If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content
Current time:0:00Total duration:3:56
AP.Chem:
SAP‑1 (EU)
,
SAP‑1.A (LO)
,
SAP‑1.A.3 (EK)
NGSS.HS:
HS‑PS1‑1
,
HS‑PS1‑2
,
HS‑PS1.A.2

Video transcript

in many videos we have already talked about electron configuration and now in this video we're going to extend that understanding by thinking about the electron configuration of ions so these are going to be charged atoms so let's just start looking at some examples let's say we are dealing with fluorine now we know what a neutral fluorine atoms electron configuration would be in fact if you want a little bit of practice try to pause this video and think about what is the electron configuration of a neutral fluorine atom all right now let's work through this together a neutral fluorine atom has nine electrons and we could just use our periodic table of elements so first we're going to have two electrons in 1s so we'll have one s two and then we're going to go to the second shell so then we go to two s two so so far we have filled in four electrons and next we go to the 2p sub-shell and we are going to have if we're talking about a neutral fluorine we are going to have one two three four five electrons in that 2p subshell so it's 2p five so if that's the electron configuration for fluorine what do you think the electron configuration for fluoride would be so this is just the anion that has one extra electron it is a negatively charged ion pause this video and try to figure it out well here you're now going to have one extra electron the fluorine has nabbed an electron from someplace and so where will that extra electron go well our 2p sub-shell has space for one more electron so that's where it will go so the fluoride anion is going to have an electron configuration of 1 s 2 2 s 2 2 P and that's going to have an Electra electron here 2p 6 2p 6 now let's do another example let's say we wanted to figure out the electron configuration of a part positively charged calcium ion so calcium let's make it 2 plus so that's a positive charge of 2 so this is you could view this as a neutral calcium that has lost two electrons what would be its electron configuration pause this video and try to figure that out all right well one way to figure this out is first we could figure out the electron configuration of a neutral neutral calcium neut neutral calcium atom and then from that we can take two of the highest energy electrons away and so neutral calcium you could view it actually let's do it in noble gas configuration neutral calcium the noble gas that comes right before calcium is argon so it's going to have the electron configuration of argon and then we are going to have two electrons for that fourth shell that's going to fill in the four s subshell and so we're going to have argon and then we're going to have let me do this in a new color let's call this for s2 now what do you think is going to happen if we were to lose two electrons well those two electrons in that four s subshell and that fourth shell are going to go away and so the electron configuration here for calcium with a positive two charge this calcium cation is going to be the electron configuration of argon and no 4s to so it's actually going to have the exact same electron configuration as argon so I will leave you there just a couple of examples and I encourage you if you're feeling if you're in the mood just pick any of these atoms any of these elements and think about what would happen if they gained or lost an electron and what their electron configurations might be
AP® is a registered trademark of the College Board, which has not reviewed this resource.