Atoms- Smallest Unit of Matter Example 3

by Jason Amores Sumpter
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all right. So here we have an example problem that says, According to the octet role, electron distribution in each shell of a neutral nitrogen atom with an atomic number of seven is which one of these four 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 show. 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 seven. So let's go ahead and say that this green circle here represents the nucleus of our nitrogen Adam, which once again we know, has an atomic number of seven. So we know that it has seven 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 zero, which means that the positively charged protons are gonna be balanced out perfectly with the number of negatively charged electrons. So if there are seven positively charged protons. There must be seven negatively charged electrons in order to make this nitrogen atom neutral. So we have to draw a total of seven electrons. So considering that we could go ahead and draw our first energy shell and we know that the first energy shell holds a maximum of two electrons. So we could go ahead and fill this first energy shell here with two electrons, as we see here. And then the other electrons need to go into the next shell so we could go 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 seven electrons. We've already got two. So we gotta put five Maurin the second shell, so we could go ahead and put four and five electrons in this outer shell. So once again, there is a total of seven electrons here that balance out the seven protons, which makes this nitrogen atom neutral. And so now 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 two 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 two electrons, which once again is correct. We could see the first energy shell does have two 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's a total of five electrons, not for electrons, so we can go ahead and eliminate. Answer. Option B. Here we can eliminate answer option B and go ahead and indicate that his answers options. See here that is the correct answer for this example problem, and the reason for that is once again, the two 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 five indicates the number of electrons in the second energy shell. And once again, there are five when you count those up and so see, here is the correct answer to this example, and I'll see you guys in our next practice video.