Video: Atomic structure

﻿Hi, my name's Dr. Patel and welcome to the sixth lesson in this topic of atomic structure and periodic table. In today's lesson we're going to be learning all about the atomic structure. Before we get started, I'd like you to do a couple of things for me. Please make sure that you're working in a nice quiet space free of any distractions. So if that means that you need to close down any computer tabs, do so now. Good, right. So, let's get started. Can you write today's date and title at the top of your page and today's title is atomic structure. Pause the video now if you haven't already done this. So in today's lesson, you're going to need a few pieces of equipment. You're going to need a pen, a pencil, a calculator, and a copy of the periodic table. This is really important as we're going to be using it a lot in today's lesson. If you haven't already done so please go and download this from the downloadable resource section from this lesson. I mean today's lesson, we're going to be learning all about the structure of the atom. We're going to learn all about the different charges and masses of the subatomic particles, and I'm going to explain what that means. And hopefully by the end of this lesson, you should be able to calculate the number of each subatomic particle. So what is the structure of the atom? So what exactly are subatomic particles? Well, sub-atomic can actually be divided into two parts. Have you ever heard of a word that has the prefix sub? What words have you heard of? Some of you will have said submarine. Submarine, the word sub just means under or inside. We've come across the meaning of the word atomic and it makes sense, it just means atom. So subatomic, literally means under or inside an atom. There are three main subatomic particles that are found inside an atom. The first is an electron, then, it's a proton, and the third is a neutron. So here is a diagram of an atom. The yellow circles represent electrons, and you can see that they carry a negative charge. The red circles are protons, and they carry a positive charge. So the way that I remember, protons is that you've always got to think positive like a, proton good. And the green circles represent neutrons. They actually don't have a charge so neutrons are neutral. The protons and neutrons are found in the nucleus of an atom. So this is different from a cell nucleus which you may have learned about in biology. So a nucleus contains protons, and neutrons, remember that. The electrons are found orbiting the nucleus. So if you imagine this almost looks like the solar system, where you've got the sun in the middle, and you've got the planets orbiting the sun, an atom is very, very similar. You've got the nucleus in the middle, and you've got the electrons orbiting the nucleus they're constantly moving around. So electrons are found on energy shells that orbit the nucleus. You also need to know that atoms are very, very small. They're one times 10 to the minus 10 metres, and that's a really, really small number. Pause the video now, and draw this diagram and make sure it's labelled. And then we're going to give you a quick quiz. So let's see how much you remember. Where are electrons found within an atom? Point to the screen or say your answer out loud. Good, well done if you remembered that they're on energy shells or energy levels. They're always sound orbiting the nucleus. Okay, true or false, electrons are found in the nucleus. Excellent if you said false, they are found orbiting the nucleus. They're not inside the nucleus. Where are protons found within an atom? Well done if you said nucleus. Protons are those positively charged particles that are found in the very centre of an atom, called a nucleus. Oh, this is a tricky one. What is the radius of an atom? Do you remember? Metres. Well done if you picked this option, you were really paying attention to just how small an atom is. So let's learn a little bit more about subatomic particles. When I introduced you to the structure of the atom, I mentioned the charges of protons, electrons, and neutrons. Can you remember what the charge of a proton is? Well done if you said positive. The charge of a proton is actually plus one. How about a neutron? Think about the word neutron. What does it sound like? Good, if you said zero or neutral. The charge of a neutron is neutral. And finally, what about the charge of an electron? Think about where it is on the diagram. Good, electrons are negative and they actually carry a minus one charge. Now obviously, in addition to carrying a charge, each particle will have a mass. If it didn't have a mass, it wouldn't exist. Each one of the subatomic particles has to have a mass. The mass is never zero. What's the mass never? Good, the mass is never, never zero. So the mass of a proton is one. The mass of a neutron is also one. And the mass of an electron is actually 1/2000 or 0.0005. In essence, the size of an electron is very, very, very small in comparison to a proton and a neutron. So which subatomic particles carry the highest mass in an atom? Good, a proton and a neutron is where most of the mass of an atom comes from. The electrons are very small and so they don't contribute much to the mass. Pause the video now and make a note of these charges and masses of each subatomic particle. I'm going to test you in a minute. So make sure that you've learned them. So let's see how much you remember. Where are neutrons found within an atom? Good, they're found in the nucleus of an atom. What's found on energy shells? Yeah, exactly, electrons. Which subatomic particles are responsible for most of the mass of an atom? So which subatomic particles have the highest mass and therefore contribute the most mass to an atom? Good, it's protons and neutrons. Do you remember the mass of each one of these? Exactly, it's one and one. So what is the charge of an electron? Good if you said negative, even better if you said minus one. You can actually get different types of negative numbers. So you can get, minus one, minus two, minus three, and minus four and so on. An electron is always minus one, so the best possible answer that you could write down is minus one. Okay, let's see if you remember this one. What's the charge of a proton? Good, think positive like a proton. Protons carry a charge of plus one. What about this one? What is the mass of a neutron? Be careful with this one, the question says the mass, not the charge. What's the mass of a neutron? Good, if you said one well done. If