for working really hard this lesson.