Alright. So here we have an example problem that says according to the octet rule, electron distribution in each shell of a neutral nitrogen atom with an atomic number of 7 is which one of these 4 potential answer options down below? Where the first number of each answer option suggests the total number of electrons in the first energy shell, and the second number of each answer option represents the total number of electrons in the second energy shell. And so really what we need to do is draw ourselves a little sketch of a neutral nitrogen atom, which once again has an atomic number 7. So let's go ahead and say that this green circle here represents the nucleus of our nitrogen atom, which once again we know has an atomic number of 7, so we know that it has 7 positively charged protons in its nucleus.

But then it tells us that the nitrogen atom is neutral, which means that it's going to have an overall net charge of 0, which means that the positively charged protons are going to be balanced out perfectly with the number of negatively charged electrons. So if there are 7 positively charged protons there must be 7 negatively charged electrons in order to make this nitrogen atom neutral. So we have to draw a total of 7 electrons. Considering that we can go ahead and draw our first energy shell, and we know that the first energy shell holds a maximum of 2 electrons. So we can go ahead and fill this first energy shell here with 2 electrons as we see here, and then the other electrons need to go into the next shell.

So, we can go ahead and draw our second energy shell and of course, we can put the remaining electrons here. So we know that there must be a total of 7 electrons. We've already got 2, so we got to put 5 more in the second shell. So we can go ahead and put 1, 2, 3, 4, and 5 electrons in this outer shell. So once again, there's a total of 7 electrons here that balance out the 7 protons, which makes this nitrogen atom neutral.

And so now all we need to do is take a look at the answer options and once again we can see that the first energy shell here has a total of 2 electrons not one electron as option a and option d indicate. So we can go ahead and eliminate answer option a and answer option d just based on that. However, when we look at answer option b and answer option c notice that they both suggest the first energy shell has 2 electrons, which once again is correct. We can see the first energy shell does have 2 electrons. So then we need to look at the second number which is really how these two answers differ and you can see that the second energy shell when you count them up there is a total of 5 electrons not 4 electrons.

So we can go ahead and eliminate answer option b here. We can eliminate answer option b and go ahead and indicate that answer option c here, that is the correct answer for this example problem. And the reason for that is once again, the 2 here indicates the number of electrons in the first energy shell, which you can see there's one here and the other is right here. And then the second number of 5 indicates the number of electrons in the second energy shell. And, once again there are 5 when you count those up.

So c here is the correct answer to this example, and I'll see you guys in our next practice video.