you said zero, then that's the charge of a neutron, not the mass of a neutron. People often get this muddled up. So mass, can anything ever have a mass of zero? Absolutely not. So nothing can have a mass of zero, it has to have a mass attached to it. How about this one? What is the charge of a neutron? So this time it is about the charge. What's the charge of a neutron? Good, the charge is zero or neutral. The clue is in the name. Okay, what is the charge of an electron? Let's see if I can trick you out. What is the charge of an electron? Good, it's minus one, well remembered. What's the mass of a proton? Remember its mass not charge. Good, it's one. The mass of a proton is one. Okay, so what's the mass of an electron? Do you remember the number? Well done if you said 1/2000 or 0.0005. You could also have said almost zero. But if you said zero, then that would be wrong. Why is that wrong? Good, because no subatomic particle can ever have a mass of zero. Okay, what is the charge of a proton? Good, think positive like a proton, so protons P for P plus one. What is the mass of a neutron? Be careful with this one. What is the mass of a neutron? Good, it's one. If you said zero, you got caught out and I managed to trick you. What is the charge of a neutron? Good, it's zero. So it is neutral. What is the mass of a proton? Well done, you're reading the question a lot better. So the question said mass, and therefore you needed to write one. It did not say charge so you don't right plus one. What's the mass of an electron? 1/2000 or almost zero. You could also have said 0.0005. If you said minus one you got tricked by the question and you need to read it more carefully. It said mass not charge. What's the charge of a neutron? Well done if you read the question properly and picked up on the charge, it is neutral or it has no charge. Okay, so hopefully you have a better understanding of the structure of an atom, and the key points about subatomic particles. Pause the video now and answer these questions using full sentences. Complete questions one to five and then we'll move on to the second part of this independent practise task. Pause the video now. Okay, so let's review the questions for one to five. Pause the video now and compare your answers to the ones on the screen. Hopefully, you've read the question properly for question five, and you wrote about the mass of a proton rather than its charge. Okay, here's the next set of independent practise questions. Remember, read the questions very, very carefully before stating your answers. Pause the video now and answer these using full sentences. So here's the answers to questions six to 10. Pause the video now and compare what you've got written down with the ones in front of you. Remember for a proton, and an electron, it's always better to say plus one or minus one. Also, for the mass of an electron if you write zero that would be incorrect, because no subatomic particle has a mass of zero. It wouldn't exist if it had a massive zero. Okay, so let's move on to the difference between atomic number and atomic mass. So every element on the periodic table we'll have two numbers attached to it, a large number and a smaller number. The smaller number, always represents the number of protons and this is known as the atomic number. So in this case, we've got sodium, we've got the symbol for sodium, and sodium has got it 11 protons because the smaller number represents the number of protons. The larger number is known as atomic mass. Now the atomic mass represents the number of protons and neutrons. Make sure that you learn this because you're going to get quizzed on it in a minute. So atomic mass is protons and neutrons, and atomic number is the number of protons on their own. Okay, so I'm going to show you a series of elements and you're going to have to tell me what the atomic mass or the atomic number is for that element. So remember, atomic number is the smaller number, atomic mass is the larger number. So the first one is oxygen, what's the atomic mass of oxygen? Well done if you said it's 16. Atomic mass is the larger number and therefore it's 16. How about magnesium? What's the atomic mass of magnesium? Good, it's 24. It's the larger number on the symbol. What's the atomic number of sulphur? So this time it's atomic number, not atomic mass. Good, it's 16. It's the smaller number, atomic number smaller number, atomic mass larger number. What's the atomic number of calcium? Good, it's 20. So atomic number is the smaller number. Atomic mass of lithium? Good, it's seven. Okay, you're getting the hang of this. How about this one? Atomic mass of carbon? So this time atomic mass. Good, it's 12. How about this one, sulphur? So atomic mass of sulphur? Good, it's 32. Okay, so what does the atomic mass represent? So now that you can recognise the atomic mass and the atomic number, do you remember what I said they represent? So atomic mass represents which subatomic particles? Well done if you remembered that it was protons plus neutrons. So the atomic mass is the larger number, and it tells you the number of protons plus neutrons. Okay, what does the atomic number represent then? Good, it represents the number of protons. What does atomic mass represent again? Good, it's the number of protons plus neutrons. How does that differ from atomic number? Good, atomic number is only the number of protons so there are no neutrons in atomic number. Okay, so how can I use these two numbers to calculate the number of each subatomic particle? So, as chemists we're interested in how many protons, neutrons, and electrons are found in each atom. So you need to be able to calculate the number of each subatomic particle. Okay, so here's how you can calculate the number of protons, neutrons, and electrons and we're going to use fluorine as a worked example. So firstly, we know that atomic number represents the number of protons. So the smaller number is atomic number, and therefore it represents the number of protons. So you can just read it off the symbol. The number of electrons in a neutral atom, so that is one that hasn't reacted it is just the atom on its own, is always the same as the number of protons. So it's easy, if you are looking for the number of electrons in an atom, a neutral atom, then it is always the same as number of protons. So if we look at fluorine, it's got how many protons? Think about the atomic number. Good, it's the smaller number, so it's got nine protons. So how many electrons would fluorine have? Good, it would also