This is going to be a really short vodcast on how to write noble gas electron configurations. Basically it's a shortcut on how to get by some of those really long electron configurations. So at this point you should be familiar with how to write electron configurations. So some examples just because of refresher, phosphorus, 1s2, 2s2, 2p6, 3s2, 3p3, and you got bromine which is quite long itself.
And it can go even longer if you have to go all the way down to the row 6 or row 7. So we're going to show you a shortcut, which you don't have to go so long. Okay, the way we do it is, so for phosphorus, what we do is, phosphorus is located right here on the periodic table. We will look for the most previous noble gas, in which case this is neon. We will write it in brackets, so neon in brackets.
and then you just begin your scientific, I'm sorry, your electron configuration from there, 3s2 to 3p6. We assume if you have to count electrons, you just add up the number of electrons that neon already has, which is already 10, and it'll be consistent when you you have to add the electrons up for the electron configuration. Bromine, which was quite long, you can also shorten that. So the most recent one for bromine was argon.
So we begin with argon in brackets, and then we do 4s2, 3d10, and then 4p5, and that's it. It makes it quite simple. Okay, so let's try some on your own.
Go ahead and click pause, try these out, and let's see how you do. Okay, for magnesium, the noble gas before magnesium is neon. So I'm going to get neon, put it in brackets, and then it's just going to be a 3S2.
That was pretty easy. For iron, the most recent element before Fe is going to be argon. So you just put argon in brackets.
And then you begin from the notation there, which is going to be a 4s2. And then we've got to check for iron, which is going to be a 3d6. And barium, which can be a headache if you ever had to do the long way with barium. The most previous noble gas before barium is going to be zeon.
So you put zeon in brackets. And then you just begin from there, and this is going to be a 6s2. That's such a headache solver. All right, there you go.