have nine. There are nine protons and nine electrons. And to calculate the number of neutrons, you've got to do atomic mass minus atomic number. So the larger number take away the smaller number. So try and do that in your head. Good, so 19 minus nine, and that gives you 10. So it's got nine protons, nine electrons, and 10 neutrons. Pause the video now and write down this worked example, resume playing the video once you've done this. Okay, have a go at this one. Can you work out the number of protons, electrons, and neutrons in lithium? So remember, atomic number is the smaller number. Which number is the atomic mass? Good, it's the larger one. So have a go. How many protons, neutrons, and electrons? So well done if you said that there were three protons, three electrons, and four neutrons. So the number of protons is the same as the atomic number, which is the smaller number. The number of electrons is the same as the number of protons. And the number of neutrons is the atomic mass minus the atomic number, so seven minus three. Have a go at this one. Calculate the number of protons, electrons, and neutrons in boron. Did you get these as your answers? So five protons, electrons of five, and there are six neutrons. Here's what you should have got. You should have got five protons, five electrons, and six neutrons. How did you do? Good. Right, let's look at argon. Hopefully you're getting the hang of this. So did you get, 18 protons, 18 electrons, and 22 neutrons? Brilliant. Okay, let's see if you can do bromine. You might need a calculator for this, although I'm sure you can do it in your head. Did you get 35 protons, 35 electrons, and 45 neutrons? Excellent if you did. Okay, let's look at carbon. Here's what you should have got, six protons, six electrons, and six neutrons. Okay, hopefully, you feel more confident with being able to identify what atomic mass and number represent, and calculating the numbers of each subatomic particle. Pause the video now and answer questions one to four of the independent practise, and then we'll go on to the next set of questions. Remember, pay special attention to whether it's asking about atomic mass, or atomic number. So here's what you should have got. Pause the video now and compare your answers with the ones on the screen. Remember, you needed to be really specific with your answers and make sure that your spellings are 100% correct. Okay, let's apply that knowledge to question four. So on the screen, there is the symbol for potassium. I want you to state each one of these five things for potassium. Pause the video now and see if you can answer this question. So here's what you should have got. Pause the video now and compare your answers with the ones on the screen. Hopefully, you got them all right. If you haven't, make sure you work out where you've gone wrong, so that you know not to make that mistake again. Okay, so let's apply that to an exam style question. So I'm just going to give you a minute to try and get your head around the question. If you need to pause the video just so that you can fully read the question, do that now, and then resume playing it once you've read the question so that I can give you some pointers. Okay, so the key things in this question that it's telling you, is that the atomic number of aluminium is 13, the atomic mass of aluminium is 27. And what it wants you to do is it wants you to describe, so describe is say what you see or describe numbers, and you need to describe the structure of aluminium. So we're thinking about an atom. So what is the structure of aluminium? And it gives you some tips, you need to talk about the number of each subatomic particle. So, which subatomic particles do you need to name in your answer? Good, protons, electrons, and neutrons, and you need to talk about the number of each of those subatomic particles. You need to mention the charge, and the mass, of each sub atomic particle. So remember, right at the beginning of the lesson we learned about charges and masses. So what's the charge and a mass of each subatomic particle. And finally, you need to know about the location within an atom. So where are these subatomic particles found? Think about where they're found within an atom. Again, we did this at the very start of today's lesson. Pause the video now and answer this question. You may want to divide your answer up into three parts. So three paragraphs to answer each one of these things separately. Okay, so here's the key things that you should have written down. The first bullet point asked you to talk about the number of each subatomic particle. So you should have said that there were 13 protons because that's what the atomic number told you. You should have said that there were 13 electrons because the number of protons equals the number of electrons. And you should have calculated the number of neutrons as 14 because you should have done 27 minus 13 and that gives you 14. For the second bullet point, you needed to have stated the charge and the mass of each subatomic particle. And so you needed to have mentioned each one of these for each subatomic particle. So for example a proton has a mass of one, and a charge of plus one, so writing it in a sentence. So here's what you should have written about the location of each subatomic particle. So protons and neutrons are always found in the nucleus, whereas electrons are on energy shells. You needed to have the key words that are in turquoise, in order to get the marks. Pause the video now and make any corrections that you need to. Okay, so that brings us to the end of today's lesson. Hopefully, you have a better understanding of the structure of an atom, and you know a little bit more about each subatomic particle inside an atom. Hopefully you also are able to calculate the numbers of protons, neutrons, and electrons, because we will be relying on you being able to do this in following lessons. Before you finish today's lesson, I'd like you to make sure that you complete the quiz. This will help test your understanding of today's lesson, but also celebrate all the hard work that you've done today.

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Completed: Atomic structure

In this lesson, we will describe the structure of an atom, understand the difference between atomic mass and atomic number. Calculate the number of protons, neutrons, and electrons within an atom.

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Atomic structure

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